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MIDWEST FRIENDS OF THE PLEISTOCE~~:,)'-' 40th Annual Meeting r\--_F--~

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May 21.23, 1993

PLEISTOCENE GEOMORPHOLOGY AN5')rRATI~HY OF THE DOOR PENINSULA, ~SCONSI~

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Alían F. Schneider, Ed' or

í Sponsored by College of ~cience and Technology

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University of WJconsin-Parkside I ,

Kenosha, \\IÍsconsin 53141 f

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MIDWEST FRIENDS OF THE PLEISTOCENE

40th Annual Meeting

May 21-23, 1993

PLEISTOCENE GEOMORPHOLOGY AND STRATIGRAPHY

OF THE DOORPENINSULA, WISCONSIN

Allan F. Schneider, Editor

Sponsored by College of Science and Technology

University of Wisconsin-Parkside

Kenosha, Wisconsin 53141

CONTENTS

Route map for Day 1 ............................. '. . . . . . . .. Inside front cover

Meetings of tbe Midwest Friends of tbe Pleistocene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Sorne quotes of note from sorne old Friends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. vii

Preface ............-............................................ ix . M. E. Ostrom

Acknowledgments ......................... : . . . . . . . . . . . . . . . . . . . . . . . ., x

Introduction ...................................................... 1-

Geomorphology of Door County, Wisconsin .................................. 3 Allan F. Schneider

When Green Bay was a valley: The AuTrain-Whitefish-Green Bay Spillway ............. , 19 John D. Hughes

Glacial isostasy of tbe Door Peninsula, Wisconsin . . . . . . . . . . . . . . . . . . . . ......... , 31 James A. Clark and Todd A. Ehlers

Till stratigraphy and late glacial sequence of tbe northern Door PeninslÚa, Wisconsin . . . . . . .. 37 Allan F. Schneider

Glaciation and karst features of tbe Dour Peninsula, Wisconsin ..................... , 47 Ronald D. Stieglitz and William E. Schuster

Europe Lake sediment cores and vegetation history .. . . . . . . . . . . . . . . . . . . . ....... , 53 William N. Mode and Louis J. Maher, Jr.

Molluscan faunal changes in Europe Lake, Wisconsin during tbe past 6,600 years ......... , 57 Barry B. Miller

The ostracode record from Europe Lake, Wisconsin: The past 6,600 years .............. 63 Alison Smitb and Beiwen Dai

Newport Village: A wilderness experiment .................................. 67 Coggin Heeringa

Beach ridges and lake-level history at Two Rivers, Wisconsin ...................... 71 Eric Dott

Hydrogeologyand water quality in tbe fractured dolomite aquifer, Door County, Wisconsin ... , 81 Kennetb Bradbury and Maureen Muldoon

iii

The Two Creeks Buried Forest (reprinted from WGNHS Information Circular 13) ........... 89 Robert F. Black

Radiocarbon confirmation of tbe Greatlakean age of tbe type Two Rivers till of eastern Wisconsin (reprinted from GSA Special Paper 251) . . . . . . . . . . . . . . . . . . . . . . . . . . .. 101

Allan F. Schneider

Environmental analysis of a Twocreekan-aged beetle (Coleoptera) assemblage from Kewaunee, Wisconsin (reprinted from GSA Special Paper 251) . . . . . . . . . . . . . . . . . . . . . . . . . . .. 107

Clarke E. Garry, Robert W. Baker, Donald P. Schwert, and Allan F. Schneider

Road log, Day 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 117 Allan F. Schneider

Road log, Day 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. 139 Allan F. Schneider

Route map for Day 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inside rear cover

iv

I

MEETINGS OF THE MIDWEST FRIENDS OF THE PLEISTOCENE

1 1950 Bastern Wisconsin Sheldon Judson 2 1951 Southeastern Minnesota H.B. Wright, Jr. and R.V. Ruhe 3 1952 Western Illinois and Bastern Iowa P.R. Shaffer and W.H. Scholtes

(4) 1953 Northeastern Wisconsin F.T. Thwaites (5) 1954 Central Minnesota H.B. Wright, Jr. and A.F. Schneider 6 1955 Southwestern Iowa R.V. Ruhe

(7) 1956 Northwestern Lower Michigan J.H. Zumberge and W.N. Melhorn 8 1957 South-central Indiana W.D. Thornbury and W.J. Wayne 9 1958 Bastern North Dakota W.M. Laird and others

10 1959 Western Wisconsin R.F. Black 11 1960 Bastern South Dakota A.G. Agnew and others 12 1961 Bastern Alberta C.P. Gravenor and others 13 1962 Eastern Ohio R.P. Goldthwait 14 1963 Western Illinois J.C. Frye and H.B. Willman 15 1964 Eastern Minnesota H.E. Wright, Jr. and E.J. Cushing

. 16 1965 Northeastern Iowa R.V. Ruhe and others 17 1966 Bastern Nebraska E.C. Reed and others 18 1967 South-central North Dakota Lee Clayton and T.F. Freers 19 1969 Cyprus HiIIs, Sask. and Alba. W.O. Kupsch 20 1971 Kansas-Missouri Border C.K. Bayne and others 21 1972 East-central Illinois W.H. Johnson and others 22 1973 West-central MI & East-central WI E.B. Evenson and others 23 1975 Western Missouri W.H. Allen and others 24 1976 Meade County, Kansas C.K. Bayne and others 25 1978 Southwestern Indiana R.V. Ruhe and C.G. Olson 26 1979 Central Illinois L.R. Follmer and others 27 1980 Yarmouth, Iowa G .R. Hallberg and others 28 1981 Northeastern Lower Michigan W.A. Burgis and D.F. Eschman 29 1982 Driftless Area, Wisconsin J.C. Knox and others 30 1983 Wabash V alley, Indiana N.K. Bleuer and others 31 1984 West-central Wisconsin R.W. Baker 32 1985 Notth-central Illinois R. C. Berg and others 33 1986 Northeastern Kansas W.C. Johnson and others 34 1987 North-central Ohio S.M. Totten and J.P. Szabo 35 1988 Southwestern Michigan G.J. Larson and G.W. Monaghan 36 1989 Northeastern South Dakota J.P. Gilbertson 37 1990 Southwestern Iowa E.A. Bettis III and others 38 1991 Mississippi Valley, MO and IL E.R. Hajic and others 39 1992 Northeastern Minnesota J.D. Lehr and H.C. Hobbs 40 1993 Door Peninsula, Wisconsin A.F. Schneider and others

Editor's Notes: (a) No meetings were held in 1968, 1970, 1974, and 1977. (b) Meeting numbers in parentheses have been listed previously as "U" or unnumbered. (e) The 1952 meeting that is cornmonIy included in the Iist of Midwest FOP meetings

as southwestern Ohio was actually an Bastern FOP meeting in central Ohio -- to which Midwest Friends were invited· by Dick Goldthwait the previous week in western Illinois.

v

SOME QUOTES OF NOTE FROM SOME OLD FRIENDS (Witb sorne notes on tbe quotes from anotber Friend)

"The Midwestern Section of tbe Friends of tbe Pleistocene is an outgrowth of tbe Friends of tbe Pleistocene organized by a group of glacial geologists in tbe New England area before America's entry into World War n. Most active member of tbe original group has been Richard Foster Flint, Yale University.

In tbe Spring of 1950 a glacial trip in Wisconsin was hastily organized and attended by representatives from tbe University ofWisconsin, Beloit College, Lawrence College, lowa State College, University of Minnesota and University of Chicago. The group was referred to by sorne as tbe "Chowder and Marching Society of tbe Upper Midwest." The following year anotber meeting was held in Minnesota and tbe group tbere became known as "The Friends of tbe Pleistocene - Midwest Section," a name which has become established by continued usgae. " ,

F. T. Thwaites, 1953 (in Introduction to Field Guide, 1953 Midwest FOP)

Editor's Note: Altbough Mr. Thwaites stated tbat tbe name "The Friends of tbe Pleistocene -Midwest Section" had become established by continued usage, tbe title page of his fíeld guide refers to tbe organization as tbe "Friends of tbe Pleistocene (Upper Midwest Division)."

"In 1950, Al Schneider, Herb Wright, and Don Eschman got tbe Midwest Group going."

R. P. Goldtbwait, 1991 (in Friends of tbe Pleistocene: Recollections of Fifty Annual Reunions)

Editor's Note: Thanks for tbe credit Dick, you wonderful gentleman, but you are mistaken. Neitber Don nor I were involved in tbe founding of tbe Midwest group; Herb Wright was, along witb Shel Judson. In tbe spring of 1950, Don was at Harvard, eitber finishing his M.A. or beginning his Ph.D. under Kirk Bryan, and I was at Penn State, teaching historical geology and working on my M.S. under Frank Swartz. It was in 1950 tbat Don and I first met, when Marland Billings brought his structural geology c1ass from Boston to tbe folded Appalachians of central Pennsylvania. Two close friends of Don's and mine, John and Laura Miller, had moved to Penn State from Harvard a few montbs earlier, and Billings had asked John to arrange for tb(l group's overnight stay in State College. My first Friends meetings were two years later in tbe spring of 1952, when I attended botb tbe Midwest and Eastern Friends trips. Don's fírst Midwest Friends trip was probably in 1954, after he left Tufts and came to Michigan.

vii

On tbe use of tbe word "cell" (as in "Friends of tbe Pleistocene, Midwest Cell"):

"Pacific Group of FOP soon became tbe Pacific Cell and by 1980 tbe word "cell" spread to tbe Rocky Mountains. Thisautbor and sorne old-timers regret tbis spreading disease inasmuch as true Friends of tbe Pleistocene are neitber restricted by any rules or organizations (a cell is a small unit witb walls) nor are tbey afflicted witb any dictator or communist movement as tbat word has been used historically. "

R. P. Goldtbwait, 1991 (in Friends of tbe Pleistocene: Recollections of Fifiy Annual Reunions)

Editor's Note: Amen I You could not have said it better, Dick. (I suspect tbat I'm one of tbose old-timers, along witb Jane Forsytb, Bill Melhorn, Bob Ruhe, Bill Wayne, Sid White, and Herb Wright tbat Dick was referring to.)

•

"History records and interprets tbe events of tbe past. The significance of history becomes apparent when one recognizes tbat every "present" contains its own past. Had tbat past been different, tbe present would be unlike it is .... To tbe mind attuned, tbis endeavor to understand our present from tbe record of tbe past, is an intellectual adventure of absorbing interest. " "

J Harlen Bretz, 1939 (in Illinois Geological Su(Vey Bulletin 65, Part 1)

"Inasmuch as earth history is always an interpretation, and interpretors differ in tbeir evaluations of so-called facts, no one interpretation may necessarily be right. Furthermore, new data are constantly forcing us to revise our story .... Different points of view or interpretation of past history based on what is now availabl.e to us of tbose ancient events is not to be deplored."

R. F. Black, 1974 (in National Park Service Scientific Monograph Series, No. 2)

Editor's Note: Well stated, Bob. It almost seems as tbough Bob had Ed Evensons's 1973 Midwest FOP trip in mind, or perhaps he was anticipating Jim Knox's 1982 Midwest FOP trip.

"Afier all, over half of tbe" people in tbe United States and all tbose of Canada live on, and more and more in, Pleistoc~ne (mainly Wisconsinan) deposits tbat constitute a major par! of tbeir environment. These deposits are a key factor in tbat now magic term "environmental geology."

viii

George White, 1973 (in GSA Memoir 136)

PREFACE

Door County is recognized internationally for its beautiful natural setting and tbe many opportunities it offers for residents and visitors to enjoyo It is not surprising tbat as tbe county's reputation for beauty and opportunity has spread, more people havebeen attracted to tbe area and tbe amount of interaction between people and tbe natural resource base has increased. It is also not surprising tbat tbe added stress caused by increased interaction is having an increasingly serious effect on Iimited resources. Historically, people have tended to use tbe environment and natural resources to satisfy tbeir irnmediate needs witb tittle regard for tbe possible consequences. Therein is tbe dilernma tbat is becoming all too familiar to people responsible for understanding and managing natural systems to assure tbeir continued availability. Namely, how can we prevent serious damage to tbe beauty we cherish and tbe resources we rely on and at tbe same time use tbem to satisfy our spiritual and material needs?

ix

M. E. (Buzz) Ostrom, 1990 State Geologist of Wisconsin, retired

ACKNOWLEDGMENTS

1 arn indebted to many people who have contributed directly to the trip or have otherwise assisted in this endeavor o The following persons have all contributed to the guidebook or have assisted at the meeting in one way or another: Jim Clark (Calvin College, Michigan), Eric Dott (Delta Environmental Consultants, Sto Paul), Clarke Garry (UW-River Falls), John Hughes (Northern Michigan University), Ardith Hansel (IlIinois State Geological Survey), Coggin Heeringa (Newport State Park Naturalist), Jim Knox (UW-Madison), Lou Maher (UW-Madison), Barry MilIer (Kent State University), BilI Mode (UW-Oshkosh), Bill Schuster (Door County Conservationist), Ron Stieglitz (UW-Green Bay), and Alison Smith (Kent State University)o 1 also wish to thank the UW-Parkside students who have assisted with the logistics of the trip, as well as the support staff in the School of Science and Technology and the media services people at UW -Parksideo

Allan F o Schneider

x

INTRODUCTION

Welcome to Wisconsin's Door Peninsula, one of tbe most popular vacation and touris(areas in tbe upper Midwest.

The Friends of tbe Pleistocene are meeting in eastern Wisconsin for the first time in 20 years, tbe last time being in 1973 on the second day of Ed Evenson's trip on late Pleistoeene shorelines and red-till stratigraphy -- topies tbat will again be tbe foci of our attention tbis year. We will also once again examine tbe stratigraphy of the Two Creeks site, which tbe Friends have not visited for exactly 40 years (to tbe day!) -- the last time being in 1953 on Freddie Thwaites' trip in east-central Wiseonsin. Neitber of tbese excursions went farther north tban tbe very base of tbe Door Peninsula, however. This year we shall traverse nearly the entire length of tbe peninsula, from Europe Bay on tbe north to Point Beach on tbe soutb.

My own association witb tbe Door.goes back to tbe days of my childhood in tbe late 1920s and early 1930s. My roots, however, go back several generations, to my maternal great-grandparents, Peter and Anna Johnson, who settled in Door County upon emigrating from Denmark at about the time of tbe Civil War. My mother was raised in Ephraim, attended grade school at tbe historie Pioneer Sehoolhouse, and was confirmed at tbe Ephraim Moravian Church. 1 remember Ephraim before the big hotels had electricity, running water, and flush toilets, and when only unpasteurized milk was served at mealtime. Times have changed! Most of tbe old hotels have disappeared: Condominiums and motels are everywhere, and Door County has lost most of its earlier country charm.

As indicated in tbe announcements, our meetiQg tbis year will depart a bit from the usual strong emphasis on till stratigraphy. This aspect ofPleistocene geology certainly will not be ignored, however; several stops will be made to examine tbe principal till units of tbe area. But tbe geomorphology and scenery of the Door Peninsula will be aceorded major consideration.

On Saturday our route (inside front cover) will take us to tbe north end of the peninsula to observe modern and abandoned shorelines, bedroek control of geomorphic features and glacial history, tbin till deposits of late Woodfordian age, a small drurnlin field, and tbe postglacial geology and ecology of an inland lake. On Sunday (inside rear cover) we will examine a karst system west of Sturgeon Bay and then travel soutb to study an exposure of red clayey till, tbe stratigraphy of tbe Two Creeks site, and end tbe trip witb a discussion of beach ridges at Point Beach State Forest. Included in the road log are short deseriptions relating to tbe history and culture of sorne of tbe eornmunities o{ tbe peninsula.

Two major problems relating to tbe Pleistocene history oftbe Door Peninsula will be addressed on this trip: (1) tbe identification and eorrelation of late-glacial and postglacial shorelines, and (2) tbe age and source of the red clayey till tbat covers most of soutbern Door County and adjacent areas to tbe soutb. The shoreline problem will be considered at severa! stops on Day 1 of the trip. The till problem will be discussed at Stop 10 on Day 2. (The term "till" is used in tbis guidebook as botb a genetic and a deseriptive term; in a few cases, sediment called "till" might better be designated by !he term "diamicton. ")

1

The landscape of the northern Door Peninsula is attributable in large measure to the presence of late-glacial and postglacial shorelines. A short tour of the area may not impress a visiting scientist with the importance of these shorelines as a significant controlling element of the landscape, but a more careful examination of the eountry will confirm that this is indeed the case.

The study of these abandoned shorelines is extremely enigmatic; in faet, it is downright maddening. Identification and correlation of these features is made difficult for many reasons (itemized elsewhere in this guidebook). Indeed, our knowledge of old shorelines and former lake levels in this area has not been greatIy advanced as a result of recent studies, and one often wonders if any real progress has been made since the publieation of J.W. Goldthwait's fine bulletin on the abandoned shorelines of eastern Wisconsin in 1907 and Leverett and Taylor's classie Professional Paper in 1915. If one positive item has resulted from these recent studies, it would be the recognition of remnants of higher and older shorelines (probably pre-AIgonquin) that were not noted by earlier workers, including Goldthwait, O. L. Kowalke, and Thwaites and Bertrand. This finding was initially reported by Sehneider about five years ago.

• AlIan F. Sehneider

2

GEOMORPHOWGY OF DOOR COUNTY, WISCONSIN

Allan F. Schneider Department of Geology

University of Wisconsin-Parleside Kenosha, WI 53141

BEDROCK PHYSIOGRAPHY

Door County, Wisconsin covers Ihe northern four-fifths of Ihe Door Peninsula of eastern Wisconsin (Fig. 1). The peninsula is a linear ice-scoured, karstic bedrock upland developed on Ihe gently eastward-inclined dipslope of Ihe Niagara Cuesta (Fig. 2). It is underlain largely by fairly resistant dolomite formations of lower and middle Silurian age (Fig. 3), which are bordered by subparallel belts of less resistant rock units Ihat He benealh Ihe Lake Michigan and .Green Bay basins. The Lake Michigan basin is underlain by weak Devonian and Mississippian shales, while Ihe Green Bay basin is floored by Ihe non-resistant Ordovician Maquoketa shale and by older Ordovician carbonate rocles belonging to Ihe Sinnipee Group (platteville, Decorah, and Galena Formations). These rocles a1so underlie Ihe soulhward continuation of Ihe Green Bay lowland, occupied by Ihe Fox River valley, Lake Winnebago, Horicon Marsh, and in soulheastern Wisconsin Ihe broad Rock River lowland.

• Eau Claire • Wausau

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Madlson 9

Figure 1. Map of Wiseonsin showíng loeations of the Door Península and Door County (pattemed area) between Lake Miehigan and Green Bay.

3

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GENERALIZED CROSS SECTION NORTHERN DOOR COUNTY, WISCONSIN

Vertical exagge-ratlon: tOX

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~ chert

lit '1 "tal foSSils (unditlerenliale)

~ dolomite

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Figure 2. Cross seclion of Ihe Door Peninsula showing slrnligraphy .nd slruelure of Ihe bedroek unils. (prom Stieglilz, 1989, lig. 2.)

PREGLACIAL DRAINAGE AND BEDROCK V ALLEYS

The southem margin of the Laurentide Ice Sheet in late Wisconsinan time was strongly lobate across the northem United States, inc1udingWisCDnsin (Fig. 4), as shown by the pattem of concentric end moraines festooned around and beyond the margins of structurally controlled lowlands. It has generally been assumed that these bedrock lowlands were present in preglacial time and probably controlled the flow of glacier ice repeatedly throughout the Pleistocene Epoch. Thus, it has been assumed that both the Lake Michigan and Green Bay lowlands were present in one forro or another in late preglacial time and were subsequently scoured to their present size and shape by repeated glacial advances.

The approximate axis of the Lake Michigan basin is believed to have been occupied by the Ancient Michigan River (Martin, 1916, p.285). However, the absence of any known connection to the preglacial Mississippi River or to the Teays-Mahomet system in northem Indiana or northeastem IIIinois would . seem to prec1ude the possibility of southward-flowing drainage through the basin. Northward-flowing drainage through the Straits of Mackinac is a1so unlikely, since this would have involved numerous barbed tributaries, based upon Martín's hypothetical preglacial drainage pattern (Fig. 5). Thus, the flow direction ofthe Aneient Michigan River, assuming that it existed, remains unsolved.

Eastern Wisconsin, inc1uding Door County, is marked by a series of subparallel bedrock valleys, sorne occupied by modern rivers, that cross the area from west to east. It is generally believed that these valleys are a1so preglacial in age, a1though several of them were undoubtedly deepened by overflow waters from glacial Lake Oshkosh in the Fox River lowland during the late Wisconsinan (Thwaites and Bertrand, 1957; Wielert, 1980). Martin (1916, p. 285) theorized that these valleys were cut in preglacial time by tributary streams to the Ancient Michigan River (Fig. 5). According to Martin, the bedrock gap at Sturgeon Bay may have been cut by the preglacial (or interglacial) Menominee River, which crossed the present Green Bay basin and the Door Peninsula to enter the Ancient Michigan River at about the latitude ofTwo Rivers. Ifthis was indeed the case, the Green Bay lowland probably was not in existence in preglacial time as many have assumed.

4

But frorn u.s. G~lorle11 S\I,")' 1:500,000,196'

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EXPLANA TION

nJ~}1 NIAGARAN SERIES - Do1omite, buff- gra)', medium- to coatse. grained, thin·bedded too masslvo

~ ALEXANDRlAN SERIES - Dolo­mito, gray, medium- to caarse. grained, thick·bedded to mas. sive. Cherty With gypsum near base

• MAQUOKETA SHALE - Shal. and sha1y dolomite

Figure 3. Bedrock map of Door County. (prom Sherrill, 1978, fig. 2.)

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Figure 4. Lobes of Ihe lale Wisconsinan gl.cier in Wisconsin. Hachured line shows maximum exlenl of ice between 25,000 .nd 10,000 yr B.P. Arrows· indicale ice-flow direclions. Dolled orea represenls Ihe Keltle Moraine. (prom Wisconsin GeologicaI and Natural Hislory Survey.)

Citing severallines of evidence, Dutch (1989) has recently asserted tbat "tbe absence of a buried valley network in tbe Green Bay lowland suggests tbat tbe lowland did not exist before tbe Pleistocene. " KluesseÍldorf and Mikulic (1989, p. 24-25) have likewise implied tbat tbe Green Bay basin was not c~eated until tbe Pleistocene, when "tbe sharp, high edge of tbe Niagara Escarpment caused tbe Green Bay glacial lobe to divide off of tbe main soutbward-moving Lake Michigan glacial lobe, forcing it to scour out a patb in tbe soft Maquoketa Shale, creating botb tbe Green Bay and Lake Winnebago basins." Thus, tbe cause and effect relationship of tbe Green Bay Lobe to tbe Green Bay lowland remains in doubt.

In addition to tbe bedrock gap at Sturgeon Bay, Door County is crossed by several otber bedrock valleys tbat traverse tbe península witb a general northwest-soutbeast orientation. The most conspicuous of tbese valleys is tbat at Porte des Morts Passage or Deatb's Door, which separates tbe northem tip of tbe península from tbe islands of tbe Grand Traverse archipelago to tbe north. Sherrill (1978, p. 4) has confirmed tbe presence of botb tbe Sturgeon Bay and Deatb's Door valleys and has identified two additional major valleys in northem Door County, one of which crosses tbe county between Ellison Bay and Rowleys Bay and tbe otber between Ephraim and Baileys Harbor. Filled bedrock valleys in tbe area soutb of Sturgeon Bay have been recognized by Dutch (1980).

6

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Figure 5. Sketcll maps showing hypotlletical preglacial drainage and present dminage in eastero Wisconsin. (From Martin, 1916, lig. 109.)

Several other smaller bedrock valleys or lowlands a1so appear to be present. One apparently crosses the county between Sister Bay and North Bay, another between Little Sister Bay and Moonlight Bay, another between Egg Harbor and Clark Lake, and possibly one between Little Sturgeon Bay and AIgoma. Although partially filled with glacial deposits andorganic sediments, most of the bedrock lowlands can be recognlzed in !he field, as well as on landsat pictures and on Sherrill's (1978) bedrock

. topography map of Door County. .

Numerous measurements (total of 153) of joint sets in the bedrock (Fig. 6) by Sherrill (1978) and Dutch (1980) show a close correspondence between valley orientation and bedrockjointing and led Dutch to conclude that the preglacial drainage south of Sturgeon Bay was structurally controlled. Certainly this conclusion is equally valid for the bedrock lowlands no$ of Sturgeon Bay, where one set of bedrock joints measured by the author has an average azimuth of 150 or 155 degrees. Identical results were reported by Johnson and Stieglitz (1990), who measured the orientation oí 139 crevices and 864 fracture traces (Fig. 7) .

. Sorne of these bedrock lowlands are today occupied by cedar swamps, such as that between Ephraim and Baileys Harbor (Fig. 4 in road log). Others are partly occupied by small streams that flow southeastward into Lake Michigan. The" ends" of the lowlands on both sides of the península are drowried beneath !he waters of Lake Michigan and Oreen Bay, which have partially inundated the lowlands to form the many large bays and smaller coves that make Ihe shoreline one of Door County' s major attractions.

It is likely that thin tongues ofice ofthe Oreen Bay Lobe (in effect, small valley glaciers) crossed the penlnsula from northwest to southeast, filling and scouring these joint-controlled bedrock lowlands and temporarily segmenting the county into a string of nunataks, just shortly before general glaciation of the upland. Indeed, Chamberlin long ago reached a similar interpretation; he remarked that "the conclusion is forced upon the mind that the inlets are glacial troughs, fiords, perhaps, we should call them .. , formed ... by the passage of the ice across the penlnsula, forrning the indentations on the Oreen Bay side, in its ascent of the ridge, and those on the Lake Michigan side in its descent" (Chamberlin, 1877, p.205).

7

o • Measurements

(153 total)

Figure 6. Map and rose diagral11 showing orientations of joints in the Silurian dolomites of the Door Peninsula. (Adapted from Dutch, 1980, lIg. 3; data from Sherrill, 1978, and Dutch, 1980.)

Fracture Trace Orlentatlon 8&4 rneasuremantS

Figure 7. Rose diagram showing fracture-trace orientations in the dolomites of Door County. (From Johnson and Stieglitz, 1990, lIg. 3.)

8

GLACIAL LANDFORMS

Ground Moraine

Much of Door County can be c1assed as ground moraine, and it was mapped as such by Thwaites and Bertrand (1957, pI. 8). These workers a1so correctly observed that the ground moraine south of Sturgeon Bay consists of flat to gently rolling topography underIain by red glacial till, whereas the area north of Sturgeon Bay consists of very tbin buff-colored drift over bedrock. Because tbe glacial deposits are so tbin, it is generally difficult to determine how much of tbe landscape is bedrock controlled and what part is actually due to an irregular tbickness of drift.

Drumlins

Two areas of low-relief drumlins are present in Door County. One drumlin cluster, termed tbe Liberty Grove drumlin field (Schneider, 1989), is in tbe northern part of tbe county between Sister Bay and Rowleys Bay in tbe Town of Liberty Grove (Fig. 5 in road log). Many of tbese hills are only 3-6 m high, although a few of tbe more prominent forms have relief of 9-12 m. The orientation of tbe long axes oftbese drumlins averages aboutS. 15° E. Several display distinctasyrnmetric longitudinal profiles, having steeper north-facing slopes. All are inade of yellowish-brown pebbly loam Liberty Grove till, tbe type section of which is located in a road cut tbrough one of tbe drumlins. Altbough tbey are relatively small features and few in number, tbe drumlins are significant features of tbe local ground moraine.

The Liberty Grove drumlins were initially mapped and described by Kowalke (1952), and tbey are a1so shown·on tbe glacial map of tbe Door Peninsula by Thwaites and Bertrand (1957, pI. 8). In neitber of tbese papers do we fmd interpretive statements regarding tbe origin of tbe drumlins or tbeir significance to tbe regional glacial history. It is clear, h(:)wever, that botb tbe morphology and coniposition of tbe features are related to tbe advance of tbe Green Bay Lobe in late Woodfordian time.

The second area of drumlins is in soutbeastern Door County between Sturgeon Bay and Algoma; tbe larger of tbese features are irnmediately soutbwest of tbe city (Fig. 10 in road log). For tbe most part, tbese drumlins trend between S. 20" E. and S. 25° E. They seem to be composed largely of Liberty Grove drift. Several, however, carry a cap of red c1ayey till, and otbers are apparently buried more deeply beneatb a red-till cover. Thwaites and Bertrand (1957, pI. 8) mapped tbese drumlins up to and indeed even into an area tbey considered to be end moraine; no explanation is offered for tbis relationship.

End Moraines

No prominent end moraines, such as the Kettle Interlobate Moraine fart.her south, are present in Door County. Thwaites and Bertrand (1957, pI. 8), however, mapped an area of Cary (Woodfordian) end moraine soutb of Sturgeon Bay adjacent to tbe Lake Michigan shoreline and suggested (Thwaites and Bertrand, 1957, p. 851) that tbis belt might be eitber a phase of tbe Kettle Moraine or a retreatal moraine of tbe Lake Michigan Lobe. They further coinmented tbat tbe topographic expression of tbe moraine is weak because it is buried by a heavy cover of younger red clayey tUl. The northward continuation of tbe Kettle Moraine from Manitowoc and Kewaunee Counties is currentIy under investigation by tbe autbor. It is a1so possible tbat tbis belt represents either a northward continuation of tbe Two Rivers Moraine (Greatlakean age, Lake Michigan Lobe) or tbe eastern extent of tbe Glenmore till (Greatlakean age, Green Bay Lobe), or a combination of tbe two.

9

Thwaites and Bertrand (1957) a1so mapped several small patches of end moraine north of Sturgeon Bay. "A peculiar feature of these tracts," they stated, "is that many of them, despite their typical knob and kettle topography, trend east of south or parallel to the 'direction of the striae" (Thwaites and Bertrand, 1957, p. 853). They state further that a few of these tracts "Iook Iike true eskers, bu! the breadth and irregular outline do not support this interpretation." Again, mueh additional study is needed, but 1 would suggest that many of these landforms may be stagnant-ice features, perhaps crevasse fills, that formed normal to the Woodfordian ice margino

Severallow narrow end moraines are present, however, in northern Door County, but mapping of these features has not yet been completed. One such moraine crosses the peninsula between Egg Harbor and the south end of Kangaroo Lake; another appears to truncate spme of the Liberty Grove drumlins west of Rowleys Bay (Fig. 5 in road log). Rolling topography in the Town of Sevastopol may represent a somewhat broader moraine, but as stated aboye it is diffieult to determine whether the landscape is bedrock controlled or is due to an irregular thickness of drift.

Only one true esker is known to be present in Door County -- a large winding ridge southwest of Brussels (Fig. 8). The feature trends generally southeastward from south-central Union Township across the county line into northern Kewaunee County, where it follows a gap or reentrant angle in the Niagara Escarpment. Slightly less than half of its 10 km-Iength is in Door County. The feature has a maximum reJief of about 15 m, but its typical height is about lOor 12 m.

Other linear ridges apparently composed ·of sand and gravel were mapped by Thwaites and Bertrand (1957, pI. 8) as end moraine. As mentioned aboye, sorne of these may be stagnant-ice features -- perhaps crevasse fills, perhaps short eskers, but none have been studied. Several features that have been reported to me through the years as eskers are actually old beach ridges.

DOOR COUNTY SHORELINES

Door County shorelines, both modern and ancient, are as much a part of the geomorphology of the county as are the glacier deposits and landforms themselves. In fact, much of the hilly topography and interna! relief of the county is a direct result of lake history during late-glacial and postglacial time, when lake water covered not only the margins of the county but invaded interior lowlands as well. Indeed, at times the northern part of the county was an archipelago, consisting of a series of islands strung along the strike of the Niagara Cuesta.

Modern Shorelines

Clearly the most diagnostic aspect of the present-day Door County shoreline is it irregularity. Both the Lake Michigan and Green Bay coasts are characterized by numerous scallops -- bays and coves separated by bedrock headlands. Because of these many indentations, the county has roughly 400 km (240 miles) of coastline -- mote thanany other county in the conterminous 48 United States, despite its relatively small area of about 1,272 km' (500 square miles).

In other respects, however, the Green Bay and Lake Michigan shorelines are very different. The western or Green Bay eoast is charaeterized by pebble and eobble beaehes and by steep dolomite bluffs that define the Niagara Esearpment a10ng the western edge of the Niagara Cuesta (Figs. 1, 4, and 6 in road log). From Sturgeon Bay northward these bluffs rise from 40 to 55 m (130 to 180 feet) aboye water leve\. The full height of the escarpment cannot be seen, however, because the base of the escarpment

10

D

, 1

I 1 ',---t- - --1+7"- -1-7'-=0,_

---T 1 ~' 1\ -v~

1

f-~-

1

Figure 8. 10 fee!.

(

(

is commonly concealed beneatb tbe water planeo The floor of tbe Oreen Bay basin is generally between 20 and 25 m (65-80 feet) below water level; in some places tbe water is 9 to 12 m (30 to 40 feet) deeper. The total relief of tbe escarpment, tberefore, ranges from 60 to 90 m (200 to 300 feet). The rugged character oftbe Oreen Bay shoreline is well displayed in many places, particularly in Peninsula State Park (Fig. 4 in road log), at Ellison Bay Bluff County Park, at Deatb Door Bluff County Park (Fig. 6 in road log), "and at Boyer Bluff on Washington Island.

In contrast to tbe generally rugged and rocky Oreen Bay shoreline, tbe Lake Michigan coast is much more gentle. It is characterized by lower relief and by long stretches of sandy beaches and sand dunes, such as tbose at Newport State Park (Fig. 8 in road log) and Whitefish Dunes State Park (Fig. 9); tbe latter are tbe highest on tbe Wisconsin coast. Exposures of bedrock, tbough certainly not absent, are much less common, and dolomite bluffs, such as tbose at Cave Point (Fig. 9), are much lower and less continuous tban tbose along tbe Oreen Bay shoreline. Where bluffs exist soutb of Sturgeon Bay, as at Robert LaSalle County Park, tbey are composed of unconsolidated glacial deposits.

The contrast between tbe Oreen Bay and Lake Michigan shorelines and also tbe presence of corresponding bays on opposite sides of tbe peninsula was noted more tban a century ago by T. C. Chamberlin (1877, p. 204), who commented tbat " ... tbe peninsula Iying east of Oreen Bay merits special attention, by virtue of its peculiar features. The Oreen Bay side of tbe peninsula is high, bold, and precipitous, while tbe Lake Michigan shore is low and inconspicuous. But while tbe two sides are in striking contrast in tbis respect, tbey are consp.icuously similar in tbe deep indentations tbat characterize eitber side. And tbat which gives especial interest to tbis is tbe correspondence tbat exists between tbem -- tbey are in pairs. "

Abandoned Shorelines

The late-glacial and postglacial history of tbe Oreen Bay and I:ake Michigan basins isextremely complex and certainly is not yet fully understood. A comprehensive review of tbe late Wisconsinan and Holocene history of tbe Lake Michigan basin has been published elsewhere (Hansel and otbers, 1985), and tbe subject need not be discussed in detail here.

Abandoned shorelines of several late-glacial and postglacial lake phases are present tbroughout Door County. These former shorelines are represen(ed by botb erosional and depositional landforms, including terraces, wave-cut cliffs, sea caves, sand dunes, and numerous gravelly beach ridges and beach-dune ridge complexes. Several of tbe high dolomite bluffs along tbe Oreen Bay coast are marked by notched or stepped bluff profiles tbat record one or more high lake stages.

Many of tbe shoreline features were described more tban 85 years ago by J. W. Ooldtbwait (1907) in his now-classic bulletin on the abandoned shorelines of eastern Wisconsin. Unfortunately, many of tbe specific features noted by Ooldtbwait cannot be identified witb certainty today, mainly because tbey were described relative to cultural features tbat no longer exist (for example, Mr. Larson's house, Capt. Mike Anderson's hotel, Hanson's store).

Old shorelines are more abundant in tbe northern, narrow part of tbe county tban farther soutb, probably because of tbe northward convergence of tbe Lake Michigan and Oreen Bay basins. At Little Sister Bay, for example, twelve or thirteen beach ridges have been counted in a distance of about 300 m (1,000 feet) between tbe modern shoreline and tbe wave-cut bluff adjacent to Little Sister Cemetery.

The highest (and oldest) abandoned shoreline in Door County (Ooldthwait, 1907; Kowalke, 1947; Thwaites and Bertrand, 1957) has generally been considered to be tbat formed during tbe glacial Lake

12

I( Figure 9. Par! of Ihe racksonpor! 7.S-minule quadrangle rnap. Scale 1:24,000; conlour inlerval 10 feet. Clark Lake occupies a bedrock lowland and is isolaled from Lake Michigan by a rnassive dune field. The shoreline nor!heasl of Ihe dunes, including Ihe Cave Poinl headland, is defended by resistan! Silurian dolomi!e. Note the prominent Nipissing shoreline, capped in places by dunes, a! 600 fee!.

, _."-- -- -- - -

\

28

, ,

+

36

b1,'C,.ve Point

]]

"

+

'0

Algonquin phase of lake history, which is dated at about 11,000 yr B.P. In many places tbe Algonquin shoreline (as identified by earlier workers) is represented by a cobble beach, commonly obscured, at tbe base of a steep wave-cut cliff. Elsewhere it is marked by low beach ridges composed dominantIy of fine grave!. The most prominent shoreline, however, is tbat which formed during tbe Nipissing Oreat Lakes phase of lake history. The Nipissing phase is dated at 5,000-4,000 yr B.P. (Hansel and otbers, 1985). It is represented by a variety of landforms, notably beach ridges, shoreline dunes, and wave-cut terraces at an elevation of 183-184 m (600-605 feet).

Unlike older shoreline features, tbose of tbe Nipissing phase apparentIy have not been affected by isostatic rebound (Ooldtbwait, 1907; Thwaites and Bertrand, 1957; Hough, 1958), because tbe Nipissing hinge .line (zero isobase) is north of tbe Door Peninsula proper (Leverett and Taylor, 1915), barely crossing tbe northern part of Washington Island. Thus tbe features occur today at virtually tbe same elevation at which tbey were formed (Fig. 2 in road log). Older shorelines, however, occur at elevations aboye tbeir level of formation because tbey were uplifted and tilted as a resuIt of crustal rebound accompanying deglaciation. Thus tbe Algonquin shoreline, which was also formed at about 184 m (605 feet), is now found at an elevation of 186 m (610 feet) at Oreen Bay and rises northward to 189 m (620 feet) at SturgeOli Bay and. to about 200 m (658 feet) at Oarrett Bay west of Oills Rock (Ooldtbwait, 1907; Thwaites and Bertrand, 1957).

Shoreline features intermediate in age and elevation between tbe main Algonquin and Nipissing phases (Fig. 2 in road log) probably relate to tbe so-called late Algonquin (post-Main Algonquin) lakes tbat occupied tbe Oreen Bay, Lake Michigan, and Lake Huron basins as tbe margin of tbe Laurentide Ice Sheet witbdrew northward and uncovered successively lower outIets to tbe northeast in soutbern Ontario. At least five and possibly as many as seven probable late A1gonquin shorelines are present in Door County. Correlation of tbese shorelines has not yet been possible, however, because of tbe many inconsistencies and problems in identifying shorelines from place to place and tbe apparent lack of consistent altitudes from one locality to tbe next. Indeed, positive identification of even tbe Nipissing and main Algonquin shorelines is questionable in many places.

During and after tbe Nipissing transgression, tbe moutbs of several elongate bays, which probably occupied bedrock lowlands, were sealed off from Lake Michigan by tbe growtb of baymoutb bars and associated sand dunes to form inland lakes. These inelude Europe Lake near tbe tip of tbe peninsula (Fig. 8 in road log), Kangaroo Lake soutbwest of Baileys Harbor, and Clark Lake soutb of Jacksonport (Fig. 9). AlI are isolated from Lake Michigim by late Nipissing and post-Nipissing beach-dune complexes.

Otber bays or lowlands, instead of being cut off from Lake Michigan, have been partially filled in witb beach and dune deposits. These deposits commonly take tbe form of concentric arcuate ridges separated from each otber by shallow troughs, so as to form a corduroy-type topography. The ridge-and-swale complex at tbe head of Baileys Harbor owned largely by The Ridges Sanctuary is probably tbe best known example. A study by Stieglitz and otbers (1979) revealed 29 separate crests at The Ridges; tbe age and climatic significance of tbis ridge-and-swale complex was studied by Johnson

. and otbers (1990).

Similar ridge complexes occur at tbe head of Jackson Harbor on Washington Island, adjacent to tbe Mink River Estuary north ofRowley Bay, and at LilIy Bay. The most extenSive area of such features occurs at tbe moutb of Sturgeon Bay on botb sides of tbe ship canal between Portáge Point and Rocky Point (Fig 10); tbose on tbe north side of tbe canal are currently being studied by Curt Larsen. The ridges were formed in Holocene time, probably during periods of stability as crustal rebound occurred and tbe level of Lake Michigan gradually dropped from tbe Nipissing stage to its present leve!. Similar features are virtually absent along tbe Oreen Bay shoreline. A notable exception is tbe beautiful large

14

Figure 10. Part of Ihe Sturgeon Bay East quadrangle map. Scale 1:24,000; contour interval 10 feet. Ridge-an4-swale complex at the mouth of Sturgeori

~ Bay. The flat swampy areas north and south of tbe canal behind the ridge

~~ ;-. <I!"" e complex is probably the bes! preserved area of Nipissing.lake botlom along ~ Ihe westem sbore of Lake Michigan. Note the well defined Nipissing and

. Algonquin slllorelines.

·NI

/

spit called Idlewild that is still being built across Sawyer Harbor north of Potawatomi State Park at the entrance to Sturgeon Bay.

Although the main AIgonquin shoreline has long been considered to be the highest abandoned shoreline on the peninsula, traces of two higher shorelines (Fig. 5 in road log) have recently been identified (Schneider, 1988). 11Ie higher of these is at an elevation of about 225 m (740 feet), or 28 m (92 feet) aboye the nearby Algonquin shoreline at Ellison Bay. Here it is apparently truncated by a lower shoreline about 15 m (50 feet) aboye the AIgonquin. One can only speculate that these higher shorelines may correlate with older landforms of glacial Lake Chicago in the southern part of the Lake Michigan basin. 11Ie recognition of these older uplifted shorelines is tenuous, however, because of their similarity in topographic express ion to what are possibly upper valley walls of preglacial bedrllck valleys. A good example of one such feature can be seen behind the picnic area at Ellison Bay Bluff County Park.

It is possible, of course, that one of these higher features may represent the main AIgonquin phase and that the shoreline identified as the Algonquin by earlier workers may actually be a late AIgonquin (post-main AIgonquin) feature. 11Iis is not considered a likely possibility, however.

Problems in Identifying and Correlating Abandoned Shorelines

As inferred aboye, the identification and correlation of abandoned shorelines in the Door Peninsula is made difficult by many problems and complications, including the following:

(1) Direct tracing of individual shorelines over substantial distances is virtually impossible, either because the shorelines are discontinuous or their strength varies from place to place, or because property ownership and man-made structures preclude .continuous access.

Q-) Former shorelines are represented by both erosional and depositionallandforms, including terraces, wave-cut· cliffs, sea caves, sand dunes, and numerous gravelly beach ridges and beach-dune ridge complexes·. 11Ius a shoreline formed during a particular lake stage may be represented by different geomorphic features at different places. For example, at one locality a specific shoreline may be represented by a wave-cut bluff but elsewhere by a beach ridge or a gravel bar.

(3) 11Ie number of abandoned shorelines is not constan!. Environmental conditions very likely were not everywhere favorablll for the formation of coastal landforms during any given lake stage. In addition, many older shore features have undoubtedly been destroyed or are obscured by later events. Sorne shoreline features, especially gravel bars and beaches, have been partially destroyed by human activities. Furthermore, old shorelines are more abundant in the narrow northern part of the county than farther south.

(4) 11Ie elevation of most shorelines also is not constant due to crustal rebound. 11Ie main AIgonquin and late AIgonquin strandlines have been uplifted to the north, but not uniformly so. As Goldthwait (1907, p. 102) pointed out, the rate of uplift appears to increas.e from south to north. 11Ie Nipissing and younger beaches are virtually horizontal.

(5) Although many ofthe specific shoreline features noted by Goldthwait in the early 1900s can be identified with certainty today, a great many others cannot be so identified, mainly because they were described relative to cultural features that no longer exist.

16

¡

(6) Many shoreline features are clearly compound or composite features, having been formed during two or more lake levels. Wave-cut bluffs and even wave-cut terraces, for example, may be the product of erosion during more than one lake phase.

(7) Difficulty in distinguishing between wave-cut terraces and stripped surfaces on more resistant units in the bedrock.

(8) Difficulty in distinguishing between wave-cut bluffs and possible bedrock valley walls of preglacial streams.

(9) Difficulty in distinguisbing between wave-cut features and glaciokarst features such as kamenitzas and schichttreppen (Rosen, 1984; Johnson and Steiglitz, 1990). See paper by Stieglitz and Schuster elsewhere in this guidebook.

(10) Lack of consistent results and/or apparent imprecision in determining shoreline elevations with the Paulin altimeter. Although the entire area is covered by 1:24,000 scale topographic maps with a contour interval of 10 feet, many shorelines cannot be shown on topographic maps at this scale and contour interval, especially if the feature is a composite shoreline.

(11) Considering the problems that have been encountered using a modern altimeter, the precision of Goldthwait's elevation measurements may be fairly questioned.

(12) Judging from Goldthwait's descriptions, as well as from personal knowledge, the country appears to have been more open and accessible during the early part of the century than it is today.

(13) Radiometric dates are not available; datable materials relative to shoreIine features have hot been found.

REFERENCES CITED

Chamberlin, T. C., 1877, Geology of eastern Wisconsin, in Geology of Wisconsin, V. 2, p. 91-405. Dutch, S. l., 1980, Structure and landform evolution in the Green Bay, Wisconsin area, in Stieglitz, R.

D., ed., Geology of eastern and northeastern Wisconsin: 44th Annual Tri-State Geological Field Conference, p. 119-134.

__ o _' 1989, Evolution of the Green Bay lowland, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Conference Proceedings, p. 26.

Goldthwait, J. W., 1907, The abandoned shore lines of eastern Wisconsin: Wisconsin Geological and Natural History Survey Bulletin 17, 134 p.

Hansel, A. K., Mickelson, D. M., Schneider, A. F., and Larsen, C. E., 1985, Late Wisconsinan and Holocene history of the Lake Michigan basin, in Karrow, P. F., and Calkin, P. E., eds., Quaternary evolution of the Great Lakes: Geological Association of Canada Special Paper 30, p. 39-53.

Hough, J. L., 1958, Geology of the Great Lakes: University of Illinois Press, Urbana, 313 p. Johnson, S. B., and Stieglitz, R. D., 1990, Karst features of a glaciated dolomite peninsula, Door

County, Wisconsin: Geomorphology, V. 4, p. 37-54. Johnson, T. C., Stieglitz, R. D., and Swain, A. M., 1990, Age and paleoclimatic significance of Lake

Michigan beach ridges at Baileys Harbor, Wisconsin, in Sclineider, A. F., and Fraser, G. S., eds., Late Quaternary history of the Lake Michigan basin: Geological Society of America Special Paper 251, p. 67-74.

17

Kluessendorf, Joanne, and Mikulic, D. G., 1989, Bedrock geology of the Door Peninsula of Wisconsin, in Palmquist, J. e., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p.' 12-31.

Kowalke, O. L., 1947, Highest abandoned beach ridges in northern Door eounty, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Transactions (for 1946), v. 38, p. 293-298.

__ ' 1952, Location of drurnlins in the town of Liberty Grove, Door eounty, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Transactions, v. 41, p. 15-16.

Leverett, F., and Taylor, F. B., 1915, The Pleistocene oflndiana and Michigan and the history of the Great Lakes: U.S. Geological Survey Monograph 53,529 p.

Martin, Lawrence, 1916, The physical geography of Wisconsin: Wisconsin Geological and Natural History Survey Bulletin 36, 608 p. (Second edition published in 1932, third edition in 1965.)

Rosen, e., 1984, Karst geomorphology of the Door Peninsula, Wisconsin: unpublished M.S. thesis, University of Wisconsin-Milwaukee, 119 p.

Schneider, A. F., 1988, Late Quaternary shorelilles of the Door Peninsula, Wisconsin: American Quaternary Association Program and Abstracts, 10th Biennial Meeting, University of Massachusetts, Arnherst, p. 148.

__ ' 1989, Geomorphology and Quaternary geology ofWisconsin's Door Peninsula, in Palmquist, J. e., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 32-48.

Sherrill, M. G., 1978, Geology and ground water in Door eounty, Wisconsin, with emphasis on contamination potential in the Silurian dolomite: U. S. Geological Survey Water-Supply Paper 2047,38 p.

Stieglitz, R. D., 1989, The geological environment and water quality in Wisconsin's Door Peninsula, in . Palmquist, J. e., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 82-97.

Stieglitz, R. D., Metzner, D. e., and NewcolÍlb, W. D., 1979, Sedimentology and post-glacial history . of abandoned beach-dune ridges in northeastern Wisconsin: Geological Society of America

Abstracts with Programs, v. 11, p. 258. . . Thwaites, F. T., and Bertrand, Kenneth, 1957, Pleistocene geology of the Door Peninsula, Wisconsin:

Geological Society of America Bulletin, v. 68, p. 831-880. Wielert, J. S., 1980, The late Wisconsinan glacial lakes of the Fox River watershed, Wisconsin:

Wisconsin Academy of SCiences, Arts and Letters Transactions, v. 68, p. 188-201.

18

I

WHEN GREEN BAY WAS A VALLEY: THE AV TRAIN-WIllTEFISH-GREEN BAY SPILLWAY

John D. Hughes Department of Geography, Earth Science, Conservation and Planning

Northern Michigan University Marquette, Michigan 49855

INTRODUCTION

Near tbe close of tbe Wisconsinan glacial stage, as tbe edge of tbe shrinking Laurentide Ice Sheet was leaving tbe nOrthern Great Lakes, a high ancestral stage of Lake Superior began draining across tbe Northern Peninsula of Michigan toward Green Bay. The timing of tbis event was coincident witb Lake Chippewa, tbe lowest stage tbat ever occupied tbe Lake Michigan basin. Therefore, when tbe fiood from tbe north had crossed tbe breadtb of tbe peninsula it continued across tbe fioor of a valley tbat today contains tbe bay of Green Bay. This paper describes tbe Au Train-Whitefish lowland (Fig. 1) and provides a summary of scientific attention tbat tbe channel has received, much of it of a speculative nature. The paper continues witb a description of tbe now-submerged extent of tbe channel in lhe bay fioor (Fig. 2), including an area where it passes tbrough tbe highland of tbe Niagara Cuesta midway between tbe Door Peninsula and its counterpart in Michigan, tbe Garden Peninsula. The channel is followed to its terminus at a massive Chippewa-Ievel delta on tbe east slope of tbe cuesta near Washington Island. The paper closes witb a history of tbis period when tbe ice sheet was melting from northern Green Bay and Lake Superior -- a period tbat encompasses tbe active tenure of tbe Au Train-Whitefish­Green Bay spillway.

THE AU TRAIN-WHITEFISH LOWLAND

The Au Train-Whitefish lowland extends from Au Train Bay 60 km soutbward to tbe head of Little Bay De Noc (Fig. 1). The northern 21.3 km of tbe lowland, including Cleveland Cliffs Basin, is drained by tbe Au Train River. The soulhern 38.7 km occupies part oftbe Whitefish River's watershed, allhough clearly it has been channeled by a vastly greater fiow of water Ihan Ihe discharge of tbe present river.

Relic channels begin in Ihe vicinity of Ihe storage basin from where Ihey grow in widlh from slightly more Ihan 1 km to a maximum breadlh of 7 km in an area located about 11 km north of Little Bay De Noc. It is doubtful Ihat Ihe water Ihat cut Ihe channels ever occupied tbe full widlh of Ihe lowland at one time. Evidence for tbis assertion is demonstrated by tbe valley's transverse configuration, especially where it approaches its greatest widlh. North from Little Bay De Noc tbrough a distance of 27 km, profiles across Ihe lowland show Ihat Ihe fioor near tbe western channel bank consistently is about 12 m higher Ihan is Ihe easternmost 1 km of channel fioor. It seems tbat channel cutting started wilh an initial finod tbat poured southward along what i8 now Ihe western part of the lowland. Then as incision occurred, Ihe active channel shifted across Ihe gently soulheasterly sloping bedrock surface. This interpretation also provides an explanation for Ihe greater height of tbe lowland's east bluff, which is found on any east-west traverse to be two to six times higher Ihan tbe west bluff until soulh of Rapid River. There, bluffheights become nearly equal, owing to tbe increasing tbickness of outwash into which Ihe west side of tbe valley has been cut.

The natural divide between Ihe Au Train and Whitefish rivers lies at Ihe dike which forms tbe soutb end of Ihe Cleveland Cliffs Basin. Elevation of Ihe divide is 235 m A.T. or 51 m aboye Lake Superior and 58 m aboye Little Bay De Noc (Lake Michigan). The divide once was slightly higher and farther north because terraces as high as 250 m A.T. parallel Ihe storage basin northward an additional

19

Slapneck el.

AU TRAIN- WHITEFISH SPILLWAY

Aapld A.

SCALE

kllometers

o • 10

elevation in meten

Au Train lake

eleveland eliffs Sasin

•

Whitefish R.

LitUo

Bay O. Noo

Figure 1. The Au Train-Whitefish Spillway.

20

,. I

7 km. PostgIaciaI erosion by tbe Au Train River has obliterated evidence of tbe former divide. Through headward eros ion, IargeIy accomplished by spring sapping, tbe Au Train River has shifted tbe divide as much as 14 km to tbe soutb. While expanding its watershed, tbe Au Train River has captured tbree former tributaries of tbe Whitefish River -- Slapneck, Johnson, and Joe Creeks (Fig. 1).

Average gradient of tbe Whitefish River portion of tbe lowland is 1.5 mlkm. Locally, however, tbe gradient varies considerably from tbis value, ranging between a low of 0.5 m/km tbroughout tbe tirst 6 km soutb of tbe divide and a high of 2.6 m/km tbroughout tbe following 3 km. Changes in gradient, altbough not of tbis magnitude, continue along tbe remaining Iowland. Generally, lower gradients are found witbin 15 km of Little Bay De Noc. AII gradient fluctuations are probably reIated to irregularities in tbe bedrock surface.

The floor of tbe Whitefish portion of tbe 10wIand is usually underlain by tbin deposits of graveI or till over carbonate bedrock. Commonly, where tbe overburden is less tban 1 m tbick and tbe underlying bedrock prevents drainage, tbick extensive muck soils have deveIoped such as the Catbro, Tacoosh, and Chippeny series. The most common of tbese, tbe Chippeny, is cIassitied by tbe Soil Conservation Service as a euic Litbic Borosaprist. The SCS description of tbe Chippeny soil notes tbat "deptb lo limestone bedrock ranges from 20 to 51 inches but is (pre)dominantly 20 to 40 inches." In one representative profile (sec. 3, T. 41 N., R. 21 W., Delta County), in which bedrock was' encountered 28 inches below tbe surface, 20 inches of sapric fibrous material overlies eight inches of sticky and mildly alkaline silty cIay Ioam (U.S.D.A., 1977, p. 24). The silty cIay loam was probably formed by weatbering of limestone bedrock and possibly overlying limestone detritus in tbe post-channeling periodo

Most muck and peat land in tbe Whiiefish lowland is covered by dense swamp forest. The common vegetation types found here are arborvitae, black spruce, balsam tir, and numerous black ash, red maple, white birch, hemlock, and white pIne. In peaty areas aspen, alder, willow, and red-osier . dogwood occur.

Sorne better drained rock or beveled ground-moraine areas occur in tbe western half of tbe Whitefish lowland. These account for about 15 percent of tbe total area and are nearly equally divided between limestone rock land and shallow and often excessively stony till.

In about half of tbe Whitefish lowland, gravel channel bars conceaI tbe bedrock surface, giving tbis afea most of its relief. Many bars rise 3-4 m aboye tbeir bases. The largest (on tbe east side of tbe 10wIand 10 km north of LittIe Bay De Noc) has a height tbat slightly exceeds 10 m. Usually, bars are capped by tbe Kiva soil series which is cIassified as a Typic Haplorthod (U.S.D.A., 1977). The most common vegetation on tbe channeI bars is second-growtb hardwood, mostly aspen, red mapIe, and cherry; red and white pine also occur, but only as wideIy scattered individuals.

HISTORY OF SCIENTIFIC ATTENTION

Possibly because earIy traveIers in tbe northern Great Lakes region used water transportation, tbe Au Train-Whitefish Iowland escaped tbe attention of early scientists such as Douglas Houghton. However, tbe beginning of copper mining in tbe Keweenaw Peninsula in 1844, followed several years later by iron mining west of Marquette Bay, spurred further interest in Michigan's Northern Peninsula. Several parties of surveyors and geologists, in search of otber mineral weaItb, penetrated its forested interior. Followingtbese excursions (1850-1910), several reports appeared tbat inventoried tbe region's minerals, soils, vegetation, and physiography. These reports often combined comments about relic beaches, glacial moraines, and glacial outwash. The first known observation of tbe Au Train-Whitefish lowland appeared in Foster and Whitney's report (1851), in which E. Desor noted tbat tbe Whitefish River's valley has " ... a great uniformity and monotony of aspect. Along tbe course of tbe White-fish,

21

the drift has been excavated so as to leave a wide swamp on each side, in which the rock Hes near the surface. "

Winchell (1871) summarized the field experiences ofWadsworth in the Au Train-Whitefish area. Re identified the channel as having once carried the outflow of Lake Superior and described numerous depositional and erosional features that had been formed within the channel by that former high-volume discharge.

In 1904 Russell began mapping the surticial deposits ofthe Northern Peninsula of Michigan. The results were to be used in preparing a map of the surticial deposits of the península. FoIlowing a reconnaissance of the south shore, he wrote a short section in his report about the yalley of the Whitefish River. Apparendy, he faUed to see any evidence of channel erosion and interpreted the yalley floor to consist of a thin layer of ground moraine (till) deposited on bedrock. Re identified the yalley sides as kame terraces that had formed along the sides of a yery narrow ice lobe that extended across the width of the peninsula.

In 1905 Frank Leyerett continued his inyestigation of moraines and ancient shorelines in the Great Lakes region by extending his work into the Lake Superior district. Between 1905 and 1919 he spent sixteen months in the Northern Peninsula of Michigan and the Lake Superior drainage basin portions of Wisconsin and Minnesota. Ris work appeared in a report Moraines ami shorelines of the Lake Superior region (Leyerett, 1929).

Leyerett's priínary hypothesis was that the main: Algonquin stage, which left strongly developed shorelines on the slopes bordering Lakes Michigan and Ruron, eventually extended into the entire Lake Superior watershed (Leyerett, )929, p. 63-68). Re belieyed that as the glacial margin retreate'd, it permitted Lake AIgonquin's surface to spread across the eastern part of the Northern Peninsula, submerging all but tbe highest land areas. Ineyitably, retreat from tbe northern slope of tbe peninsula east of tbe Keweenaw Peninsula opened eastward-sloping channels along the margin of tbe ice in the Ruron Mountainand Marquette area. These channels permitted Lake Pulutb, an expanding water body in tbe western part of tbe Lake Superior basin, to drain eastward into Lake Algonquin. Leyerett repeatedly suggested that tbe Au Train-Whitefish lowland probably served as part of tbis system of outlets,at least some of the time, and in one place in his report he refers to tbe lowland as tbe Au Train­Whitefish outlet (Leyerett, 1929, p. 63,64,66). According to Leyerett, Lake Algonquin persisted untU after tbe margin of tbe ice sheet had retreated to tbe northeast of Lake Superior (Leyerett, 1929, pI. 7). Leyerett acknowledged that a lowland northeast of Lake Ruron leading past North Bay to tbe Ottawa Riyer could have been depressed by the weight of tbe ice sheet to an eleyation considerably lower tban tbe Kirkfield-Trent oudet, tbe oudet through which Lake Algonquin had drained. Therefore, Leyerett reasoned tbat the North Bay oudet must haye remained coyered by glacial ice whUe retreat from tbe Lake Superior basin was occurring (Leyerett, 1929, p. 68).

In otber sections of his report it appears that Leyerett at times regarded tbe lowland quite differently. In an earlier passage he had written: .

"Along the lowest part of the Au Train-Whitefish depression there is a strip of nearly bare rock from tbe crossing of tbe Munising, Marquette and Soutbeastern RaUway to the head of Little Bay De Noc. Rere the rock may have been denuded of some of its drift coyer by tbe passage of lake currents through the narrow strait tbat in Lake Algonquin time led from tbe Lake Superior Basin to tbe Green Bay Basin ... " (1929, p. 45).

Consistent with tbis reasoning, his explanation for tbe high banks on each side of Little Bay De Noc paralleled tbat of Russell (1904). Re felt it was " ... not improbable tbat tbe ice lobe was occupying tbe north end of tbe bay while tbe outwash was being deposited at its borders." (Leyerett, 1929, p. 43).

22

When Leverett completed Plate 2 (map showing areas formerly covered by glacial lakes of northeastern Minnesota, northern Wisconsin, and Northern Peninsula of Michigan), he indicated that the lowland had been occupied by a strait of Lake AIgonquin and apparently interpreted the channel banks to have been cut by wave action. Since he had previously observed tilt rates on the AIgonquin water plane in the eastern part of the peninsula (averaging about 0.75 m/km or 4.0 ft/mi), he was surprised by the values he obtained from the northern section of the Whitefish portion of the lowland,

"The most remarkable rise in the upper shoreline that has yet come to notice is found along the borders of the Au Train-Whitefish Valley. From a point near the Delta-Alger county line northward to Chatham there is a rise of 93 feet in a distance of 13.5 miles (28.3 meters in 21.8 kilometers), or about 7 feet to the mile (1.32 meters to the kilometer). In the southern 8 miles of the line the rise is 65.5 feet (20 meters in 5 kilometers), or slightly more than 8 feet to the mile (1.51 meters per kilometer), and in the northern 5.5 miles the rise is 27.5 feet (8.4 meters in 8.9 kilometers), or 5 feet to the mile (0.94 meters per kilometer). This most rapid rate of tilting is in a narrow passage onIy 1 to 1 1/2 miles wide (1.6 to 2.4 kilometers). Farther north where the rate ís lower, the waters had greater width."

• Leverett attempted to explain these gradients, which are much too steep to be tilt rates, by

invoking the possibility that a transitional stage occurred north of the divide in the course of the lowering of waters from Lake Duluth to the AIgonquin leve!. He suggested that the steeper gradient may have been produced by water spilling from the transitional lake to the level of Lake AIgonquin through a blockage of drift deposits in southern AIger County. If that were tlIe cas!l, Lake AIgonquin never could have extended northward as a strait through the entire length of the Au Train-Whitefish lowland.

When Jack Hough's Geology of the Great Lakes appeared in 1958, it ineluded a section titled "History of Lake Stages." Hough based this sectlon on observations of dozens of geologists made over a period extending back to the 1850s and added to these new data generated by his own field research. In a sub-section titled "The Maximum Extent of the Main Algonquin Stage" he took exception to Leverett's extension of the AIgonquin stage into the Lake Superior basin. In this section he introduced his own evidence, collected in an area a short distance north of Sault Ste. Marie, Ontario, which proved that the glacier in that locality was conterminous with Lake Algonquin. AIso, examination of Leverett's Algonquin beaches in the Marquette and Keweenaw area by Hough and others has proven, without exception, that these are not beach-related features but rather various glaciofluviallandforms completely unrelated to shore action.

In his surnmary of events in the Superior basin, Hough (1958) agreed with Leverett's reasoning that retreat of the ice margin down the slope in the Huron Mountain and Marquette areas opened a series of outlets for the western Lake Superior basin. Hough suggested that all this drainage eventually f10wed through the Au Train-Whitefish lowland. UnlikeLeverett, however, Hough believed that by the time an unbroken channel opened between western Lake Superior and the head of the Au Train-Whitefish outlet the main AIgonquin stage had dropped to one of the post-Algonquin levels in the Michigan and Huron basins. Hough's Figure 71 (1958, p. 294) shows a post-Duluth stage in the western basin of Lake Superior discharging along an imprecisely located channel to post-Algonquin "upper group" lake stages in the Michigan and Huron basins. In Figure 71 the ice margin is shown covering the northern slope of the peninsula between the Au Train-Whitefish lowland and the St. Marys River. Hough proposed that at sorne time retreat of the ice sheet's margin from that slope would have created a confluent water surface extending throughout the Michigan, Huron, and Superior basins. He admitted that he lacked enough data to make the correlation and simply left the subject for future study.

Hough's Figure 72 (1958, p. 295) shows a great change in the ice margin's location from the position it had held in Figure 71. It shows complete withdrawal of ice from Lake Superior and the area

23

a10ng the Sto Marys River. In the east the ice margin is shown to have retreated from the AIgonquin and Haliburton Highland, north of Lake Ontario, to the south slope of the North Bay outlet. Ice withdrawal from this slope gradually opened several outlets, causing a series of progressively lower stages to occupy the Michigan and Huron basins. One of these stages, Lake Payette, might have been about 30 m below the present lake surface at Washington Island. This elevation would have placed most of the floor of Green Bay aboye lake level and exposed it to seour by the various tributary rivers such as the Fox, Oconto, Peshtigo, Menominee, Escanaba, and Whitefish.

While condueting research in the Keweenaw Peninsula, Hughes (1963) noticed that relie beaehes as high as 185 m aboye Lake Súperior are well displayed on the peninsula's west side, but they are absent on its east slopes with the exeeption of the relatively low (8 to 11 m) Nipissing beach. Hughes, who started his research before Hough's book was published, tried to explain the absence of the AIgonquin shoreline in the Keweenaw Peninsula by extending his own research eastward. He made a reconnaissance of an area from east of Munising and south of Au Train Bay southward to Little Bay De Noc. He a1so used the largest scale maps available (1:250,000) and charts of Green Bay and Little Bay De Noc. His research led him to propose that glacial ice completely filled the Superior basin east of the Keweenaw Peninsula during the time the main AIgonquin and post-Algonquin "higher group" stages occupied the Michigan and Huron basins. Using lake charts, Hughes identified a well-defined channel in the floor of Little Bay De Noc and Green Bay that can be traced eastward into Lake Michigan east of Washington Island. There it ends at a depth of about 50 m. That depth correlates very well with a projection of the surface ofLake Chippewa, the lowest stage that ever occupied the Lake Michigan basin. Lake Chippewa, created by withdrawal of the ice margin from the North Bay outlet, drained eastward through the Mackinac River to Lake Stanley, an even lower stage thªt at this time occupied the lower parts of the Lake Huron basin (Stanley, 1938).

Hughes proposed that the edge of the ice sheet remained on the north slope of the Northern Peninsula of Michigan until sorne time following complete deglaciation of the North Bay outlet. As the ice margin was melting from the North Bay outlet and the stage that occupied the Lake Michigan basin was being lowered below present lake level, the glacier margin in the Huron Mountain and Marquette area a1so withdrew. This permitted the body of water in the western Lake Superior basin to flow through the Au Train-Whitefish outlet and continue across the floor of Little Bay De Noc and Green Bay. The discharge through that oudet ended when further recession ofthe glacier's margin opened a series of low­level ice-marginal outlets east of Munising. These outlets diverted drainage toward the Sto Marys River. Flow along the ice margin probably accelerated its retreat. Soon, withdrawal of the margin from the slope of land linked the western body of water in the Superior basin with Lake Minong, a low stage that had been confined to the extreme southeast corner of the Superior basin (Drexler et al., 1983).

This sequence of events for the northern Great Lakes differs significantly from Hough's Figures 71 and 72, which show that ice left the North Bay oudet following its disappearance from the Lake Superior basin. Hough's timing of events would neither permit the erosion of a gorge across the floor of Green Bay, nor channeling of the southern 10 or 15 km of the Whitefish lowland. Also, because his Figure 71 shows the sub-Duluth stage outlet terminating in one of the post-Algonquin "upper group" stages about lO or 15 km north of Little Bay De Noc, there should be, in that area, a massive delta dissected by the modern Whitefish River. An exhaustive search of the entire length of the Whitefish River and lengthy perusals of soil maps and new large-scale topographic maps demonstrate that a delta does not existo

Drexler (1981, p. 262) challenged Hughes' belief that the Au Train-Whitefish channel can be traced to the Chippewa stage at a depth of 49 m beldw Lake Michigan. Drexler wrote:

"The present writer, however, has reviewed the lake charts for that area and believeS the channel described by Hughes was largely cut by the Escanaba River because the

24

channel geometry visible from lhe charts resembles very closely lhat of lhe modern Escanaba River channel and differs strongly from lhat of lhe Au Train-Whitefish channel."

Instead, he proposed lhat lhe outlet channel can be traced to a deplh of only 33 m, which is lhe same as lhe level of Lake Sheguiandah, anolher low stage in lhe Michigan and Huron basins.

However, it seemed lhat little could be learned from lake charts about lhe channel in lhe floor of Oreen Bay except lhat lhere appeared to be a deep and probably continuous channel extending from Little Bay De Noc to Lake Michigan. Below lhe 5-falhom (30-foot) isobalh only spot deplhs are given on charts. These are few and far apart and consequentiy of little use when attempting to determine lhe shape of bottom features. In 1968 Hughes obtained U .S. Lake Survey field sheets for Oreen Bay. Each field sheet has a scale of 1 :40,000 and contains an extremely large number of spot deplhs; most of lhese are closely spaced. Hughes contoured lhe five field sheets, which provide coverage of most of lhe bay, at a 5-foot-isobalh intervalo The result clearly shows a trench cut 40 to 90 feet below lhe floor of Oreen Bay lhat is at least as wide as lhe modern SI. Clair or Detroit Rivers (Fig. 2). Its channel bottom possesses lhe same degree and kind of unevenness lhat is characteristic of lhese two rivers.

THE OREEN BA Y SUBMEROED CHANNEL

The head of Little Bay De Noc has been filled wilh deltaic sediment carried to it by lhe Whitefish and Rapid Rivers (Fig. 1). The marshy delta lhey have built no longer forms lhe bayhead because it is bordered to its soulh by Oarth Point, a sandy spit be\ng built westward from lhe east shore of lhe bay .

. Presently, lhe channeled floor of lhe bay appears abruptly at lhe foot of lhe soulh slope of lhe spit in a 4- or 5-meter water deplh.

From lhe head of Little Bay De Noc, lhe channeled portion of lhe floor gradually deepens to 11 m in a distance of 6.5 km. Throughout lhis section lhe channel has a widlh of 2 to 3 km. At Oladstone, Michigan lhe west channel bank swings suddenly eastward, narrowing lhe channel widlh to only 600 m where it squeezes past Saunders Poinl.

In lhe 12-km reach of channel between Saunders Point and Escanaba's Sand Point (Fig.2) lhe channeled bay floor expands to a maximum widlh of 5.5 km narrowing to less lhan 1 km where it passes Sand Poinl. The soulhward channel gradient observed in lhe first section continues and lhe deplh increases to nearly 12 m. Here, lhe two sides of lhe channeled area are marked by clearly defined bluffs lhat rise aboye lhe bottom almost vertically 7 or 8 m.

Soulh of Sand Point a markedly asyrnmetrical reach of channel bears due soulhward for approximately 25 km. Along a typical cross profile of lhe channel, at a place where Oreen Bay has a deplh of 18 m, lhe east channel bank is only 7 m deeper. To lhe west, however, lhe channeled floor drops· an additional 15 m in a distance of 5 km lo a deplh of 40 m. The lowel¡t part of lhe channel has a widlh of about 0.75 km and lhe west bank rises aboye it steeply, 22 m. In 1970 Hughes had an opportunity to examine a seismic profile (Wold, 1970) lhat crosses lhis part of lhe submerged channel. The profile shows lhat overburden forms bolh channel banks, wilh lhe sloping bottom consisting of bedrock. The bedrock surface continues to descend westward from lhe west channel bank. The seismic profile indicates lhat lhe asyrnmetrical shape of lhe valley was caused by a westward migration of lhe channel along lhe sloping bedrock surface as channel deepening tookplace. This process caused continuous undercutting of lhe west bank.

25

Twenty-five kilometers soulh of Sand Point Ihe west bank swings to Ihe east, where Ihe channel narrows to less Ihan 0.5 km, its floor deepens to 44 m, and Ihe valley becomes syrnmetrical. Tbis section of channel continues soulh-soulhwestward for 5 km and Ihen begins a smoolhly sweeping bend toward Ihe east Ihat has a 5-km radius of curvature. Tbis curving section of channel continues for 12 km to Washington Island, where Ihe channel just clears Ihe island's northwest cape known as Boyer Bluff (Fig. 2). Tbere, on1y 300 m from Ihe shore, Ihe water delllh in Ihe channel is more Ihan 50 m.

Wbere Ihe channel reaches Boyer Bluff its bearing is almost northeast, but at Ihe north tip of Ihe cape it bends sudden1y toward Ihe east and Ihen begins anolher gradual curve toward Ihe northeast for

. 8.5 km until it passes Ihe north end of Rock Island at Pottawatomi Point (Fig. 2). Tbrough Ihe curving and generally easterly trending sections, Ihe widlh of Ihe channel varies from 1.5 to 2.25 km.

Tbe field sheet for Lake Michigan east of Pottawatomi Point has a scale of 1:80,000, which is too small to permit contouring of Ihe channel since Ihe deplh values wilhin and near Ihe channel are too few and widely spaced. Nevertheless, Ihere are sufficient numbers of large deplhs, comparable to Ihose in Ihe channel west of Rock Island, to permit it to be traced to its moulh.

At Pottawatomi Point Ihe channel begins a tight curve around Ihe east side of Rock Island, Ihe first part of a 17 -km it passes between Rock and Washington Islands to Ihe west and Fish Island and Fisherman Shoal to Ihe east (Fig. 2). Tbroughout Ihe final few kilometers, Ihe channel trends soulheastward until it ends in 49 m of water, 10 km east of Washington Island's Soulh Point. Tbe deepest recorded point in Ihe channel is 52.4 m, between Fisherman Shoal and Washington Island, about 6 km upstream from Ihe channel's mOlllh.

SUBMERGED DELTA IN LAKE MICHIGAN

Where Ihe submerged channel ends in Lake Michigan, isobalhs outline a prominent bulge on Ihe lake floor Ihat is interpreted to be Ihe channel's delta. From Ihe channel's terminus Ihe delta slopes gradually eastward 16 km to a deplh of about 54 m where Ihe gradient abruptly increases. Tbe western edge of Ihe delta extends 30 km along Ihe Lake Chippewa shoreline. Tbe average deplh on Ihe delta's upper surface is 52 m, allhough Ihe surface is not flat. Tbe pattern of deplhs suggest Ihat at least two distributary channels cross Ihe delta, but Ihe field sheet lacks enough data for Ihis to be confirmed.

Tbe delta's foreslope descends steeply to deplhs ranging from 137 to 165 m and possibly deeper. Total area of Ihe delta is 390 km2

• If Ihe average Ihickness of Ihe delta is 24 m, its volume might be as great as 9.36 x lO' m'.

CHRONOLOGY OF GLACIAL EVENTS

Until Ihe 1970s, it was generally accepted Ihat all glacial landforms in northeastern Wisconsin and Ihe Northern Peninsula of Michigan originated during Ihe recession of Ihe Wisconsinan ice sheet from Ihe terminal position of Greatlakean ice near Two Rivers and Fond du Lac (11,850 years ago). It was Ihought Ihat wilhdrawal of Ihe ice proceeded moderately rapidly, except during several stillstands of Ihe margin when a number of end moraines and many outwash aprons were built. Hough (1958) placed Ihe glacial margin across Ihe northern part of Michigan's Northern Peninsula during Ihe time of Ihe main AIgonquin and post-A1gonquin "higher group" stages, but he could on1y speculate about Ihe absolute time of Ihat periodo Saarnisto's (1974) carbon dates from basal organic sediments in rock-basin lakes and pollen-stratigraphíc studies led him to propose Ihat a previously undetected pause, or at least slowing in Ihe rate of ice retreat in Ihe Lake Superior region, 11,000 to 10,100 years ago, should be named Ihe Algonquin Stadial. Saarnisto placed a minimum age of 11,000 years on bolh Lake Dululh and Lake

26

l·

THE SUBMARINE VALLEY

IN THE FLOOR

OF GREEN BAY

~ -N-

~ SCAlE

.. Ktl~lfIllt ..

Figure 2. The submarine valley in the 1100r of Green Bay.

27

AIgonquin and determined that the ice border had retreated to the north shore of Lalce Superior by 9,500 years ago. He believed that post-Duluth stages in the Superior basin and post-Algonquin "higher group" stages in the Michigan and Huron basins had existed at the same time, but separate!y, as the glacier slowly receded from the Northern Peninsula of Michigan during the AIgonquin Stadial. The discovery in 1976 near Marquette, Michigan of an interstadial forest that is younger than the Two Creeks forest suggests that a previously undetected glacial readvance may be partly responsible for the evidence that Saarnisto interpreted as prooffor slow retreat.' Futyma (1981), through his research in the eastern part of the Northern Peninsula has reduced the time of extinction of main Lake AIgonquin and Lalce Duluth stages to 10,600 and 9,900 years, respectively.

Withdrawal of Greatlakean ice from Michigan's Northern Peninsula must have talcen place during the last part of Saarnisto's period of slow retreat punctuated by frequent marginal stillstands. This occurred between 11,000 and 10,100 years ago, a time when, according to Saarnisto, tundra vegetation still dominated the Lake Superior .region. Retreat of the ice sheet's margin continued untí! it had withdrawn at least as far as the northern part of the Superior basin by 10,100 yr B.P., placing it far enough from the south shore to permit a rapid tempering of the climate, and subsequently the beginning of tree growth at the Gribben site.

Since the post-Algonquin high stages in the Michigan-Huron basins preceding the Sheguiandah, Korah, Stanley, and Chippewa and perhaps even the main Algonquin stage existed during this time of slow retreat from the Northern Peninsula (10,600 to 10,100 yr B.P.), it is possible that some of these entered the Superior basin, probably extending as far as its western end. Any evidence for this occurrence, such as shoreline features that may have formed along the margins of these lalces, however, was obliterated when the basin was reoccupied by the ice sheet during the Marquette Stadial. Without any direct evidence it is difficult to determine which of the higher stages first expanded through the Marquette and Huron Mountain areas, unti! it finally joined 'with a lalce in the western part of the basin. The nearest location where evidence can be found that links the position of the ice margin to Lake Algonquin is 25 km north of Sault Ste. Marie; Ontario. There, sandy and gravelly outwash channels that formed along the edge of the retreating Greatlalcean ice end in deltas at the main Algonquin leve!.

Whí!e the Greatlakean ice was retreating from the Lake Superior basin, recession of the ice margin 400 km east of Lalce Superior uncovered for the fírst time the lowest part of the North Bay outlet. This was the event which ended a series of post-Algonquin stages and initiated Lalces Stanley, Minong, and Chippewa in the Huron, Superior, and Michigan basins, respectively. These low-Ialce stages persisted throughout the remainder of the Gribben Interstadial.

Although the extent of glacial readvance during the Marquette Stadial is well documented in the 'Marquette area, little is known about the behavior of the ice sheet east of Lalce Superior. The ice margin must not have advanced far enough to have covered the North Bay outlet, however, because there is no evidence to indicate a return to high water levels in the Huron and Michigan basins during the Marquette

1 In 1976 and 1977 a forest of spruce trees that had been buried in outwash was uncovered 10 miles from Lake Superior near Marquette, Michigan. Carbon dates for five wood specimens ranged from 9,545 1: 225 yr B.P. to 10,230 ± 300 yr B.P., providing a mean of 9,925 yr B.P. The largest tree recovered from the excavation had at least 150 growth rings. The period of glacial retreat when growth of the Gribben fores! occurred has been narned the Gribben Interstadial. Tbe readvance that followed the Gribben Interstadial is referred to as the Marquette Stadial. Reforestation at the Gribben site probably did not begin until al least 150 to 200 years afier its deglaciation by Greatlakean ice (beginning of the Gribben Interstadial). Tbis gives a date for withdrawal of Greatlakean ice from the Marquette (and Huroo Mouotaio and Au Traio area) of sligbtly more than 10,100 yr B.P.

28

Stadial. Therefore, wilh Ihe exception of Lake Minong, which was displaced by glacial ice until it only occupied Whitefish Bay, Ihe low stages Stanley and Chippewa continued to exist unchanged except for a gradual rise of Ih.eir surfaces in response to isostatic rebounding of Iheir outlets.

Nine-Ihousand eight-hundred years ago Ihe last glacial event to affect Green Bay happened when, following a 17-km retreat oflhe ice margin from Ihe Marquette Stadial's terminal position, Ihe Au Train­Whitefish outlet was opened (Drexler et al., 1983). The drainage of several ancestral stages of Lake Superior Ihrough Ihat outlet and across Ihe floor of Green Bay to Ihe level of Lake Chippewa was responsible for Ihe cutting of a little-known but significant l<l\1dform -- The Au Train-Wbitefish-Green Bay Spillway.

REFERENCES CITED

Drexler, C. W., 1981, Outlet channels for Ihe post-Dululh lakes in Ihe Upper Peninsula of Michigan: Ph.D. dissertation, University of Michigan, Ann Arbor, Michigan, 285 p.

Drexler, C. W., Farrand, W. R., Hughes, J. D., 1983, Correlation of glacial lakes in Ihe Superior basin wilh eastward discharge events from Lake Agassiz, in Teller, J.T. and Clayton, Lee, eds., Glacial Lake Agassiz: Geological Ass'ociation of Canada Special Paper 26, p.261-290.

Foster, J. W. and Wbitney, J.D., 1850-51, Report on Ihe geology and topography of a portio n of Ihe Lake Superior land district in Ihe State of Michigan: U .S. Congress, House and Senate Executive Documents.

Futyma, R. P., 1981, The northern limits of glacial Lake Algonquin in upper Michigan: Quaternary Research, v. 15, p. 291-310.

Hough, J. L., 1958, Geology of Ihe Great Lakes: University of Illinois Press, Urbana, 313 p. Hughes, J. D., 1963, Physiography of a six quadrangle area in Ihe Keweenaw Peninsula nOrth of Portage

Lake: Ph.D. dissertation, Northwestern University, Evanston, Illinois, 228 p. __ , 1980, ThePleistocene Gribben Basin buried forest: Final project report, National Science

Foundation, Form 98A. . . . Leverett, F., 1929, Moraines and shorelines of Ihe Lake Superior region: U.S. Geological Survey

Professional Paper 154-A, 72 p. Russell, I. C., 1904, A geological reconnaissance along Ihe north shore of lakes Huron and Michigan:

Annual Report oflhe Michigan Geological Survey, p. 33-112. Saarnisto, M., 1974, The deglaciation history of Ihe Lake Superior region and its climatic implications:

Quaternary Research, v. 4, p. 316-339. Stanley, G. M., 1938, The submerged valley Ihrough Mackinac straits: Journal of Geology, v.46, p.

966-974. United States Department of Agriculture, 1977, Soil survey of Delta County and Hiawalha National

Forest of Alger and Schoolcraft Counties, Michigan, 139 p. WinchelI, N. A., 1871, The glacial features of Green Bay of Lake Michigan wilh sorne observations on

a probable former outlet ofLake Superior: American Journal of Science, v. 2, Ihird series, p. 15-19. Wold, R., 1970, Personal Cornmunications, University ofWisconsin-Milwaukee, January 1970.

Editor's Note: This paper is a slightly edited version of a paper published in Palmquist, J.C., ed., 1989, Wisconsin's Door Peninsula -- A Natural History: Perin Press, Appleton, WI,.p. 49-65.

29

GLACIAL ISOSTASY OF THE DOOR PENINSULA, WISCONSIN

James A. Clark and Todd A. Ehlers Department of Geology, Geography, and Environmental Studies'

Calvin College Grand Rapids, Michigan 49546

INTRODUCTION

The excellent shoreline deformation data collected long ago by Spencer (1871, 1888), Goldtbwait (1906, 1907, 1908, 1910), and Leverett and Taylor (1915) for tbe Great Lakes region haye been used by geophysicists for more tban 50 years to analyze eartb rheology and glacial isostasy (for example, Gutenberg, 1933; Broecker, 1966; Brotchie and Silvester, 1969; Walcott, 1970; Wolf, 1985). Therefore, as we review tbe classic field work of Goldtbwait on tbe Door Peninsula of Wisconsin, it is informative to consider also geophysical explanations of tbese same tilted shorelines.

The following topics are addressed in tbis brief paper: (1) tbe fit of model predictions to observed AIgonquin and Nipissing shorelines, (2) tbe existence of shorelines higher tban tbe main AIgonquin shoreline, (3) tbe rapid influx of water to tbe Lake Michigan basin from Lake Agassiz and its effect upon

tbe controlling outlets, and (4) tbe present rate of tilting on tbe Door Peninsula.

THEMODEL

Our numetical model assumes tbat tbe eartb is a layered" spherically syrnmetric viscoelastic and self-gravitating planet. Altbough more tban six rheological models have been used by us, tbe model tbat best explains tbe Great Lakes data is one in which fue mantle has a uniform viscosity structure (10" Pa-sec) and tbe litbosphere is elastic and 212 km tbick. The metbod, described in detail by Clark and otbers (1990), yields predictions of eartb deformation for any prescribed ice-sheet loading history. Here we use an ice sheet similar to tbose proposed by Boulton and otbers (1985) and Fisher and otbers (1985). Maximum ice thickness over tbe Great Lakes region in tbese models is very tbin (Iess tban 700 m). Our reconstructed ice sheet advances at 30,000 B.P., attaining its maximum configuration 18,000 years ago before retreating (Fig. 1).

Altbough earth deformation is predictedtbroughout tbe Great Lakes region, we report here on1y tbe results along a 160-km transect paralleling tbe Door Peninsula (Fig. 2).

RESULTS

As tbe Two Rivers ice retreated, tbe Calumet phase of glacial Lake Chicago filled tbe basin about 11,500 years ago (Hansel and otbers, 1985). Witb Chicago as tbe controlling outlet, predictions indicate tbat basin warping may have caused tbe resulting shorelines to be as high as 240 m (787 feet) at tbe northern tip of tbe Door Peninsula (Fig. 3). Lower shorelines are possible if eastward f10w across tbe northern part of Michigan's soutbern peninsula occurred. It is tberfore possible tbat shorelines higher tban tbe main Algonquin shoreline exist on tbe peninsula.

Larsen (1987) and Lewis and Anderson (1989) have surnmarized events relating to tbe formation of Lake AIgonquin in tbe Huron and Michigan basins. Predictions of outlet elevations during late Wisconsinan and postglacial times (Fig. 4) indicate tbat during AIgonquin time (11,000 to 10,000 B.P.)

31

o 3

Distance (km) . 1000 2000

---·30,000bp --- 18,000 bp - - - 12,000 bp ---- 7,OOObp

3000

Figure 1. Ice-sheet thickness at four times during Ihe glacial cycle. The profile is north-soulh and Ihe !hin soulhem ice-sheet region is from Boulton and others (1985) and Fisher and olhers. (1985).

Michigan

Michigan

Figure 2. Location of our 160-km transect along the Door Península.

32

I

00

00

00

00

Point Cornfort Sturgeon Bay Egg Harbor Death's Door Bluff , , I I ,

Ca/umet

¡ (P TI Huron Out/et) Algonqu n o --Goldthwait's Atgo;;'QU.2,t _ ---------_ .... Lake Michigan - - - -. -¡KÍrkfie/d Outlel) A/gonqUID

20 40 60 80 100 120 140

Distance Along Transect (km)

- -

r -r

r

260

240 ! 220 § ..... 200 ~

180 ~ 160

160

Figure 3. Predicted Calumet (11,500 D.P.) and Algonquin (10,700 U.P.) shorelines corupared with Goldthwait's (1907) Algonquin shoreline along Ihe transeet s110wn in Figure 2. 111a two predicted Algonquin shorelines represent differenees resnlting fram different Algonquin outlets ns suggested by Lewis and Anderson (1989).

lhe Port Huron outlet was always higher lhan lhe Kirkfield outlet, and so Kirkfield is predicted to be lhe controlling outlet of Lalce Algonquin. This result is in accord wilh observations (for example, Eschman and Karrow, 1985). But Lewis and Anderson (1989) cite evidence from Lalce Erie suggesting lhat Port Huron may also have occasionally shared control of lhe lalce leve!. This implies very high lalce levels caused by increaseddischargefrom Lalce Algonquin lhat may have resulted from early eastward drainage from Lalce Agassiz at about 11,000 RP. Lewis and Anderson suggest lhat lhe main Algonquin shoreline was formed due to possible catastrophic drainage of Lalce Agassiz at 10,700 B.P. Because of uncertainty in lhe controlling outlet for lhe main Algonquin, shoreline predictions are given for bolh lhe Kirkfield and Port Huron outlets (Fig. 3). The predicted outlet elevations differ, and so lhe predicted shorelines are displaced from each olher by 17 m (57 feet), and lhey bracket Goldlhwait's observations. If overflow from Port Huron did not attain lhe 184-m (605-foot) level (present sil! elevation is about 175 m), lhen lhe Port Huron predictions would be lower and even more in accord wilh observations.

Algonquin shorelines are not well dated in lhe Green Bay region despite lhe numerous shoreline features. At lhe soulhem end of Green Bay in lhe town of Howard (Fig. 2), we visited a site (182 m elevation) which Goldlhwait (1907, p. 95) claimed was an Algonquin beach. In fact, lhe feature was so prominent lhat he included a photograph of lhe beach in his book. We dug a pit through 107 cm (42 inches) of beach sand and found organics wilh wood lhat dated at 11,090 + 90 yr RP. (Bet3-22291). This organic layer was above a pebble lag and a red til!, and lhe date supports Goldlhwait' s shoreline interpretation.

Following lhe Chippewa low phase, slow tranSgression caused by uplift at lhe North Bay outlet reached lhe elevation of Port Huron and Chicago. At lhat time (ca. 5,000 B.P.) all three outlets were active and served as control s for Lalce Nipissing. The model predictions (Fig. 4) indicate lhat 5,000 years ago lhe elevations of lhese outlets were wilhin 2 m of each olher, explaining lheir simultaneous use. The predicted Nipissing shoreline is wilhin 1 m of Goldlhwait's observations (Fig. 5).

Bolh lalce-level gauges and model predictions indicate lhat lhe Door Peninsula is still dynamic and tilting up toward lhe north. Lalce-level gauges show lhat Sturgeon Bay is rising relative to Milwaukee

33

1200 • • • • • • , -, ., ,

--.. ét:: '-" 800 Z O E::: 400

~ O ~

~ ~

t .----- Chlcago , , . , ,

-PartRuron , ,

~ .... _._.- Klrkfleld : ,,·...-·-f-·_·_·_·. ..... - -NarthBay : ... " .... -.. -... ' --;. ~ ._'-. ... ..... : ... '. /

, , -=---~?,;~~ _____ ......... --~-...... r / , ,

1- '-..... .;, / , ...... /, , -.... . _._0 ._....... : ,

............ , , I , - , ,

"" /: , .. , -.... -- , , - - - , , , , , , , , , -• • . . • , .

300 --.. !

200 ~

100 E:::

~ O

-400 30 28 26 24 22 20 18 16 14 12 10 8

-100 64 2 O

1000 YEARS BP Figure 4. Predicted elevations of Ihe four outIets tha! controlled lake levels in Ihe Michigan basin. The Port Huron outIet was 17 m higher than Ihe Kirkfield at 10,700 B.P., so Ihe Kirkfield should have been Ihe controlling outIet at that time. However, increased inflow from Lake Agassiz could have raised lake level to the Port Huron elevation. At 5,000 B.P. Ih~ Chicago, Port Huron, and North Bay outIels were at nearly Ihe same elevation, so Ihey simultaneously could have controlled Ihe level of Lake Nipissing.

Poin! Comfort Sturgeon Bay Egg Harbor Dealh's Door B1uff ! 186.-----+----=-+---=---=-=--+--.::...:..::.~f.=-=:...,. 0.30

0.25 § 185 .~ ~

~ 184 \ss\"~ 0.20 @ _ 't1W -~- ....

- /ilc1eo> 0.15 ~ ~ 183 ~ Q,) ~ = 0.10 ~ == Go/dthwait's Nipissing .... ~ 1~ ~ ... 0.05 ~

~ ~~~~~~--~~--~-l .... 00 181 0.00 5 20 40 60 80 100 120 140 160 (IJ

Distance Along Transect (km) ~ Figure 5. Predict~ Ni?issing shoreline compared with Goldthwait's (1907) Nipissing shoreline .Iong Ihe transect shown m FIgure 2. The present predicted rate of tilting relative to the southem end of the transect is .lso shown.

34

I at arate of 1.2 mm!year. Because predictions underestimate this magnitude of tilting by almost 0.5 mm/year, it is likely that the predicted rate of tilting for the Door Peninsula (Fig. 5) is also an underestimate. It is of interest that this apparent tilting upward toward the north is not predicted to result from more rapid uplift 'at the tip of the Door Peninsula, but because the region is subsiding at a slower rate than that ofthe southern part ofthe transect. Relative to the center ofthe eartb, Death's Door Bluff is now subsiding at the rate of 3 mm/year, whereas farther south the subsidence rate is 3.25 mm/year. Predictions indicate that both of these regions rose following deglaciation until 6,000 B.P., when the uplift pattern changed to subsidence.

CONCLUSIONS

A very thin ice sheet is re.quired over the Great Lakes region to explain the ancient shorelines of the Door Peninsula and elsewhere. Models with a thicker ice sheet (for example, 2,000 m) over the region resulted in tilting that greatly exceeds observed deleveling. Predictions indicate that Calumet shorelines as much as 35 m higher than Algonquin shorelines may be present on the penirisula. AIgonquin predictions suggest that simultaneous use of the Kirkfield and Port Huron outlets during the main Algonquin phase was Iikely. This implies a considerable increase in discharge that was probably related to inflow from Lake Agassiz. The slightly tilted Nipissing shoreline is explained adequately by the model with all three outlets (North Bay, Port Huron, and Chicago) serving as controls. Finally, the region is still dynamic with apparent modern tilting upward toward the north caused by differential subsidence of the entire Door Peninsula.

REFERENCES CITED

Boulton, G. S., SIriith, G. D., Jones, A. S., and Newsome, J., 1985, Glacial geology and glaciology of the last mid-Iatitude ice sheets: Geological Society of London Journal, v. 142, p. 447-474.

Broeker, W. S., 1966, Glacial rebound and thedeformation ofthe shorelines ofproglaciallakes: Journal of Geophysical Research, V. 71, p. 4777-4783.

Brotchie, J. F., and Silvester, R., 1969, On crustal flexure: Journal of Geophysical Research, v. 74, p. 5240-5252.

Clark, J. A., Pranger, H. S. II, Walsh, 1. K., and Primus, J. A., 1990, A numerical model of glacial isostasy in the Lake Michigan basin, in Schneider, A. F., and Fraser, G. S., eds., Late Quaternary history of the Lake Michigan basin: Geological Society of America Special Paper 251, p. 111-123.

Coordinating Cornmittee on Great Lakes Basic HydrilUlic and Hydrologic Data, 1977, Apparimt vertical movement over the Great Lakes: U.S. Army Corps ofEngineers, Detroit, Michigan, 70 p.

Eschman, D.F., and Karrow, P. F., 1985, Huron basin glaciallakes; A review, in Karrow, P. F., and Calkin, P. E., eds., Quaternary evolution of the Great Lakes: Geological Association of Canada Special Paper 30, p. 79-93.

Fisher, D. A., Reeh, N., and Langley, 1985, Objective reconstructions of the late Wisconsinan Laurentide Ice Sheet and tbe significance of deformable beds: Geographie physique et Quaternaire, v. 39, p. 229-238.

Goldtbwait, J. W., 1906, Correlation of the raised beaches on tbe west side of Lake Michigan: Journal of Geology, V. 14, p. 411-424.

__ ' 1907, The abandoned shore-lines of eastem Wisconsin: Wisconsin Geological and Natural History Survey Bulletin 17, 134 p.

__ ' 1908, A reconstruction of water planes of tbe extinct glacial lakes in tbe Lake Michigan basin: Joumal of Geology, V. 16, p. 459-476.

_. __ ' 1910, Isobases of tbe AIgonquin and lroquois beaches and tbeir significance: Geological Society of America Bulletin, v. 21, p. 227-248.

Gutenberg, B., 1933, Tilting due to glacial melting: Journal of Geology, v. 41, p. 449-467.

35

Hansel, A. K.; Mickelson, D. M., Schneider, A. F., and Larsen, C. B., 1985, Late Wisconsinan and early Holocene history ofthe Lake Michigan basin, in Karrow, P. F., and Calkin, P. B., eds., Quaternary evolution of the Great Lakes: Geological Association of Canada Special Paper 30, p. 39-53.

Larsen, C. B., 1987, Geological history of glacial Lake AIgonquin and the upper Great Lakes: U.S. Geological Survey Bulletin 1801, 36 p.

Leverett, F., and Taylor, F. B., 1915, The Pleistocene oflndiana and Michigan and the history ofthe Great Lakes: U.S. Geological Survey Monograph 53,529 p.

Lewis, C. F. M., and Anderson, T. W., 1989, Oscillations of levels and cool phases of the Laurentian Great Lakes caused by inflows from glacial Lakes Agassiz and Barlow-Ojibway, Journal of Paleolimnology, v. 2, p. 99-146.

Spencer, J. W., 1888, Notes on the origin and history of the Great Lakes of North America: American Association for the Advancement of Science Proceedings, v. 37, p. 197-199.

__ ' 1891, Deformation of the AIgonquin beach and birth of Lake Huron: American Journal of Science, 3rd ser, v. 41, p. 12-21.

Walcott, R. l., 1970, Isostatic response to loading of the crust in Canada: Canadian Journal of Barth Sciences, v. 7, p. 716-727.

Wolf, D., 1985, An improved estimate of lithospheric thickness based on a reinterpretation of tilt data from Pleistocene Lake AIgonquin: Canadian Journal ofBarth Sciences, v. 22, p. 768-773.

36

TILL STRATIGRAPHY AND LATE GLACIAL SEQUENCE OF THE NORTHERN DOOR PENINSULA, WISCONSIN

AlIan F. Schneider Department of Geology

University of Wisconsin-Parkside Kenosha, Wisconsin 53141

"The Quaternary deposits of eastern Wisconsin are particularly interesting ... because the Green Bay Glacier, a well-defined unit among the glaciallobes which characterized the borders of the great North American ice sheets, traversed the eastern part of the State under topographic conditions which, while sufficiently marked to show the effects of topographic control on glacial flow, were yet of such comparatively small relief that the glacier deployed freely and with only moderate symmetry."

William C. Alden, 1918

TILL 5TRA TIGRAPHY

Introduction

Unconsolidated deposits of Quaternary age are generally thin throughout much of the northern Door Penin~ula. In Door County they range in thickness from O to 45 m (O to 150 feet), but only in a few areas are the deposits as much as 20 m (65 feet) thick (Sherrill, 1978). In general, the sedirnents are thicker along the Lake Michigan coast and thinner on the uplands and along the Niagara Escarpment adjacent to the Green Bay shoreline. The deposits are especially thin north of Sturgeon Bay, where bedroc\c iscommonly within 1 to 3 m (3 to 10 feet) of the surface. In rnany places, .unconsolidated deposits are absent entirely, both along the shorelines and on the interior upland, although usually only over relatively srnall areas. It has been reported that about 40 percent of the county has less than 1 rn (3 feet) of drift and soil aboye the bedrock. The deposits inelude tills, glaciofluvial sedirnents, shoreline deposits, dune sands, organic sediments, and sorne lacustrine sediments deposited in late-glacial and postglaciallakes.

Although the glacial deposits that blanket the bedrock in the northern Door Peninsula are generally thin, they do act as parent materials for virtually all soils of the area. About 75 percent of the soils in Door County are formed in glacial till (Link and others, 1978).

lt was previously thought that only two till units occur in the northern part ofthe peninsula (Thwaites and Bertrand, 1957; Schneider, 1981). It now appears that probably three and possibly four tills are present (Schneider, 1986, 1989, 1990a). At least three ofthese have been recognized farther south, but both of the more recently discovered units probably have a very limited distribution in the northern part ofthe peninsula. AII the units are late Wisconsinan. Pre-Wisconsinan deposits have not been recognized.

Liberty Grove Till

The oldest known till unit in the northern part of the Door Península is a coarse-grained yellowish-brown (lOYR 5/4) to brown (7.5YR 5/4) diamicton deposited by the Green Bay Lobe. It was first called the Liberty Grove till by Schneider (1981) and later formally named the Liberty Grove Mernber of the Horicon Forrnation (Mickelson and others, 1984). Mickelson and Syverson (in press) propose to restrict the name "Horicon" and to change its rank from formation to rnernber status; both the

37

Horicon and the Liberty Grove, in addition to other members originally inc1uded in the Horicon Formation, are considered to be members of the Holy Hill Formation.

The Liberty Grove is a pebbly loam till with a high carbonate content, largely dolomite, in all size fractions. As much as 70 percent of the combined silt and c1ay fractions is carbonate -- 55 percent dolomite and 15 percent calcite, as determined by Chittick analyses. The coarser fraction iS'dominated by pebbles and cobbles of Niagaran dolomite and, because of its coarse texture, the till commonly appears to be poorly sorted gravel upon casual examination of road-cut exposures. The matrix of the till (less than 2 mm), based upon analyses of 40 samples, has an average grain-size distributionof 50 percent sand, 39 percent silt, and 11 percent clay. The c1ay-mineral composition, based upon analyses of 38 samples, averages 17 percent expandables, 65 percent illite, and 18 percent kaolinite plus chlorite, as determined by H. D. Glass of the IlIinois State Geological Survey. The till commonly rests on a bedrock pavement and most of the material was c1early derived by eros ion of the local bedrock.

o I o

• , (

10

1p 1,5 Miles i

20 Kllometers

Explanatlon

D lacustrine areas

a RedTiII

• BuffTIII

... Locatlon of definlte or probable red till exposure

Figure 1. Map of Door County showing glacial deposits. (From Schneider, 1989, fig. 6; modified from Thwaites and Bertrand, 1957, pI. 8.) Lab analyses and reexamination of samples obtained from loeations shown by Ihe two solid lriangles in Ihe soulhem part of northem Door County (north of Sturgeon Bay) now suggest thal the sedimenls may be the pink sandy lill ralber Ihan Ihe red elayey till.

38

The Liberty Grove is the surticial till throughout virtually all of Door County north of Sturgeon Bay (Fig. 1) and takes its name from exposures in the Town of Liberty Grove at the north end of the peninsula. The till is relatively thin, ranging in thickness from O to 3 or 4 m (0-13 feet) throughout much of this area. It acts as the parent material for soils of the Ernmet and Omena series (Link and others, 1978). In all places where the base of the unit has been observed, it directly overlies Ordovician or Silurian bedrock. South of Sturgeon Bay it occurs at the surface in sorne areas, but in much of southern Door County it is buried by younger deposits of the Kewaunee Formation.

The Liberty Grove till is assigned to the late Woodfordian Substage of the Wisconsinan Stage of glaciation and is correlated with the Mapleview Member of the Horicon (Holy Hill) Formation on the west side of the Green Bay basin (Mickelson and others, 1984). South and east of Green Bay in Brown County the deposit is informally called the Wayside till (McCartney and Mickelson, 1984; Need, 1985). Thwaites and Bertrand (1957) assigned this till to the Cary substage, believing it to be the same till as that below the Two Creeks Forest Bed and equivalent in age to the gravellydrift of the Kettle Moraine. The pre-Twocreekan age ·must certainly be correct, but more recent investigations (for example, Evenson, 1973) indicate that it is not the same stratigraphic unit as that which underlies the forest bed at the Two Creeks type locality. .

Glenrnore Till

Overlying Liberty Grove till in sorne places is a fme-grained reddish-brown (5YR 4/4) till, whose Iithologic character contrasts sharply with that of the Liberty Grove. Not only is it much finer grained and completely different in color, but it contains considerably less carbonate, especially in the matrix. Whereas samples of Liberty Grove till nearly everywhere contain at least 50 percent, and cornmonly 65-70 percent, total carbonate in the combined silt and clayfractions, samples of the reddish-brown till typically contain between 30 and 40 percent total carbonate in the same size fractions. The dolornite/calcite ratio in the reddish-brown till is generally close to 1/1, whereas in the Liberty Grove the ratio is typically much greater -- as high as 3/1 or 4/1 in sorne samples.

This younger unit is one of the so-called red clayey tills of eastern Wisconsin(Fig. 2) that comprise the several members of the Kewaunee Formation (Mickelson and others, 1984). These tills were initially considered to be lacustrine deposits by Chamberlin (1877). Eighty years later they were referred to by Thwaites and Bertrand (1957) as the Valders till (Thwaites, 1943), a name that is still applied by many, incorrectly but understandably, to all fine-grained red tills of eastern Wisconsin. Tills of the Kewaunee Formation serve as parent material for soils of the Kewaunee series (Link and others, 1978).

GREEN SAY LOSE LAKE MICHIGAN LO BE

WEST SIOE EAST SIDE

MIDDLE INLET GLENMORE TWO RIVERS MEMBER MEMBER MEMBER

KEWAUNEE VALDERS MEMBER

KIRBY LAKE CHILTON

FORMATION MEMBER MEMBER HA VEN MEMSER

SIL VER CLlFF BRANCH RIVER MEMBER MEMSER OZAUKEE MEMBER

Figure 2. Red clayey till units of eastem Wisconsin. Not shown is the Florence Member, which occurs beneath the Silver Cliff Member on the west side of the Green Bay Lobe (Clayton, 1988). The Two Creeks Forest Bed, which accurs between .the Valders and Two Rivers Members in the Lake Michigan Lobe and between the Chilton and Glenmore Members in the Green Bay Lobe, is not recognized as a formal lithostratigraphic unit of the Kewaunee Formation by Mickelsan and others (1984).

39

The Kewaunee Formation inc1udes a number of fine-grained reddish-brown tm units (including the Valders) that have been differentiated on the basis of their area! distribution, stratigraphic position, lithologic characteristics, and stratigraphic relationship to the Two Creeks Forest Bed (Evenson, 1973; Mickelson and Evenson, 1975; McCartney and Mickelson, 1982; Acomb and others, 1982; Mickelson and others, 1984; Mode, 1989; Schneider, 1990b.) The reddish-brown tm ofDoor County is currently correlated as the Glenmore Member of the Kewaunee Formation (Schneider, 1986, 1989, 1990a). This unit was deposited by the Green Bay Lobe and is known lo overlie a Two Creeks-age forest bed just south of Green Bay (McCartney and Mickelson, 1982) that is radiocarbon dated at 11,980 ± 100 yr B.P. (ISGS480).

Designation of the red tm in Door County as Glenmore tm is somewhat tenuous. The interpretation that it was deposited by the Green Bay Lobe is based on a minimal number of tm-fabric analyses and on its areal distribution pattern, which is more consistent with a Green Bay Lobe deposit than a Lake Michigan Lobe deposit. The interpretation that it was deposited by the Green Bay Lobe in post-Twocreekan time (Le., during the Greatlakean Substage) is defended on the grounds that it appears to be continuous with Glenmore tm of Kewaunee and Brown Counties to the south.

Whereas Liberty Grove tm is the surface deposit north of Sturgeon Bay, red till covers most of the county south of Sturgeon Bay (Fig. 1), as well as in Kewaunee and Brown Counties (Need, 1985), where it is known to overlie Liberty Grove till in many places. Red till is virtually absent from northern Door County, having been observed at only a few scattered locations (Fig. 1), and in most of these places the identity of the deposit is suspect.

The Glenmore is particularly well exposed in low road cuts in the southwestern part of :boor County between Gardner Marsh (Au Grande Maret) and Sugar Creek. It has also been well exposed south-southeast of Sturgeon Bay, particularly along Clay Banks Road (County Highway U). For example, approximately 6 m (20 feet) of the till, sharply overlying' 3 m (9-10 feet) of lacustrine sand and beach deposits, has been exposed for the past several years in a large pit on the west side of Clay Banks Road. Several years ago D. M. Mickelson observed shallow grooves oriented NW-SE at the base of the till at this site, which is consistent with the interpretation that the unit was deposited by the Green Bay Lobe. This interpretation is also strongly supported by two till-fabric analyses made by Ardith Hansel and the author in 1991 (Fig. 11 in road log).

Other Tills

Also overlying Liberty Grove till is a recently discovered pink sandy till, whose distribution appears to be limited to an area north and east of Sturgeon Bay. Although this pink sandy till and red c1ayey Glenmore till are both known to rest on yellowish-brown Liberty Grove till, they have not been found in stratigraphic contact with each other. Thus, the age relation of the pink tm to the Glenmore is unknown. Therefore, it is also not known whether the pink till was laid down by a different ice advance than that which deposited the Glenmore tm or whether it is a sandy facies of the Glenmore. Perhaps it is the result of the assimilation of Liberty Grove till in the Glenmore.

The best exposure of the pink sandy tm was found in the Kiehnau dolomite quarry on Mathey Road, about a mile north of Wisconsin Highway 57. An excellent section was visible here in the early 1980s; it exposed 3.5 m (5 feet) of pink sandy till overlying 1 m (3 feet) of Liberty Grove till resting on a beautifully polished and striated bedrock pavement. Unfortunately, this exposure was destroyed several years ago. lt certainly was one of the best exposures, probably the best exposure, of Ipultiple tills ever seen in Door County.

40

It has been suggested by sorne that this pink till may be, or may be equivalent to, the Branch River Member of the Kewaunee Formation (Fig. 2). The Branch River is the surface till southwest ofDenmark in southeastern Brown County and the northwestern comer of Manitowoc County (McCartney and Mickelson, 1982; Need, 1985). It is a1so present at the surface in northeastern Brown County (Need, 1985), not far from the southwestern comer of Door County. The Branch River till is believed to have been deposited by ice of the Green Bay Lobe. It is younger than the Horicon Member of the Holy HiII Formation and older than the Glenmore Member of the Kewaunee Formation (McCartney and Mickelsori, 1982; Mickelson and others, 1984).

A possible fourth till unit occurs a10ng the Lake Michigan shoreline in extreme southeastern Door County, just south of Robert LaSalle County Park. Several years ago two fine-grained red-till layers separated by 1-3 m (3-10 feet) of sand were observed near the north end of a 21 10 24 m (7010 80 foot) bluff. The upper layer, about 2.5 m (8 feet) ofwhich was exposed at the top ofthe bluff, was interpreted as Glenmore tUI. The same stratigraphy has not been observed on subsequent visits to the site, however. If two depositional till units are indeed present and the upper unit is correctly identified as Glenmore, it is still unknown whether the lower till is pre-Twocreekan or post,Twocreekan in age and whether it was deposited by the Lake Michigan Lobe or by the Green Bay Lobe. Possibly it is part of the Valders, the Haven, or the Two Rivers Member of the Kewaunee Formation (Fig. 3). AH three of these units were deposited by the Lake Michigan Lobe; the Valders and-Haven tills are pre-Twocreekan, the Two Rivers till is post-Twocreekan, as it overlies the Two Creeks Forest Bed (Evenson, 1973) and contains wood derived from the Two Creeks Forest Bed (Black, 1970; Schneider, 1990b).

'¡2"N 430tN ,,4°N 46'N

SOUTH ENO CHICAGO MlLWAUKEE L MICHIGAN

TWQ CREEKS MACKINAW CITr

"

12

OAK CREEK FORMATION

Figure 3. Time-distance diagram fOf the Lake Michigan bnsin. Vertical scale represents lime in Ihollsands of radiocarbon years B.P., and the horizontal seale represenls Ihe approximate distance along Ihe north-sollth flowline of fue Lake Michigan Lobe. Formal names of lithostratigraphie units in eastem Wiscollsinare given at the right side of the figure. (From Mode, 1989, fig. 4; modified from Evenson and others, 1976, fig. 2).

41

In an attempt to distinguish between or among the red till units, the cIay mineralogy of nearly 100 samples of red till collected by the author was determined by Herb Glass of the Illinois State Geological Survey. Glass has contended that the red tills can be differentiated on the relative percentages of illite. (See, for example, Glass, 1981.) More than 60 samples carne from sites in the southern Door Peninsula. Unfortunately, no consistent cIay-mineral pattern has emerged for the red tills of this area, except for the fairly narrow range of expandable minerals (30-38 percent) in the Glenmore till ofthe Denmark Moraine, its probable continuation on the east side of Green Bay in Brown and Kewaunee COUlities, and in the interior ofthe peninsula in Kewaunee County. Farther north in Door County, however, this consistency deteriorates. The clay-mineral composition of red till in the Two Rivers Moraine and its northward continuation is variable and has several anomalies. Quite possibly, these anomalies reflect the incorporation and mixing of different tills. The results of Glass' analyses continue to be studied, however, in an attempt to find sorne significant pattern in the relative abundance of the cIay minerals.

GLACIAL HISTORY

Virtually nothing is known about the glacial history of the northern Door Peninsula for over 99 percent of Pleistocene time. Based upon evidence from other parts of the state and the upper Great Lakes region; the area was probably glaciated many times during the Pleistocene Epoch, but there is no direct evidenee to support this assumption. In faet, there is concIusive evidence for only two ice advances in Door County, both during late Wisconsinan time between about 17,000 and 11,500 years ago.

The oldest positive evidence bearing on the glacial history of the area is the presence of Liberty Grove till (Schneider, 1981, 1986, 1989, 1990a). Liberty Grove till and deposits of equivalent age are the oldest glacial sediments throughout the Door Peninsula, as well as in other areas farther south in eastern Wisconsin. Where present in Door County, it directly overlies Ordovician or Silurian bedrock in all· places where the base of the till has been observed.

The Liberty Grove till is assigned to the late Woodfordian (Cary) Substage of the Wisconsinan Stage of glaciation. Jt was probably deposited about 16,000-17,000 years ago, but no radiocarbon dates are available to verify this date.

Liberty Grove till rests directly on a polished and striated bedrock pavement throughout much of .. Door County, and it is probable that the dolomite was abraded and striated during the same ice advance

as that which deposited the tnl. Moving generally southward, the ice carne out of the Green Bay basin, overtopped the Niagara Escarpment, and flowed obliquely across the peninsula to the Lake Michigan basin. Just prior to general glaciation of the upland, thin tongues of ice (in effect, small valley glaciers) may have crossed the peninsula from northwest to southeast, filling and seouring the joint-controlled bedrock lowlands and temporarily segmenting the county into a string of nunataks. Possibly the bedrock valleys had been enlarged by previous glaciations, thus providing ready avenues of entry through the escarpment, but there. is Iikewise no direct evidence for this.

The movement of the Green Bay Lobe across the upland was somewhat east of south. Hundreds of sets of striae, especially north of Sturgeon Bay, attest to flow direction. DrumIins, such as those near

-the north end ofthe peninsula in the Town ofLiberty Grave (Fig. 5 in road lag), and those just southwest of Sturgeon Bay (Fig. 10 in paper by Schneider elsewhere in this guidebook), indicate the same general flow pattern as the striations. In the northern part of Door County, the flow was S. 5-15° E., whereas in the Sturgeon Bay area and farther south the direction was S. 15-25° E. The flow pattern shown on Alden's 1903 map of eastern Wisconsin (Fig. 4) is remarkably accurate for the Door Peninsula.

42

I I

LO

o 10 20 30 40. 50 Miles

Figure 4. Map of eastem Wisconsin showing ice-tlow pattems of the Green Bay and Lake Michigan Lobes during the late Wisconsinan. (From Martin, 1916, fig. 79; modified from Alden, 1904, pI. 1.)

43

In their account of the Pleistocene geology of the Door Peninsula, Thwaites and Bertrand (1957, p. 850) observed that "the Cary ice movements do not indicate the marked division into two lobes which is manifest farther south." There is indeed no evidence whatever to suggest that ice from the Lake Michigan basin covered any part of Door County during the Woodfordian Substage. Perhaps the southern part of the Laurentide Ice Sheet was not lobate at this time (unlikely), or perhaps the Lake Michigan Lobe did not radiate and thus was confined to the deeper part of the lake basin (also unlikely). Possibly it was excluded from the upland by the earlier presence of Green Bay Lobe ice (more likely). The latter probably crossed the area with relative ease, having had the advantage of flowing generally downdip toward the lake basin, and possibly it covered the entire county before the western margin of the Lake Michigan Lobe reached the edge of the much deeper basin through which it was moving.

The later ice movement, in my interpretation, occurred during the post-Two Creeks Greatlakean Substage, about 11,500 years ago. Once again, the ice apparently carne out of the Green Bay basin. This time it left a fine-grained reddish till called the Glenmore till (McCartney and Mickelson, 1982).

The general absence of red tm in northern Door County (Fig.l) was noted by Thwaites and Bertrand, who stated that "the scarcity of red tm in Door County north of Sturgeon J3ay and in considerable parts of counties to the south has long been a puzzle. The hypothesis that these areas were nunataks is disproved by their elevations and by the presence of local isolated patches of red till within the areas" (Thwaites and Bertrand, 1957, p. 865). I concur with these authors that the ice was thin but, contrary to their opinion, I suggest that much of northern Door County probably was a nunatak -- or possibly a string of nunataks separated by linear ice streams, much as it may have been during the early part of the Woodfordian (Cary) advance. Fingers ofthe Green Bay Lobe may have entered sorne of the bedrock lowlands, possibly filling the valleys and spilling over onto the upland surface in a few places. Because of its thinness, however, and the presence of the high west-facing Niagara Escarpment, the ice apparently did not overtop the eastern rim of the Green Bay basin and cross the upland as a continuous ice sheet north of Sturgeon Bay. 1 suggest that the ice in the basin, assuming that it was groundect, was probably no more than 50 or 60 m (160 or 200 feet) thick.

Farther south, the head of Sturgeon Bay is 2-112 km wide and provided the ice with an easy access route through the Sturgeon Bay lowland to the Lake Michigan basin. Southwest of Sturgeon Bay the Niagara Escarpment is more dissected and is broken into two lower escarpments, the eastern of which is commonly several miles inland from the Green Bay shoreline (see Sherrm, 1978, pl.l); dolomite bluffs, therefore, are either absent or relatively low. In addition, the Green Bay basin is 15 to 25 m (50-80 feet) shallower; assuming that the thickness of the ice was comparable to that farther north, the

. glacier would have been higher relative to the land than farther north. Thus the ice could readily have encroached upon the peninsula, overtopping the crests of the two low cuestas and flowing between bedrock outliers, and moved downdip toward the Lake Michigan side of the peninsula with relative ease.

Parts of Door County may have been glaciated on two other occasions during the late Wisconsinan, as suggested by the possible presence of two additional tms. At this time, however, the evidence for both these advances is sparsé and inconclusive.

The Glenmore and Two Rivers tills are considered to be time equivalent (McCartney and Mickelson, 1982; Mickelson and others, 1984). If two till units are actually present at LaSalle Park and the lower till is indeed Two Rivers till and if the red clayey till that covers most of southern Door County is indeed Glenmore, then the Lake Michigan Lobe must have reached the eastern shore.in the southernpart of the peninsula shortly before the Green Bay Lobe. Such a relationship was inferred by Heiny (unpub.), who identified Glenmore till aboye Two Rivers till in the Lake Michigan bluff on the north side of Kewaunee. South of Kewaunee, however, Glenmore till appears to be below Two Rivers till (Acomb and others, 1982; Heiny, unpub.). Clearly, additional investigation is necessary.

44

REFERENCES CITED

Acomb, L. J., Mickelson, D. M., and Evenson, E. B., 1982, TiIl stratigraphy and late glacial events in the Lake Michigan Lobe of eastern Wisconsin: Geological Society of America Bulletin, v. 93, p.289-296.

Alden, W. C., 1904, The Delavan Lobe of the Lake Michigan glacier of the Wisconsin stage of glaciation: U.S. Geological SurveyProfessional.Paper 34,106 p.

__ ' 1918, The Quaternary geology of southeastern Wisconsin: U.S. Geological Survey Professional Paper 106, 356 p.

Black, R. F., 1970, Glacial geology ofthe Two Creeks forest bed, Valderan type locality, and northern Kettle Moraine State Forest: Wisconsin Geological and Natural History Survey Information Circular No. 13, 40 p.

Chamberlin, T. C., 1877, Geology of eastern Wisconsin, in Geology of Wisconsin, v. 2, p. 91-405. Clayton, Lee, 1988, Florence Member of the Kewaunee Formation, in Attig, J. W., Clayton, L., and

Mickelson, D. M., eds., Pleistocene stratigraphic units of Wisconsin, 1984-1987: Wisconsin Geological and Natural History Survey Information Circular 62, p. 57-59.

Evenson, E. B., 1973, Late Pleistocene shorelines and stratigraphic relations in the Lake Michigan basin: Geological Society of America BulIetin, v. 84, p. 2281-2298.

Evenson, E. B., Farrand, W. R., ESchman, D. F., Mickelson, D. M., and Maher, L. J., 1976, GreatIakean Substage; A replacement for Valderan Substage in the Lake Michigan basin: Quaternary Research, v. 6, p. 411-424.

Glass, H. D., 1981, Clay mineral stratigraphy of the Pleistocene tills of Lake Michigan: Journal of GeoIogical Education, v. 29, p. 204-205.

Heiny, J. S., unpub., Glacigenic sediment facies associations along the western shore of Lake Michigan near Kewaunee, Wisconsin.

Link, E. G., Elmer, S. L., and Vanderveen, S. A., 1978, Soil Survey ofDoor County, Wisconsin: U.S. Department of Agriculture, Soil Conservation Service, 132 p~

Martin, Lawrence, 1916, The physical geography of Wisconsin: Wisconsin Geological and Natural History Survey BulIetin 36, 608 p. (Second edition published in 1932, third edition in 1965.)

McCartney, M. C., and Mickelson, D. M., 1982, Late Woodfordian and Greatlakean history of the Green Bay Lobe, Wisconsin: Geological Society of America BulIetin, v. 93, p. 297-302.

Mickelson, D. M., and Evenson, E. B., 1975, Pre-Twocreekan age ofthe type Valders till, Wisconsin: Geology, v. 3, p. 587-590.

Mickelson, D. M., Clayton, Lee, Baker, R. W., Mode, W. N., and Schneider, A. F., 1984, Pleistocene stratigraphic units of Wisconsin: Wisconsin Geological and Natural History Survey MiscelIaneous Paper 84-1, 97 p.

Mickelson, D. M., and S~erson, K. M., in press, Pleistocene geology of Ozaukee and Washington Counties, Wisconsin: Wisconsin Geological and Natural History Survey Information Circular.

Mode, W. N., 1989, Glacial geology of east-central Wisconsin, in Palmquist, J. C., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 66-81.

Need, E. A., 1985, Pleistocene geology of Brown County, Wisconsin: Wisconsin Geological and Natural History Survey Information Circular 48, 18 p.

Schneider, A. F., 1981, Late Wisconsinan glaciation ofDoor County, Wisconsin: Geological Society of America Abstracts with Programs, v. 13, p. 316.

__ o _' 1986, TiIl stratigraphy ofthe northern Door Peninsula, Wisconsin: Geological Society of America Abstracts with Programs, v. 18, p. 322-323.

__ ' 1989, Geomorphologyand Quaternary geology ofWisconsin's Door Peninsula, in Palmquist, 1. C., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 32-48.

__ ' 1990a, Door County's Glacial Heritage; A foundation for the future, in HershbelI, K.E.,ed., Door County and the Niagara EScarpment; Foundations for the future: Wisconsin Academy of Sciences, Arts and Letters Conference Proceedings, October 1989, p. 15-35.

45

__ ' 1990b, Radiocarbon confirmation of tbe Greatlakean age of tbe type Two Rivers till of eastern Wisconsin, in Schneider, A. F., and Fraser, G. S., eds., Late Quaternary history of tbe Lake Michigan basin: Geological Society of America Special Paper 251, p. 51-55.

Sherrill, M. G., 1978, Geology and ground water in Door County, Wisconsin, witb emphasis on contarnination potential in tbe Silurian dolomite: U. S. Geological Survey Water-Supply Paper 2047,38 p.

Thwaites, F. T., 1943, Pleistocene of part of northeastern Wisconsin: Geological Society of America Bulletin, v. 54, p. 87-144.

Thwaites, F. T., and Bertrand, Kennetb, 1957, Pleistocene geology oftbe Door Peninsula, Wisconsin: Geological Society of America Bulletin, v. 68, p. 831-880.

46

GLACIATION AND KARST FEATURES OF THE DOOR PENINSULA, WISCONSIN

Ronald D. Stieglitz Department of Natural and Applied Sciences

University of Wisconsin-Green Bay Green Bay, Wisconsin 54311

William E. Schuster Door County Soil and Water Conservation Department

Sturgeon Bay, Wisconsin 54235

INTRODUCTION

The Door Peninsula of Wisconsin is part of the most prominent of a series of cuestas formed by the eastward dip of marine sedimentary rocks away from the Wisconsin Dome. The capping Silurian dolos tones are comparatively resistant to mechanical eros ion and helped to split the Pleistocen,e glaciers into lobes. One of these lobes advanced through what was probably a preglacial lowland developed on softer rocks to the west and. further increased the topographic relief between the bay of Green Bay and the peninsula. To the east, another lobe expanded into what is now the Lake Michigan basin on the dip slope ofthe cuesta. Following the final withdrawal of the last ice, the peninsula was affected by the waters of several postglacial lakes. Shoreline features of both wave-cut and wave-built origin indicate the extent of inundation.

The dolostones of the península are also modified by fracturing and ground-water dissolution. A wide variety of karst features have been mapped in the northern part of the area (Johnson and Stieglitz, 1990). The actual age of the karstificatión is opento question, although sOrne features appear to both pre-date and post-date the most recent glaciation. As of noW, no dates have been obtained from speleoliths or cave decorations, and radiocarbon dates of organic materials from fill in the Brussels HiII cave in the southern part of Door County are too young to indicate much about the cave origino A better understanding of the karstification and its relationship to glaciation is of considerable significance to water quality and land-use issues in the area.

BEDROCK GEOLOGY

. The geology of the peninsula has been described by Sherrill, (1978), Kluessendorf and Mikulic (1989), and Stieglitz (1990) and will be only briefly reviewed here. A generalized stratigraphic colurnn is presented in Figure 1.

A sequence of limestones, dolostones, and shales of the late Ordovician Maquoketa Formation are the oldest rocks found on the peninsula. The distinctive bluish or greenish colored rocks are abundantly fossiliferous in places and resemble rocks of similar age in the vicinity of Cincinriati, Ohio. Where uncapped by younger dolostones, the formation probably was easily excavated by the glaciers. The low permeability of the formation serves to separate the upper aquifer system of the Silurian rocks and glacial deposits from the deeper confined aquifer and effective1y restricts water circulation and karst developrnent to the overlying forrnations.

The iron-containing Neda Formation is known frorn outcrops in southern Door and Brown Counties and frorn well logs in Manitowoc County. The unit is usually considered to be of late Ordovician age, although sorne doubts persist (Ostrom, 1967). The Neda has an irregular distribution and appears to pinch out or to be replaced to the north.

47

GENERAL STRATIGRAPHY NORTHERN DOOR COUNTY, WISCONSIN

Chranoslratagraphic UnUs Lllhoslratagraphle Unlls

~yslem Serie; Slage Group Formalion Member Thlekness Lllhology Range

N,~, Eur, Eur,

;i '<~' . :', :.;:,:::

" Horleon I 0-90 1~/~-:.~w8t\. c:s / 7'/ ~

" " I 7 / 7 .!! :S ~,

Engadlna / / / / " 0-100 u " " 3 ;: e .. ;; / 7 //7 3 ~

'" ~c Cordetl 30-90 - .

" ¡!~

I!

I Manlstlque ~

~ ~

Z SchooleraH 0-60 e . ~ 'C

" " i;¡ ~

e 'ji Hendrlcks 25-80 ~ Ji! 'C BurolBluff g¡ " Byron. 11G-130 ~ -" ~

-- :::l

e " ~ ~ 'E 'C ... • Mayvllie 230 "

~ ~ ... H " .. ~ .. a:

? Neda ?

-L- =-5~-' f-! '-- .. - - }:

" " -a ~ Maquokela 400 - - --=--~4 ;: 'c, .,---" ~ 'l! ,:¡¡ O

=-~--===-~ Figure 1, Straligraphic column of norlhem Door County,

48

To the casual observer, the rocks that make up the Silurian formations appear to be a sequence of very similarly appearing dense buff to light-gray dolostones. In reaIity, the units have distinctive differences oftexture, bedding, porosity, and jointing that influence resistance to mechanical and chemical weathering and ground-water dynamics. The following five formations, in ascending order, have been recognized on the peninsula: Mayville Dolomite, Byron Dolomite, Hendricks Dolomite, Manistique Formation, and Engadine Dolomite.

The Mayville Dolomite consists of buff, rather rough-weathering porous-appearing dolostone. This formation is a prime aquifer for the area (Sherrill, 1978). The overlying Byron Dolomite is a sequence of predominantly light-gray smooth-weathering dense laminated dolostones. The rocks are poorly fossiliferous and reflect deposition in very shallow water to emergent conditions. The superjacent Hendricks Dolomite seems to be a transitional unit between the Byron and the overlying units. Dense laminated layers are interbedded with coarser textured fossil-containing lithologies which seem to reflect alternating conditions and less restricted environments upward. The Hendricks Dolomite thins to the south, and the stratigraphic relationships and correlations of the rocks aboye the Byron with Silurian units in southern Wisconsin become less c1ear as the rocks are traced into Kewaunee and Manitowoc Counties. The overlying gray thin-bedded richly fossiliferous and chert-containing rocks are placed in the Manistique Formation. The youngest rocks on the peninsula, gray medium-crystalline, thick but wavy­bedded dolostones, are placed in the Engadine Dolomite. Outcrops of this unit are restricted to the eastern side of the area.

KARST FEATURES AND GLACIATION

The type and density of the karst features in northern Door County have been described in sorne detail by Johnson (1987) and Johnson and Stieglitz (1990). They also mapped the distribution and orientation of ·sinkholes and fractures, as well as attempting to evaluate the relationships betwéen karstification and other factors. Rosen (1984) and Rosen and others (1987) studied several areas on the p.eninsula and described it as glaciokarstic. Schneider (1990) discussed the glacial history of' the peninsula.

There has been considerable interest in the effects of glaciation ofkarst areas (Ford, 1983, 1987). Schroeder and others (1986) reported ice-push caves in the Montreal area, and Hedges (1972) and Stieglitz and others (1980) commented on possible periglacial phenomena along the face of the Niagara Escarpment in Iowa and Wisconsln, respectively. Striations, glacial polish, drift-filled karst features, and widespread karren on exposed rock surfaces testify to the relationships in eastern Wisconsin. Three geomorphic features are of special interest on the peninsula -- bedrock steps or schichttreppen, dolomite pavements, and abandoned stream channels.

Stepped bedrock surfaces or schichttreppen are common throughout the area. Rosen (1984) studied sorne prominent examples in southern Door County associated with the upland near the village of Brussels. Steps are found on the sides of bedrock highs flanking the northwest-southeast-trending valleys that dissect the peninsula. In many places, soil depth increases from only a few centimeters to more than a meter over very short horizontal distances. Where the steps are unmantled and the bedrock riser is exposed, the upper surface or tread often exhibits a rather dense suite of small to medium karst features. The apparent greater amount of dissolution can be explained by an increased flow ofwater over and through the rock toward the step face and the lack of a protecting covering of calcium-containing soil. The effectiveness of the drift soils to neutralize infiltrating water is evidenced by exposures of unaltered striations and excellent glacial polish in shallow excavations.

Sorne of the stepped surfaces are extensive and form dolomite pavements or kamenitzas. Other large pavements are located on broad flat areas not associated with obviously stepped terrain. An easily

49

accessible example can be observed along Mathey Road on the east edge of Section 10, T. 27 N., R. 26 E. on the Sturgeon Bay East 7.5-minute quadrangle. Sorne of the pavements are found on the higher parts of the topography, such as that in the SE1I4 Section 23, T. 30 N., R. 27 E., Baileys Harbor 7.5-minute quadrangle, whereas others occur in low positions on the eastern dip slope of the cuesta -- for example, SE1I4 Section 25, T. 28 N., R. 26 E., Sturgeon Bay East 7.5-minute quadrangle. Pavement surfaces are usually separated into blocks by widened joints or grikes and show other evidence of dissolution. It is also interesting to note that at sorne locations the upper meter or so of the rock has been extensively modified to form a porous epikarst zone that would not appear capable of resisting any significant glacial erosiono An example of such a pavement that has been disturbed by recent excavation occurs on the west side of Wisconsin Highway 42/57 in the SE1I4 Section 21, T. 27 N., R. 25 E., Sturgeon Bay West 7.S-minute quadrangle. This raises the question of whether the presence of this feature indicates that considerable dissolution has occurred in postglacial time or rather that those locations have escaped glacial scouring. These interesting landforms have been studied by Williams (1966) and Rose and Vincent (1986), among others.

Several examples of abandoned stream channels occur on the peninsula. One is located along County Highway M in Sections 3 and 4, T. 27 N., R. 25 E. on the Sturgeon Bay West 7.S-minute quadrangle. (This site is one of the stops on the field trip.) Discharge from the drainage basin is primarily through a spring complex developed in the face ofthe escarpment, which is not very prominent at this point. The channel does carry water over the scarp during the snow-melt season of most years. At those times, the stream insurges and resurges at several places along its course and becomes a disappearing stream as the water level in the bedrock declines.

Another excellent example can be found farther north in Egg Harbor Township in the SW1I4 Section 10, T. 29 N., R. 26 E. on the Egg Harbor 7.S-minute quadrangle. There the channel can be traced toward the escarpment face across a series of bedrock steps that apparently were small cataracts in the stream. At present, the channel remains totally dry and does not carry water at any time of the . year. Water does discharge from small springs and seeps at the base of the escarpIÍlent slightly aboye the level of Green Bay. The channel is found in an area with no surface drainage that Johnson and Stieglitz (1990) identify as their Holokarst A Zone and based on orientation and extent, it seems to have drained a rather broad shallow basin to the east. When and how the feature was formed and the timing and reasons for its abandonment are uncertain.

Tecumseh'Cave is located in the NE1I4SW1I4 Section 3, T. 29 N., R. 26 E. on the Egg Harbor 7.5-minute quadrangle about 1.5 km to the north. This cave is quite long with over 3,000 m of explored passages and forms part of an extensive subsurface system that probably drains the land for a considerable distance to the east of the escarpment. At least two relationships may exist between the abandoned channel and the cave system. It is possible that the channel predates the formation of the cave or at least the effective integration of the larger system. In that case, the channel would have been abandoned as the subsurface drainage became more efficient and capturedsurface runoff. On the other hand, it is also possible that the channel was cut during a much shorter and more recent time when the subsurface drainage was blocked with glacial drifi of low permeability. The karst interface features may then have reopened and enlarged in postglacial time to once again direct the surface drainage into the older

. subsurface conduit system.

ENVIRONMENT AL IMPLICATIONS

In Door County, as in other regions of karst geology, the activities of humans ofien have a direct impact on the quality of the underlying drinking-water aquifer. Enlargedcrevices and fractures, sinkholes, and other karst features provide direct unattenuated routes for surface runoff waters to enter the aquifer. The surface runoff can contain contaminants related to land use in the contributing

50

watershed. Municipal and private water-supply wells eontaminated during lhe spring snow-melt season or by olher aquifer reeharge events are indieative of lhe direet surfaee to subsurfaee conneetions present in karst areas.

Door County differs from many karst regions by lhe large areas of shallow soil cover overlying lhe solution-altered bedroek. The Door County Soil Survey (Link and olhers, 1978) indieates lhat approximately 22 pereent of lhe land area of lhe county has soils lhat are 0.5 m or 1ess to bedroek. Furthermore, an additional 17 pereent of lhe land area has soils lhat are between 0.5 and 1 m lhiek. Considering lhe important role lhat soils perform in lhe attenuation of contaminants in surfaee water as it moves downward to lhe ground-water aquifer, lhe greater suseeptibility of Door County's drinking­water supply to surfaee-derived pollution is apparent. Hallberg and Hoyer (1982) in lheir studies of ground-water quality in northeastern Iowa, an area of karst features, noted lhat eontamination is eontrolled by lhe deplh of lhe soil material overlying lhe bedroek. They defined lhin soils as those less lhan 15 m lhick and very lhin soils as lhose less lhan 7.5 m to bedrock, and noted an inereased occurrence of ground-water contamination in areas of very lhin soils. In Door County, approximately 39 percent of lhe land area is mapped as less lhan 1 m to bedroek, and field investigations indieate lhat lhis is a conservative figure.

The ground-water quality of northern Door County is described by Bachhuber and Schuster (1987) in lhe Nonpoint Source Control Plan for lhe Upper Door Priority Watershed Projeet. Modern and historical records of ground-water contamination by bacteria, nitrates, lead, arsenic, olher toxic metals, organic pesticides, and volatile organic compounds are all well documented in lhe watershed plan. Pollution sources such as barnyards and environmental features such as soils and sinkholes were mapped and inventoried for lhe Northern Door Watershed Project. That information was used to develop pollution-potential maps and to allocate state cost-share funds to landowners for installation of pollution­abatement practices. Additional ground-water monitoring projects have been carried out to better understand flow systems, determine water quality, and to asses.s lhe effectiveness of beSt management pracHces. A second priority watershed project will begin early in 1993 and focus on lhe area lhat drains to Green Bay along lhe western side of lhe county from Sturgeón Bay soulh to Brown County.

Local and state governmental agencies continue to cooperate on projects and programs designed to understand and protect lhe natural environment. Many of lhe land-use problems result from lhe glaciation and karstification of lhe region. Door County has been very active in its efforts to regulate septic systems and land spreading of liquid organic wastes. On lhe olher hand, more detailed information is needed about lhe physical aspects of lhe drift and bedrock formations. To lhat end, a project to describe and characterize lhe fracture systems in lhe dolos tone units is underway. Bolh political and scientific efforts of lhese types must continue in order to ensure environmental quality.

51

REFERENCES CITED

Bachhuber, J., and Schuster, W. E., 1987, Nonpoint source control plan for tbe Upper Door Priority Watershed Project: Wisconsin Department of Natural Resources, Madison, Wisconsin.

Ford, D. C., 1983, Effects of glaciation upon karst aquifers in Canada: Journal of Hydrology, v. 61, p. 149-158.

, 1987, Effects of glaciation and permafrost upon tbe development of karst in Canada: Eartb -- Surface Process and Landforms, v. 12, p. 507-521. Hallberg, G. R., and Hoyer, B. E., 1982, Sinkholes, hydrogeology, and ground-water quality in

northeast Iowa: Iowa Geological Survey Open File Report 82-3, 118 p. Johnson, S. B., 1987, The karst of northern Door County, Wisconsin: unpublished M.S. Thesis,

University of Wisconsin-Green Bay, 122 p. Johnson, S. B. and Stieglitz, R. D., 1990, Karst features of a glaciated dolomite peninsula, Door County,

Wisconsin: Geomorphology, v. 4, p. 437-454. Kluessendorf, J., and Mikulic, D. G., 1989, Bedrock geology of tbe Door Peninsula of Wisconsin, in

Palmquist, J. C., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 12-31. .

Link, E. G., Elmer, S. L., and Vanderveen, S. A., 1978, Soil Survey of Door County, Wisconsin: U. S. Department of Agriculture, Soil Conservation Service, 132 p.

Mode, W. N., 1989, Glacial geology of east-central Wisconsin, in Palmquist, J. C., ed., Wisconsin's Door Peninsula: Perin Press, Appleton, Wisconsin, p. 66-81.

Ostrom, M. E., 1967, Paleozoic stratigraphic nomenclature for Wisconsin: Wisconsin Geological and Natural History Survey Information Circular 8.

Rose, L., and Vincent, P., 1986, The Kamenitzas of Gait Barrows National Nature Reserve, North Lancashire, England, in Paterson, K., and Sweeting, M., eds., New directions in karst: Anglo­French Karst Symposium Proceedings, September 1993, p. 497-514.

Rosen, C., 1984, Karst geomorphology of tbe Door Peninsula, Wisconsin: unpublisned M.S. Thesis, University of Wisconsin-Milwaukee, 119 p.

Rosen, C., Day, M. J., and Piepenburg, K., 1987, G1aciokarst depressions in tbe Door Peninsula, Wisconsin: Physical Geography, v. 8, p. 160-168.

Schneider, A. F., 1990, Door County's glacial heritage; A foundation for tbe future, in Hershbell,·K. E., ed., Door County and tbe Niagara Escarpment; Foundations for tbe future: Wisconsin Academy of Sciences, Arts and Letters Conference Proceedings, October 1989, p. 15-35.

Schroeder, J., Beaupre, M. and Cloutier, M., 1986, Ice-push caves in a platform limestone of tbe Montreal area: Canadian Journal ofEartb Sciences, v. 23, p. 1842-1851.

Sherrill, M. G., 1978, Geology and ground water in Door County, Wisconsin, witb emphasis on contamination potential in tbe Silurian dolomite:U .S. Geological Survey Water-Supply Paper 2047,38 p.

Stieglitz, R. D., 1990, The geologic foundation ofWisconsin's Door Peninsula, in Hershbell, K. E., ed., Door County and tbe Niagara Escarpment; Foundations for tbe future: Wisconsin Academy of Sciences, Arts and Letters Conference Proceedings, October 1989, p. 3-14.

Stieglitz, R. D., Moran, J. M., and Harris, J. D., 1980, A relict geomorphological feature adjacent to tbe Silurian Escarpment in northeastern Wisconsin: Wisconsin Academy of Science, Arts and Letters Transactions, v. 68, p. 202-207.

WiIliams, P. W., 1966, Limestone pavements: Institute of British Geographers Transactions, v. 40, p. 155-172.

52

EUROPE LAKE SEDIMENT CORES AND VEGETATION IDSTORY

William N. Mode Department of Geology

University of Wisconsin-Oshkosh Oshkosh, Wisconsin 54901

Louis J. Maher, Jr. Department of Geology and Geophysics

University of Wisconsin-Madison Madison, Wisconsin 53706

INTRODUCTION

Europe Lake occupies a small basin near the tip of the Door Peninsula. The lake is separated from Lake Michigan by a sand bar and dune complex (Fig. 8 in road log). The main objective of coring Europe Lake was to date its isolation from Lake Michigan through growth of the bar and dunes. On February 22, 1992, AlIan Schneider, Marty Koopman, Coggin Heeringa, and the authors collected three cores from the southern part of the lake (Fig. 9 in road log) using a modified Livingstone piston corer. We collected the cores in approximately 2 m (6.5 ft) ofwater, and sediment recovery varied between 1.9 and 2.3 m. After extruding the cores on the ice, we sampled the uppermost few centimeters of flocculent sediment and sealed the remainder in plastic wrap and aluminum foil. Cores were unwrapped, measured, described, and sampled in a clean palynology laboratory and then re-wrapped for cold storage .

. SEDIMENTOLOGY

The sediment in all three cores ]s mainly gray marly gyttja. Beneath the gyttja is a thin (1 to 11 cm) peat or duff layer that contains wood, bark, and other plant macrofossils. In two of the cores, diamicton (5 cm) was recovered beneath the peat. The brown color and sandy texture of this diamicton resemble that of the till of the Liberty Grove Member of the Horicon Formation (Mickelson and others, 1984).

In the upper 130 to 140 cm ofthe gyttja, fossil mollusks (whole valves) occur in discrete partings, usually one or two shells thick, and not distributed throughout the sedimento Beneath this, mollusks are more abundant and are uniformIy distributed throughout the gyttja. In the lowest 25 cm of gyttja, shell fragments become increasingly abundant.

Correlation of the three cores can be accomplished by matching color changes in the gyttja. The uppermost few centimeters of highly flocculent gyttja is light olive gray; beneath that is 12 to 15 cm of dark-gray gyttja, which is under!ain by 48 to 53 cm of light-gray gyttja. This pattern of color alternations occurs throughout the gyttja. Near the base of the gyttja a thin bed (2 to 4 cm thick) of white mar! serves as a useful marker. Partings of fossil mollusks sometimes correlate between cores, but sometimes they do noto

CHRONOLOGY

A small sample (0.7 gm of carbon) of peat from irnmediately beneath the gyttja in core 1 (214-220 cm) was dated at 6,610 ± 150 yr B.P. (Beta-56310). The sample contained several small fragments of wood and bark but, nevertheless, required extended counting time. This provided a maximum age for initiation of gyttja deposition; for a number of reasons gyttja deposition may have begun more recently

53

tban 6,600 B.P. No otber dates have been obtained because of tbe potential for hard-water (reservo ir) effect. Because tbere are several well-dated poli en diagrams from lalces in east-central Wisconsin (West, 1961; Goodwin, 1976; Davis and otbers, 1986; Webb, 1987), we use tbe regional pollen stratigraphy and tbree pollen counts from tbe lower part of core 1 (190, 199, and 210 cm) to date tbe beginning of sedimentation in Europe Lalce.

PALYNOLOGY

There are tbree chronostratigraphic boundaries in pollen diagrarns from tbe region tbat have potential for dating tbe Europe Lalce gyttja and tbereby tbe isolation of tbe basin. The youngest is tbe historic ragweed (Ambrosia) rise tbat occurred at about A.D. 1850. Preliminary pollen counts place tbis boundary between 20 and 30 cm deep in Europe Lalce core 1.

American beech (Fagus grandifolia) migrated into tbe Europe Lalce area about 4,000 B.P. and eastern hemiock (Tsuga canadensis) reached tbe vicinity between 6,000 and 5,000 B.P. (Davis and otbers, 1986). The samples from Europe Lalce core 1 at levels 1.90, 199, and 210 cm all contain Fagus and Tsuga pollen. This suggests tbat lalce sedimentation began several tbousand years afier tbe date of tbe underIying peat.

FI'ax. Pinus QueI'cus Tsuga AlIIbI'osia Picea Betula Ullllus Fagus AI'telllisia OtheI'(9)

'J!I' BP , · • • , • - -Est. , • - • - • - - -, :' - • ::' • - , -• - • • - • -• - - • - ., · -• - - • - • - -• - - • - • - -• - - • - - • • 2000 , ¡¡¡, = , ¡¡, , , , ..,

• =- • • • , • - • - • • , -• - - • - · • • , -• - - • • , - • • -, - - • - • • , • 1 ~ - ~ - · • \ , ~ , = :::l , , - - • - : • • , -- - • - • , , -- - • - • , , • -· - • - - • , • · • ~ - - , ! • -3700 ::1 ::J 1 , , ii' :::- ~ - • , - • -- • - • -- • - • -- • - ':' -- - - -- - - • -- · - • = - - - • - • - -· • • - • • • - • • • ==- : - -· - -• - - - -• - · - -• - · - -, =-- • - -- , , • -- , , • - - -- , , , - - -- , • ~ = ~ - • • • - -- • • - - -- • • • - - -- • • - • -

EUI'ope Lake uso Seidel Lake H 20:1.

Figure 1. Three pollen samples from Europe Lake (open bars) inserted into the sequence of pollen samples from Seidel Lake (West, 1961). The Europe Lake samples from depths of 190, 199, and 210 cm match the Seidel Lake samples in the interval estimated to range from 2,000 to 3,700 B.P. The tick marks at the right mark every ten samples.

54

The nearest site from which a pollen diagram is available is 100 km to the southwest at the base of the Door Peninsula -- Seidel Lake in Kewaunee County (West, 1961). There are no carbon dates available from the original Seidel Lake cores. However, its sediment contains the ragweed rise of the last century; the basin lies on moraine of Greatlakean age and must postdate that ice advance. It is possible, using palynology, to correlate Seidel Lake with Kellners Lake, which lies an additional 35 km southwest in Manitowoc County (Goodwin, 1976). Thus the Kellners Lake 14C chronology can be carried to Seidel Lake and ultimately to Europe Lake.

Figure 1 shows a pollen diagram of Seidel Lake in which the Europe Lake samples (open bars) have been inserted by a mathematical "slotting" technique. The three samples from the base of the Europe Lake gyttja lie in the sequence estimated to range from 2,000 to 3,700 yr B.P. This suggests there was a hiatus of at least 3,000 years from the last accumulation of peat to the initial accumulation of gyttja.

ACKNOWLEDGEMENTS

Marty Koopman and Coggin Heeringa assisted with the coring. Marty Koopman, Andy Day, Steve Franklin, Robert Weseljak, Don Wendorf, and Tara Zwicky assisted in the laboratory with core description and sampling and with sample preparation.

REFERENCES ClTED

Davis, M. B., Woods, K. D., Webb, S. L., and Futyma, R. P., 1986, Dispersal versus climate; Expansion of Fagus and Tsuga into the upper Great lakes'region: Vegetation, v. 67, p. 93-103.

Goodwin, R. G., 1976, Vegetation response to the Two Rivers till advance based on a pollen diagram from Kellners Lake, Manitowoc Co., Wisconsin: unpublished M.S. thesis, University of Wisconsin"Madison. . .

Mickelson, D. M., Clayton, Lee, Baker, R. W., Mode, W. N., ami Schneider, A. F., 1984, Pleistocene stratigraphic units of Wisconsin: Wisconsin Geological and Natural History Survey Miscellaneous Paper 84-1, 97 p.

Webb, S. L., 1987, Beech range extension and vegetation history; Pollen stratigraphy of two Wisconsin lakes: Ecology, v. 68, p. 1993-2005.

West, R. G., 1961, Late- and postglacial vegetational history in Wisconsin, particularly changes associated with the Valders readvance: American ]ournal of Science, v. 259, p. 766-783.

55

MOLLUSCAN FAUNAL CHANGES IN EUROPE LAKE, WISCONSIN DURING THE PAST 6,600 YEARS

Barry B. MilIer Department of Geology Kent State University

Kent, Ohio 44242

INTRODUCTION

The author has had an ongoing interest in the timing and nature of the changes that have affeeted the molluscan faunas in the Great Lakes sinee deglaciation (MilIer and Kott, 1989). This preliminary study is based on molluscs reeovered from one of a series of three 2-m cores collected from Europe Lake and represents an extension of these investigations to an afea of the Lake Michigan basin that 1 have not previousl y examined.

STRATIGRAPHY

The stratigraphy in the three eores is quite similar (pers. comm., W. N. Mode). A radioearbon date of 6,610± 150 yr B.P. (Beta-56310) on peat at a depth of 214 cm from eore 3 suggests that the sediments in the cores started to aceumulate in the Europe Lake basin during the rise in the water level in the Lake Michigan basin from the low-water Lake Chippewa phase.· The sediments are predominantly a silty gyttja that have been subdivided into 13 units based on color changes. A summary description of the sediments recovered from core 2 are given in Table 1.

Unit DEPTH (em)

1 Oto 15 2 15 to 29 3 29 to 38 4 38 to 64 5 64 to 66 6 66 to 95 7 95 lo 100 8 100 to 121 9 121 to 131 10 131 lo 142 11 142 to 170

12 170 to 178 13 178 lo 192

Table 1. DESCRIPTION OF CORE 2 LITHOLOGY

Description

Silty Gyttja; dark grey (7.5YR 3/1) Silty Gyttja; light grey; (7.5YR 512) Silty Gyttja; dark brown grey (7.5YR 3/2) Silty Gyttja; Iight grey (IOYR 5/1) Gyttja; with > 2 mm plant fragments; dark grey (10YR 3/1) Silty Gyttja; grey (IOYR 4/1) mSm:mi LOST~~~ Silty Gyttja; grey (10YR 4/1) Silty Gyttja; dark grey brown (7.5YR 5/2) Silty Gyttja; dark grey (IOYR 3/1) Silty Gyttja; with dark-grey (IOYR 3/1) and Iight-grey (lOYR 4/1) bands Marly Gyttja; light grey (10YR 612) Gyttja and Mari; light-grey marls bands(10YR 5/2) and dark organic-rich bands (IOYR 4/1). Wood at 191-cm.

57

MATERIALS ANO METHOOS

The molluscs were recovered from a 192-cm core collected with a Livingstone sampler. The core was split, and starting at the core top al-cm subsample for ostracodes and a 4-cm subsample for molluscs was recovered at each lO-cm incremento The 4-cm samples were dried and washed through a series of 25 to 35 mesh sieves. A total of 1,776 individuals was counted. Ten species of molluscs were identified from these niaterials (rabie 2). The overwhelming majority of individuals belong to two species of prosobranch gastropods, Marstonia decepta and Valvata tricarinata. All the species are stillliving and have geographic ranges that include the study area.

Table 2. FAUNAL LIST OF MOLLUSCS FROM EUROPE LAKE CORE

TAXON ABUNOANCE

GASTROPOOA

Marstonia decepta 1070 252

Va/vata tricarinata 48

Amnico/a limosa 60 Helisoma anceps 48 Fossaria obrussa

9 Gyrau/us parvus 1

Planorbella campanu/atum 7 Physa sp.

1495 •

PELECYPOOA

Pisidium ferrugineum 46 32

Pisidium ventricosum 195 Pisidium spp.

8 Musculium partumeium

281

INTERPRETATION ANO DISCUSSION

Europe Lake is now apparently fed by ground-water discharge and precipitation. This inference is based on the observation that a 6-m elevation difference now exists between the Europe Lake and Lake Michigan water planes.

The molluscan fauna from between 170 and 185 cm includes a mixture of depauperate, broken and etched gastropod shells that occur in association with relatively abundant pisidiid c1ams. The condition of many of the shells suggests that they may have been exposed to subaerial weathering before burial.

58

Valvata tricarinata undergoes a significant increase at 160 cm and remains the most abundant species to 130 cm, where it is replaced in this dominance role by Marstonia decepta. Species diversity and abundance changes at a depth of between 120 cm and 130 cm divide the core into upper and lower molluscan faunal zones (Fig. 1). Below this depth, Marstonia decepta is less abundant than Valvata tricarinata, and these two species usually occur in association with Amnicola limosa and the pulmonate gastropods, Helisoma anceps and Fossaria obrussa. Above this interval, the two pulmonate species are almost totally absent, and Marstonia deceota overwhelms every other taxa in terrns of abundance. These changes in molluscan species diversity and abundan,e can be explained most parsimoniously in terms of water-level changes in the Europe Lake basin.

Shallow water below the 160-cm level is implied by the presence of Fossaria obrussa and Helisoma anceps, species that usually are found associated with abundant submerged vegetation in permanent water that is seldom morethan 50 to 100 cm deep (Burch and Jung, 1987). At this time the water depth at the core-2 site was shallow and supported an abundant aquatic macrophyte flora. The aquatic vegetation probably included Pomatogeton richardsoni and Myriophyllum exalbescens, two plants that are commonly found associated with Helisoma anceps, V. tricarinata and M. decepta (pip, 1978). The radiocarbon date from the base of core 3 of 6,600 yr B.P. suggests that the low-water level in Europe lake coincided with (1) the Nipissing transgression in Lake Michigan when the lake was still rising from the low-water Lake Chippewa phase (Larsen, 1987), and (2) a time when pollen records from the upper Great Lakes region suggest a warm, dry climate (Miller and Futyma, 1987).

The changes in species diversity and abundance, coupled with the almost total absence of pulmonate (air-breathing) snails from the upper molluscan faunál zone are interpreted as representing a time' when the water level in Europe Lake deepened. The irnmediate cause of this deepening was probably the rise of the Lake Michigan water plane to the 183-m Nipissing I level (Larsen, 1985). This event would either have inundated the Europe Lake basin or at least elevated the local water tableo

The replacement of Y. tricarinata by M. decepta as the dominant species might also be due to deepening of the water in Europe Lake. It is interesting to note here that water chemistry data compiled by Pip (1986) for aquatic gastropods from 412 sites in centralCanada suggest that y. tricarinata (::;;480mg/l) has a greater tolerance for chloride than M. decepta (::;; 8mg/l). Is it possible that the water chemistry in Europe Lake during the warm, dry climate inferred for the early Holocene from the pollen . record (Miller and Futyma, 1987) may have resulted in slight increases·in dissolved chloride that would have favored V. tricarinata? Higher water levels in Europe Lake would have resulted in dilution of the chloride and may have permitted M. decepta to compete more effectively with V. tricarinta.

The increase in water depth would reduce the area of shallow-water habitats near the coring site that supported the air-breathing pulmonates and probably led to their reduced abundance.

Although the water level in Lake Michigan subsequently lowered when the moderno drainage system through Port Huron became established (Larsen, 1987), the water level in Europe Lake remained relatively high, possibly in response to the onset of cooler, moister late Holocene climates indicated by many of the pollen records from the upper Great Lakes (Miller and FU!yma, 1987).

59

EUROPE LAKE CORE 2 MOLLUSCA

GASTROPODS PELECYPODS

I I

Marstonia decepta V. tricarinata A.limosa H. anceps F. obrussa Other Pisidium Pisidum Pisidium spp. Musculium ferrugineum ventricosum partumeium

l' 11 l' I I 1 I I I I I I I ¡¡ I I I l' I I I I F'l F'l F'l F'l Fl rnl I i ¡ 1I I ( ¡ m o 50 100% o 25% o 25% o 25% o 25% o 25% o 25% o 25% o 25% o

",;pTU utllT

" " " " " " '" " "

'" u, no , DO

" .. , '" u

'" 170 .

" '" " ""

<.05 I - ....

<.05 <.05 <.05 <.05

<.05 <.05 <.05 <.05

-, ... <.05

<.05 <.05 <.05 <.·05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05

<.05 <.05 <.05

<.05

m l' 1II l' I I F'l .Fl Fl Fl Fl rnl o 50 100% o 25% o 2-5% o 25% o 25% o 25% o 25% o 25% o

Figure 1. Relalive frequency of moIluses in core 2. Numbers in Ihe 'UNIT" column lo Ihe righl of the "DEPTH" scale refer lo Ihe lithologic units in Table 1. The two arroWS lo Ihe right of Ihe Musculium partumeium column indicale that less Iban 20 individuals were counled from Iha! leve!.

<:

'" o CIl en <: =ªo ON E-

'" ~ <: CIl :::J

8:.s . :::J

C:' ar '" <: ,~ o :::J N 15ai E§ ~'" CIl-;= .2

ACKNOWLEDGMENTS

Thanks are extended to Drs. Allan Schneider, William Mode, and Louis Maher, who collected Ihe cores and made Ihem available for study.

REFERENCES CITED

Burch, J. B., and Jung, Y., 1987, A review of Ihe classification, distribution and habitats of Ihe freshwater gastropods of Ihe North American Great Lakes: Walkerana, v. 2, p. 233-291.

Larsen, C. E., 1985, A stratigraphic study of beach features on Ihe soulhwestern shore of Lake Michigan; New evidence of Holocene lake level fluctuations: Illinois State Geological Survey Environmental Geology Notes 112, 31 p.

__ ,1987, Geological history of glacial Lake Algonquin and Ihe upper Great Lakes: U.S. Geological Survey Bulletin 1801, 36 p.

Miller, B. B., and Kott, R., 1989, Molluscan faunal changes in Ihe Lake Michigan basin during Ihe past 11,000 years: National Geographic Research, v. 5, p. 364-373.

Miller, N. G., and Futyma, R. P., 1987, Paleohydrological implications of Holocene peatland development in northern Michigan: Quaternary Research, v. 27, p. 297-311.

Pip, E., 1978, A survey of Ihe ecology and composition of submerged aquatic snail-plant cornmunities: Canadian Journal of Zoology, v. 56, p. 2263-2279.

__ , 1986, The ecology of freshwater gastropods in Ihe central Canadian region: Nautilus, v. 100, p. 56-66.

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61

•

I

I

I

I

I

I

THE OSTRACODE RECORD FROM EUROPE LAKE, WISCONSIN: THE PAST 6,600 YEARS

Alison J. Smitb and Beiwen Dai Department of Geology Kent State University

Kent, Ohio 44242

INTRODUCTION

The Europe Lake ostracode fauna provides a record of temporal changes in a small lake basin on tbe edge of Lake Michigan. Altbough probably affected during tbe past 6,600 years by tbe rise and fall of tbe Lake Michigan water level, Europe Lake has apparentiy remained isolated from Lake Michigan. There is no evidence of tbe ostracode fauna from Lake Michigan (Colman and otbers, 1990) in tbe Europe Lake core, even as reworked or transported material. The fauna presented here are characteristic of a small, dilute caIcium-magnesium-bicarbonate lake typical of tbose found tbroughout tbe Great Lakes region (Smitb, 199i).

METHODS

Three cores were taken from Europe Lake, one of which was radiocarbon dated. The tbree cores are· stratigraphically very similar (pers. cornm., W. N. Mode). The date of 6,610 ± 150 yr B.P. (Beta-56310) on peat from tbe base of core 3 is tbe source of tbe chronology in tbis analysis. Core 2 was described and sampled as discussed by Miller (tbis volume). Ostracode samples were taken from core 2 at lO-cm intervals, each witb a wet volume of 6 ce. Ostracodes were processed byfreezing tbe samples, mixing ihem witb hot (90 0 C) water buffered witb baking soda, and tben further disaggregated witb Calgon. The mixture of water and sample was tben washed tbrough a stack of tbree sieves of 20, 100, and 230 mesh. The size fractions were bagged, frozen, and freeze dried. The lOO-mesh size fraction contained most of tbe ostracode material. AH unbroken adult ostracode valves were counted in each sample.

RESULTS

Thirteen taxa of ostracodes are represented in tbe core, all of which are living in tbe region today (Table 1 and Fig. 1). The lower portion of tbe core, from 190 to 160 cm, is almost devoid of ostracodes. Many of tbose tbat are present are broken or abraded. The core section from 160 to 120 cm contains a large number of ostracode valves representing a permanent lacustrine fauna of Candona ohioensis, .c;. inopinata, .c;. distincta and Limnocytbere verrucosa. Species associated witb groundwater discharge, such as Candona elliptica and Darwinula stephensoni, and nektonic pond species, such as Cypridopsis vidua, are also present in abundance. The upper portion of tbe core, from 120 cm to tbe sediment-water interface, differs substantially from tbe lower part oftbe coreo Above 120 cm, tbe species associated witb permanent lake conditions decline, whereas tbose species tbat do well in more variable conditions, such as Cypridopsis vidua, increase.

63

o-~

.

Europe L., WI eore 2

é,9 ¿j.\oe""",

Analyst Beiwen Oai

• C)\.6 0",0 • AO~\<' . r-c\'C) ~e;

~ r-'<>o . ~e<;t~e ~\o\).o

~,~6 0(6<:f.

s(t< R 6 ~ ~(~,oe(' ~\~'Ó.cC) o cC)~~{< of:' C6('O~C)

O \,. ~i;;'<:> ~e co('oo<' o~o d-~e(e c6f:' 'I)~('o

'¡.,,('..y.6 ,i}.'" fJO('i- cfloOY

..J<;t~'" ~C) "'~ ~<;tll .~(('. :(Qe\ ~o'" ~\' '", ~ 0"- ",~~ 1?O .... ~ 1?~i'IfF "cFi<;t(' cF'l'Y~"',,'Y~'"

ole; oIG1 01C\cF'

20

40

60

,?eo o

'1:: 100 .... Q.

~12O

140

180

180

200

0203.2 640 306090120 02040 D 2040 O 6613.2198264020400 BB 1762640130 80 1800 2B04D8 number of valves/6 ce sample

Figure 1. Ostracode diagram foc Europe Lake, Wisconsin, COte 2.

Table 1. OSTRACODE SPECIES PRESENT IN EUROPE LAKE, CORE 2

Cyclocypris ampla Cyclocypris ovuni Cyclocypris sharpei Physocypria spp. Cypridopsis vidua Potamocypris smaragdina Darwinula stephensoni

Candona distincta Candona elliptica Candona inopinata Candona ohioensis Candona paraohioensis Limnocythere verrucosa

INTERPRETATION AND DISCUSSION

Tbe ostracode record indicates two major changes in the history of Europe Lake after 6,600 years B.P. Tbe first change occurs at 160 cm depth, and the second occurs at 120 cm depth. Tbe lower portion of the core, from 190 to 160 cm depth, is indicative of a very low water marsh, with subaerial exposure and possible erosion of fossil ostracodes from terraces aboye the present lake. Tbe molluscan • record from this part of the core supports this interpretation by the presence of pulmonate snails (Miller, this volume). Both the molluscs and the ostracodes are abraded and broken, indicating transport, reworking, and subaerial exposure. At 160 cm depth, species characteristic of a permanent lacustrine environment appear. Tbe abundanceof shells in the interval from 160 to 120 cm indicates either high productivity or a low sedimentation rateo Tbe water composition and concentration can be inferred from similar ostracode assemblages found in the region today, suggesting that the lake contained Ca-Mg-HC03 water, with concentrations that did not exceed 450 mg/L (Smith, in press). We interpret this permanent lacustrine condition as one associated with the rise in the Lake Michigan basin (the Nipissing transgression) following the low-water Lake Chippewa phase. Tbe presence of Candona elliptica and Darwinula stephensoni suggeststhat groundwater discharge was also important.

Above 120 cm depth, the number of ostracode valves declines for aH but a few taxa. Cypridopsis vidua and Limnocythere verrucosa are species tbat are associated with more variable lakes and ponds. Tbe moHusc fauna indicate a deepening at the core site for this interval, based on the increase in Marstonia decepta'and the disappearance of pulmonate gastropods (Miller, this volume). A water-level rise in the lake at the core site is not clearly indicated by the ostracode fauna, but the change to a more variable, less permanent condition is indicated. Tbere is no evidence that the lake water ever exceeded 450 mg/L in total concentration or has had a composition other than Ca-Mg-HC03. An oxygen isotope record from the ostracodes in the core would confirm a shallowing or deepening of the lake.

Although the water level in Lake Michigan is approximately 6 m below the core site today, Europe Lake continues to existo Graund-water discharge and atmospheric precipitation obviously supply the lake, and have probably done so since the decline of Lake Michigan water levels in response to the establishment of the Port Huran drainage system (Larsen, 1987).

ACKNOWLEDGMENTS

We thank AlIan Schneider, Williarn Mode, and Louis Maher, who collected the cores and made them available for study. We also thank Barry Miller for helpful discussions on the Great Lakes records and the moHuscan ecology.

65

REFERENCES CITED

Colman, S., Jones, G., Forester, R. and Foster, D., 1990, Holocene paleoclimatic evidence and sedimentation rates from a core in southwestern Lake Michigan: Journal of Paleolimnology, v. , p. 269-284. .

Larsen, C. E., 1987, Geological history of glacial Lake Algonquin and the upper Great Lakes: U.S. Geological Survey Bulletin 1801, 36 p.

Smith, A. J., 1991, Lacustrine ostracodes as paleohydrochemical indicators in Holocene lake records of the north-central United States: Ph.D. dissertation, Brown University, Providence, R.l.

__ ' in press, Lacustrine ostracodes as paleohydrochemical indicators in lakes of the north-central United States: Journal of Paleolimnology.

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66

NEWPORT VILLAGE: A WILDERNESS EXPERIMENT

Coggin Heeringa Newport State Park

ElIison Bay, Wisconsin 54210

In 1837, Sylvester Sybly made tbe first survey oftbe nortbern Door Peninsula. "Soil-- second rate" was his assessment for tbe area tbat is now Newport State Park.

Jt is unlikely tbat tbe pioneers ever saw his reporto They carne full of drearns, laboring under the misconception tbat land which could support huge trees must be more fertile tban grasslands. So settlers, predominantly German, Scandinavian, and Bohemian, carne into nortbern Door County to remove tbe valuable timber and at tbe sarne time to "improve tbe land for agriculture." Sadly, in tbis area tbeir best crops were rocks, and what was once wilderness has now reverted to near-wilderness.

A few farmers settled in tbe area in tbe 1870s, and in 1880 a Dane named Hans lohnson acquired 200 acres of timberland and witbin ayear announced to tbe world (or at least to readers of tbe Door County Advocate) tbat he planned to start a town. And he did, at a site now used as tbe picnic/beach area in Newport State Park.

Newport Bay is notoriously shallow, so during tbe first summer lohnson put in an enormous pier, a series ol' cribs supporting planks. By autumn tbe.pier was being used, altbough it wasstill incomplete. Two schooners were anchored at tbe pier when tbe fabled gales of November blew in from tbe east. According to tbe Door County Advocate of November 17, 1881, "Hans lohnson's new pier at Newport, near Rowleys Bay, was pretty badly demolished during tbe heavy gale from tbe east last Friday night. Two vessels, tbe scows "Forrest" and "Becker," were Iying alongside tbe structure at tbe time, when tbe storm drove tbem ashore and tbe pier was carried out with tbe vessels." The next issue reported tbat "immediately after tbe accident, Mr. lohnson, witb his characteristic energy and enterprise, went to work to rebuild tbe pier, and it will not be long before everything about Newport will be in a flourishing condition again. Whoop-Ia."

lohnson did more tban rebuild his dock. He stored tbe battered schooners in his barn, and when tbe owners offered tbem for sale at bargain prices lohnson purchased tbe R. H. Becker. By 1882, he owned tbat scow schooner, a pier, and a block of heavily timbered land. The people living in and around Newport referred to tbe entrepreneur as "Governor" Hans lohnson. A benevolent "governor," he built a general store-post office and cooperated witb neighbors to establish tbe Newport school at tbe site now occupied by Unele Tom's candy kitchen.

In tbe early years of tbe community, tbe forest commodity most in demand was cordwood. Following tbe Great Chicago Fire of 1871, brick became tbe building material of choice. The Milwaukee brickyards' insatiable appetite for hardwood provided a market for tbousands of cords of beech and maple from Newport each year. The Becker carried wood products to Milwaukee and Racine, returning witb goods for tbe store and building materials for tbe growing community. In addition to brickyard wood, lohnson sold shipments of fine maple, basswood, and birch to tbe Two Rivers Manufacturing Company and bolts of poplar to tbe new pulp mili in DePere.

As settlers pushed into America's West, a market grew for virgin pine lumber and otber forest products. During tbe 1887 season,,Johnson sold 11,000 cedar and hemlock railroad ties and 20,000 posts in Milwaukee, Racine, and Chicago.

67

Forest industries at Newport were not limited to wood production. In the 1880s, oil distilled from cedar was a major component of furniture polish, and from 1885 to 1887 this distillate was produced on the shores of Rowleys Bay. Johnson also shipped out more than a hundred cords of hemlock bark, the source of tannin used in leather production.

Johnson usually had at least 20 men working in his woods. They were paid one dollar a cord for wood -- cut, hauled, and banked on ·the Newport beach. When word arrived that a schooner was approaching, men and boys ran to the pier where 25 cents an hour was paid for loading wood. Considered a generous wage, this money helped many immigrants purchase land, which they c1eared for farming. Primarily woodcutters and farmers, the men of Newport would drop whatever they were doing, however, when fishing would bring in larger profits.

But even in times of prosperity, life was incredibly harsh. Tiny log cabins were chinked with moss to keep out the frigid lake winds. Scarlet fever and diphtheria were common and often fatal. In bad times, Johnson extended credit or just gave food lo the needy. Farm yields from the rocky lands often were insufficient for even home consumption. The community survived on hope and timber.

Times for Johnson were bad too. His wife Anna died in 1887. By most accounts, though not obvious at first, this loss marked a turn-around in the governor's fortunes. He began to drink heavily. In 1890, his pride and moneymaker, the R.H. Becker, capsized near Ahnapee with one man drowning. The cargo sank and the schooner, deemed irreparable, was sold at an enormous loss.

A lighthouse keeper on Pilot Island, Peter Knudson, kept his savings in Hans Johnson's safe at Newport. According to credible sources, when Johnson became short of money he began to dip ¡¡ito Knudson's savings, planning to pay it back in the future. By the time Peter Knudson returned to shore lo check on hiscash, Johnson had drunk up Knudson's entire savings. Whatever might have transpired between the Iwo men, by 1892 Peter Knudson had become Johnson's partner and was appointed Postmaster at Newport. Captain Knudson continued his career with the lighthouseservice and also sailing the ship "The South Side" between Newport and other Lake Michigan ports.

During the 1890s, the village boasted a population of 300, including a pump manufacturer, a wagon maker, a shoemaker, and a blacksmith. But Johnson lost another boat, the "Lettie May," in the Sturgeon Bay ship canal and continued to lose money on every wood shipment. By 1895, he had sold the remainder of his business and much of his property to Peter Knudson for $2;000 and left the area, but he returned several years later to work for his former partner.

Knudson employed a large force of woodchoppers and teamsters who worked under foreman Hans Johnson. When Knudson was gone, working for the lighthouse service or sailing, Johnson also ran the store and pier. But by the turn of the century, the village of Newport was slowly transforming into an agricultural community. Knudson continued to carry logs from Newport to Milwaukee, but in addition to wood he carried cargos of grain and potatoes.

Hans Johnson was also elected to serve as Liberty Grown Town Treasurer. But by 1905 the whispered reports of a scandal became publico Buried in the Advocate, a small item read "It is now definitely known that the deficit in the account ofTown Treasurer Hans Johnson is approximately $2,750, an expert having gone over the books during the past weeks ... The defalcation did not surprise any one who had kept in touch with the trend of affairs in the treasurer' s office for the past year or so."

The rumors Were true. Johnson had drunk up the town funds, bringing the area bondsmen to financial ruin and rendering the town helpless to pay even its school teachers. Accepting the charity of friends, Johnson returned to the farm he once owned and attempted to retrieve his losses. Several months

68

later the Advocate reported that he was dying of tuberculosis. Finally, ex-Assemblyman, ex-Town Treasurer, ex-"Governor of Newport," Hans Johnson accepted ajob in the forests of the Upper Peninsula and was never heard from again.

Lake shipping was slacking off, so in 1908 Peter Knudson established a large saw, shingle, and lath mili on the shores of Newport Bay. At first lumber was shipped elsewhere, but the area was growing and twenty employees were kept busy doing custom milling for local farmers.

At the same time, the northern end of Door County was establishing a reputation for natural beauty. The tourist industry was born. The only problem was lack of transportation. Autos were few and roads abominable. Tourists could not reach northern Door, nor could area farmers find eco no mi cal markets . for their produce. So when, in 1913, a group of investors proposed a railroad from Sturgeon Bay to Newport, a stock issue of $75,000 was eagerly snatched up by area subscribers. This golden opportunity was not lost on Knudson. His son Herbert went to Sturgeon Bay to work out details of the plan with railroad surveyors while Knudson entered into a contract with the development firm, E.E. Gane Company. This company helped Knudson plat an elaborate crescent-shaped city stretching from Europe Bay south to Rowleys Bay. The property was subdivided into 751 lots, most of which were intended for summer homes.

Newport was surveyed and a crew of workers began clearing and leveling the twenty planned streets. Unfortunately for Knudson, the railroad plan fen through. Except for a sman commission, investors got their money back, and most patriotic citizens reinvested their money in war bonds, for World War 1 loomed even on the Door County horizon. Not wanting to pay taxes on platted land, Knudson petitioned to vacate the plan. Courthouse records state, "None of the streets or avénues or public beaches or public places indicated on said plat have been used or occupied or accepted by the public in any way whatsoever. None of the avenues or streets have been laid out or opened or worked or made fit for travel, or improved in any way whatsoever. NOTHING has been accepted by the public."

There would be no railroad, no town, and probably no more shipping. In 1919, 37 years after its beginning, the village met its end. Newport VilIage had become a farm. In the Sturgeon Bay Advocate the headline read "Peter Knudson Holdings in Liberty Grove Sold to Ferdinand Hotz." Hotz was a Chicago diamond merchant who summered in Fish Creek; he purchased 1,015 acres, including the Newport buildings. According to the newspaper account, Hotz had originany intended to subdivide the shoreline lots and sen them as resort property'. But instead the Newport area became a Hotz family retreat. Most of the land remained in the Hotz family until 1964, when the land and rotting ghost town were purchased by the Wisconsin Department of Natural Resources for use as a state park. What was once wilderness is now wilderness again.

Editor's Note: Mrs. Heeringa is the naturalist at Newport State Park and also writes a column for the Door County Advocate. This article is excerpted from a chapter on the history of Newport that will appear in a forthcoming book.

69

1

BEACH RIDGES AND LAKE-LEVEL IDSTORY AT TWO RIVERS, WISCONSIN

Eric Dott Delta Environmental Consultants, Inc.

St. Paul, Minnesota 55112

INTRODUCTION

Point Beach State Forest and nearby Woodland Dunes Nature Center encompass two beach-ridge complexes located north and south, respectively, of the mouth of the East and West Twin Rivers at the city ofTwo Rivers on the western shore ofLake Michigan (Fig. 1). The beach-ridge complexes preserve a record of Holocene lake-level fluctuations and shoreline progradation. The oldest ridges may be as old as 4,000 to 5,000 yr B.P. The ridges east of County Highway O along the access road to the park office building have been dated from 3,000 yr B.P. to modern (Dott, 1990).

DESCRIPTION

The northern or Point Beach ridge complex is composed of 0.5- to 8-m high, closely spaced subparallel ridges that trend north-south. The complex is bordered on the west by the broad, flat Molash swamp. West ofthe swamp is a sharp wave-cut till scarp with associated dune sands trending north from the Two Rivers Moraine at Two Rivers. This scarp forms the western limit for the Holocene lake deposits (Fig. 1). The ridges in the Point Beach complex are separated by narrow low swales, which in many locations are filled with standing water, wetland vegetation, and accumulated peat deposits.

The Woodland Dunes ridge complex covers a smaller area. Ridges at this site are interspaced with wide swampy swales arranged in a fan-shaped pattern. These ridges and s'wales diverge to the north, where they are truncated by the Twin Rivers lowland. This ridge complex is also backed on the west by a poorly developed wave-cut terrace (Fig. 1).

DETERMINATION OF PAST LAKE LEVELS

Beach ridges represent positions of past shorelines. The ridges are dune capped and have a core of back-beach laminated sand over foreshóre coarse-grained laminated and cross-laminated sediments. The foreshore deposits extend beneath the adjacent lakeward swale. Foreshore sediments are underlain by rippled cross-laminated or parallel laminated fine- to medium-grained sands of the upper shoreface facies.

Former lake-level elevations, represented by foreshore deposits beneath the lakeward sides of beach ridges, have been dated with radiocarbon dates obtained from peat deposits in swales between the beach ridges (Dott, 1990; Thompson and others, 1988). Auger drilling, closely spaced vibracoring, and ground-penetrating radar profiling along two east-west transects, one at Point Beach and the other at Woodland Dunes, provided the subsurface data and age-dating material with which to reconstruct the lake-level history for this area (Fig. 2). Tables 1 and 2 surnmarize the radiocarbon dates from the two sites.

71

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Figure 1. Map of \he Two Rivers area showing beach-ridge lineations and longshore drift patterns.

72

l·

TABLE 1. RADIOCARBON DATES FOR POINT BEACH TRANSECT (Transect A-A')

Material S.mple # Date' Reference # t doted (thicknessttl glevutlnn (m a.s.l.)

Tranucr A-A' (sites Usted (rom eosl lo weSl );

Mn·5·11·88·3 (Entrance swalc) modero ISOS·1948 wood and basal pea! . 177.2 m (6 cm)

Mn-5·1I·88-1 (Osta8c swalc) 620 +/- 80 Beta·29618 wood Crom peal 176.6

Mn·I6-IQ.88·IB (ThundcrslOml swalc)" 1,180 +/- 70 ISOS-1937 wood in peal 178.1

Mn-\S·IQ.88-3B (wcs.\ Molash swamp) 1,630 +/- 70 ISOS-2055 upper peal 176.9

Mn-31-8-88·1 (Snakcswalc) 1,390 +/- 130 IS05·1935 basal peal 177.5

Mn·26-8-88·3 (CIam .wale) 1,540 +/- 70 ISOS·1957 (9 cm)

basal peal 177.7 (6 cm)

Mn-16-1Q.88-1 (Thunde:suxm swalc)" . 1,600 +/- 70 1505·1934 basal peal 178.0

Mn·5·11·88·5 (Hwy '0' .wale) (9 cm)

3,150 +/- 110 Beta·29220 basal peal 175.6 (13 cm)

Mn·15·1Q.88-3 (wCSI Molash swamp) 4.750 +/. 90 ISOS·1958 buricd peal layer 176.2 (9 cm)

Mn-87.()7-12-3 (wCS! MoIash swamp) 5,740 +/. 120 Beta·2SS66 basal pea¡ 174.5 (6 cm)

t.!n·I23 (WI Molash swamp) 5,970 +/- 80 ISOS'1936 drifiwood Crom sand 162.0 abovc red clay diall1ic1

, Radiocaroon dates are repor1ed as 'coovcn~onal'date in Radlocarbon y .... beCore !he .. fcrcnce ycar A.D. 1950. ISOS dalCS are co",:clCd . for uOlOplc Cracllonacton, bUI are nol eorreclcd for!he error in 14c half·me. ,. 5ame sile. t lIIinoi. Stato Geolo~ícul Survey,

Radiocarbon Iaboratory and Beta Anal~c, Inc., COfllI Oables, Florida 33124. tt Thicknesó oC peal horizon dOled.

TABLE 2. RADIOCARBON DATES FOR WOODLAND DUNES TRANSECT (Transect B-B')

Sample #

Mn·¡¡·9-88·5 (Wooduckswalc)

Mn-1Q.9·884B (Musl:nI1 swaIc)

Mn-IQ.9·884 (Musl:nI1 swaIc)

Material Dute' Reference # t dOled (thicknesstt) ~:Iev.tinn (m a.s.I.)

Transeet B-8' (sites listed (rom taSI (O west);

4,380 +/- 90 ISOS·1933 basal peal 180.3 m

5,640+/- 90 ISOS-2056 basal peal 179.6 (29 cm)

6,100 +/- 90 ISOS-I947 detrital wood from 179.3 sand below peal

, Radiocarbon dates are reponed as "convcnoonal" date in Radlocarbon years before!he .. Cuenco year A.D. 1950. ISOS dates are correclCd for isolopic Cractionacton. bUI are no! corrccted CO!!he error In 14C half·life. ,. Same sit •. t Illlnols Stato Oeologicul Survey, Radlocarbon Iaboratory and Beta Analytic, Inc., COfllI Oables, Florida 33124. tt Thíckncss of peal horiwn dated. .

73

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Figure 2. Hypo!hesized late Holocene lake-Ievel trends at Two Rivers based on stratigraphy, morphology, and radiocarbon dates atPoin! Beach State Forest and Woodland Dunes NalUre Center .. Stippled pattem denotes lake levels defined by elevation ranges of abandoned shore fealUres and associated trangressive sediments. Vertical bars constrain salid curve based on range of stratigraphic indicators and radiocarbon dates; curve is dashed where inferred. Remaining dates are plotted as points (boxes) on curve. The post-Algoma curve defines only !he high lake levels at Two Rivers; evidence from southem Lake Michigan (Larsen, 1985, 1987, 1990) indicates that lake level a1so fell below the modem mean elevation during lhis periodo

BEACH-RIDGE FORMATION

.Formation of a new beach ridge may occur in response to a chaoge in lake level, a chaoge in sediment influx to the shoreline, or a combination of these factors. Figure 3 illustrates the features of the beach ridges aod swales aod their relationship to a modern shore environment.

Sediment accumulation aod probably beach-ridge formation are processes that occur in localized settings along a shoreline reach, where coastline structure, longshore drift, aod· a sediment source combine to form a progradational beach-ridge complex such as at Two Rivers (Reineck aod Singh, 1986; Curray aod others, 1967). The ridges aod swales on the entraoce road to the park contact station are typical of the Point Beach ridge complexo Vegetation on back-beach dunes helps to stabilize aod build up the dunes which typically cap beach ridges (Fraser aod Hester, 1977; Davies, 1957; Shepard, 1960; Bird, 1960; McKenzie, 1958). The initial ridge may be a low wave berm or exposed miar-shore bar which then is built up by vegetation entrapment ofwind-blown beach saod. With favorable low lake level aod net accumulation of sediment along the shore reach, the ridge may be preserved by a vegetated dune cap (Dott, 1990; Fraser aod Hester, 1977; Curray aod others, 1967; Psuty, 1965).

74

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Figure 3. Schemalic diagram of ridges and swales showing localions of basal peal deposita used lo date !he formation of adjacent lakeward beaches. Organic delrital malerial is assumed lo have I1ccumulaled shortly after !he formalion of a new ridge.

RIDGE ALIGNMENT AND STRUCTURE

Chariges in a1ignment of lhe beach ridgeS occur at bolh of lhe ridge complexes at Two Rivers, resulting in eíght distinct groups of subparallel ridges (Fig. 1). Such realignments result in lhe truncation of part of lhe ridge complex produced by charige in sediment suppIy, water level, or wave energy (Reineck arid Singh, 1986; Curray arid olhers, 1967).

Stratigraphic cross sections (Figs. 4 arid 5) arid ground-penetrating radar profiles indicate lhat lhe ridge complexes are composed of a series of discontinuous stacked lenses of beach deposits distributed laterally arid dipping towards lhe lake. This pattern reflects lhe progradational growth of lhe ridge complexes. Realignments of lhe shoreline are seen in lhe subsurface ground-penetrating radar profiles as lakeward dipping erosional contacts lhat originate at lhe Iocations of ridge realignments. There are at least seven such realignments of lhe ridge pattern arid eight groups of parallel ridges, as shown in Figure 1.

LAKE-LEVEL HISTORY AT.TWO RIVERS

The lake-leveI history interpreted from cores a10ng lhe transects A-A' (Fig. 4) arid B-B' (Fig. 5) is based on lhe rarige of elevations obtained by measuring lhe eIevation of lhe top arid base of foreshore deposits benealh beach ridges. The timing of lhe lake-level chariges was determined by dating basal peat deposits from swales between beach ridges arid detrital wood deposited in transgressive sarids. The elevations of lhe tops of foreshore deposits formed in lhe last 3,000 years rarige between 0.2 arid 2.0 m above lhe modern meari lake level. The elevation of lhe base of lhe foreshore deposits for lhe last 3,000 years rariged from -0.3 to + 1.7 m relative to modern mean lake elevation (Fig. 2). Using lhe base of lhe foreshore as lhe best lake-Ievel indicator, lake level at Two Rivers apparently has reached as high as

75

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1.7 m aboye modern mean lake level for sufficient lengths of time to deposit foreshore deposits during the past 3,000 years.

The overall pattern of the foreshore deposits in the outer beach ridges at Point Beach shows no extreme elevation changes. Resolution of lake-Ievel changes of less than ± 0.5 m would be difficult to achieve using the aboye method of mapping the foreshore. This is due to uncertainties caused by the variability in the overall thickness of the foreshore deposits, which ranged from 0.25 to 1.0 m thick; by possible errors in eore measurement and deseription of ambiguous facies contaets; by resolution of surveyed elevations fOf features with variable· topography, such as beach-ridge crests (survey measurements were calculated to an accuracy of ± 0.01 m); and by difficulties in determining the attitude and position of the foreshore in the subsurface between widely spaced core localities.

The elevations plotted in Figure 2 for the past 3,000 years only apply to lake level highs during this periodo It is possible, of course, that unrecorded low-water levels occurred between the times of high level represented by the mapped foreshore deposits.

The Holocene lake-level history of the Two Rivers shore can be interpreted in two ways based upon the stratigraphic evidence and in the larger context of Lake Michigan basin lake-Ievel chronology. For the Lake Michigan basin, three major transgressions (Nipissing I, Nipissing II, and AIgoma) have been identified between 6,500 and 3,000 yr B.P. (Hansel and Mickelson, 1988; Larsen, 1985). For the Two Rivers site, the Holocene lake-Ievel fluctuation curve (Fig. 2) indieates that at least three major transgressions occurred, at about 6,500 yr, 4,800 yr, and 4,300 yr B.P. A fourth lake-Ievel rise occurred around 3,200 yr B.P.

As stated, the Holocene lake-Ievel history of the Two Rivers shore can be interpreted in two ways from the stratigraphic evidence. One interpretation assigns an early transgression to a level aboye 180 m eleva!Íonbefore 6,100 yr B.P., which coincides with the Nipissing I event describedby Hansel and Mickelson (1988). The second transgression of 179 m high, around 4,800 yr E.P., equates with the Nipissing II transgression (Hansel and Mickelson, 1988). Progradation combined with alto 2 m drop was followed by the AIgoma transgression, whieh raised lake level back up to 181 m at 4,500 to 4,300 yr B.P. (Fig. 2). The shore then prograded eastward as the lake gradually dropped; smaller 1 to 1.7 m lake-Ievel fluctuations (above modern mean) occurred throughout the period from 3,000 B.P. to present.

A second interpretation attaches younger ages to the Nipissing I and II transgressions of 4,800 to 4,200 B.P. (Fig. 2). In this scheme, the AIgoma transgression would be assigned a date sometime younger than 3,400 yr B.P. The most recent events, from 3,000 B.P. to present, are the same for either interpretation. .

The lake-Ievel fluctuation curve of Figure 2 applies only to the Two Rivers area; comparisons with other sites should take into consideration differenees in isostatic uplift within the Lake Michigan basin. Maximum lake levels at the Illinois Beach area, aceording to Larsen (1987), rose to 1.5 m aboye modern mean lake leve!" over the past 3,000 years. Larsen (1985, 1987) also found evidence of low lake levels that suggest that the lake dropped as low as -1.5 m during this same time periodo

Thompson (1990) has studied the stratigraphy ofbeach ridges in northwest Indiana at the southern Lake Michigan shore using vibracoring methods similar to those used for this study. He reports that the elevation changes of the base of foreshore deposits in the Indiana Dunes National Lakeshore area reach up to 2.0 m aboye modern-day mean lake level (176.3 m) for the last 3,000 years.

The locations of Larsen's and Thompson's study areas are south of the zero isobase line of isostatic uplift of the controlling outlet at Port Huron (Larsen, 1985, 1987; Thompson, 1987). Because

78

of isostatic uplift of the northern lake basin relative to the southern lake basin, the southern Lake Michigan shore would have experienced a slight transgression of the lake during the last 3,000 years. This rise in lake level at the southern Lake Michigan shore due to isostasy would be superimposed on climatically induced lake-level changes. However, there is no significant difference between the high lake levels at Two Rivers (1.7 m) and the sites to the south (1.5 m, Larsen, 1987; 2.0 m, Thompson, 1990). The isostatic change appears to be too small to resolve for the last 3,000 years.

REFERENCES CITED

Bird, E. C. F., 1960, Formation ofsand beach ridges: AustralianJournal ofScience, v. 23, p. 349-350. Curray, J. R., Hemmel, F. J., and Crampton, P. J., 1967, Holocene history of a strand plain lagoonal

coast, Nyarit, Mexico, in Castanares, A. A., and Phelger, F. B., eds., Coastal lagoons; A symposium: Universidad Nacional Autonoma, Mexico, p. 68-100.

Davies, J. L., 1957, The importance of cut and fill in the development of sanct beach ridges: Australian Journal of Science, v. 19, p. 107-109.

Dott, E. R., 1990, Stratigraphy and lake level history of a beach ridge complex at Two Rivers, Wisconsin, on the northwest shore of Lake Michigan: unpublished M.S. thesis, University of Wisconsin- Madison, 222 p.

Fraser, G. S., and Hester, N. C., 1977, Sediments and sedimentary structures ofa beach-ridge complex, southwestern shore ofLake Michigan: Journal of Sedimentary Petrology, v. 47, p. 1187-1200.

Hansel, A. K., and Mickelson, D. M., 1988, A reevaluation ofthe timing and causes ofhigh lake phases in the Lake Michigan basin: Quaternary Research, v. 29, p. 113-128.

Larsen, C. E., 1985, A stratigraphic study of beach features on the southwestern shore of Lake Michigan; New evidence of Holocene lake level fluctuation: Illinois State Geological Survey Environmental Geology Notes 112, 31 p.

__ , 1987, Long term trends in Lake Michigan levels, a view from the geologic record, in Wilcox, D. A., Hiebert, R. D., and Wood, 1. D., eds:, Proceedings of the First Indiana Dunes Research Conference; Symposium on shoreline processes:U. S. Department of the Interior, National Park Service, Science Publications Office, Atlanta, Georgia, 52 p.

__ , 1990, Isostatic uplift rates and the reconstruction of lake level changes in the Lake Michigan­Huron basins: U.S. Geological Survey Open File Report 90-272, p. 7.

McKenzie, P., 1958, The development of sand beach ridges: Autralian Journal of Science, v. 21, p. 213-214.

Psuty, N. P., 1965, Beach-ridge development in Tabasco, Mexico: Annals of Association of American Geographers, v. 55, p. 112-124.

Reineck, G. E., and Singh, I. B., 1986, Depositional sedimentary environments: Springer-Verlag, Berlin, 549 p.

Shep¡u:d, F. P., 1960, Gulf coast barriers, in Shepard, F. P., Ph1eger, F. B., and vanAndel, T. H., eds., Recent sediments, Northwest Gulf of Mexico: American Association of Petroleum Geologists, Tulsa, Oklahoma, p. 197-220.

Thompson, T. A., 1987,Sedimentology, internal architecture and depositional history of the Indiana Dunes National Lakeshore and State Park: unpublished Ph.D. thesis, Indiana University, Bloomington, Indiana, 308 p.

__ , T. A., 1990, Preliminary assessment of late Holocene lake-level variation in Lake Michigan: U.S. Geological Survey Open File Report 90-272, p. 6.

Thompson, T. A., Fraser, G. S., and Olyphant, G., 1988, Establishing the altitude and age of past lake levels in the Great Lakes: Geological Society of America Abstracts with Programs, v. 20, p. 392.

79

•

Hydrogeology and Water Quality in the Fractured Dolomite Aquifer, Door County, Wisconsin

I ntrod uction

Kenneth Bradbury and

Maureen Muldoon

Wisconsin Geological and Natural History Survey

The majority of residents in Door County rely on the fractured Si/urian dolomite aquifer as their sole source of groundwater. The area has a history pf elevated nitrate, chloride, bacteria, and occasionally, lead levels in groundwater samples collected from private and public wells. Such contamination is believed to be a direct result of agricultural and other land-use practices in areas where thin soils overlie the fractured dolomite. Soil cover is thin over much of Door County, providing little pollution attenuation potential. Numerous fractures in the dolomite control the hydraulic conductivity of the bedrock aquifer. Each fracture, if open, can provide a direct route for infiltrating water to recharge the groundwater flow system. (see figures 1 & 2)

Background In May 1984, the Upper Door Watershed was selected as a Priority

Watershed under the Wisconsin Nonpoint Source Water Pollution Abatement Programo The Upper Docir Watershed Project is unique in Wisconsin's Nonpoint Source Pollution Program beca use it is the first wátershed project selected primarily for the purpose of protecting and improving groundwater quality.

The agencies working on the Upper Door Priority Watershed Plan desired a measure of the effectiveness of nonpoint pollution containment measures in reducing groundwater contamination. Despite many previous studies and sampling programs, the existing data were not sufficient to allow any definitive statements about the existing groundwater quality in Door County. Therefore, the Wisconsin Geological and Natural History Survey (WGNHS); in cooperation with the Wisconsin Department of Natural Resources (DNR), the Door County Soil and Water Conservation Department, and UW-Green Bay; initiated a study to 1) determine background concentrations of water quality parameters, 2) quantify spatial and temporal variations in groundwater quality in a portion of northern Door County, and 3) characterize the groundwater flow system in the county.

81

Results Water Ouality

1. Long-term monitoring of 14 existing domestic wells indicates that water quality is quite variable through time and that single groundwater samples may not provide an accurate picture of groundwater quality for a given well (see figure 3). These large variations in groundwater quality may be due to rapid groundwater movement through fractures. Water quality parameters measured include nitrate, chloride, turbidity, conductivity, sulfate, potassium, and bacteria.

2. Although water quality is quite variable, some general trends can be noted (se e figure 3). The four domestic wells plotted in figure 3 are located within 5 miles of the research site. The fact that such widely spaced wells show similar trends in groundwater quality parameters suggests that the contamination sources are diffuse, nonpoint sources that cover a broad area of the landscape.

3. Sixty-five domestic wells and five springs were sampled on a regular basis between February 1986 and August 1987; sampling has continued at 14 wells through June 1990. These samples indicate that 60% of the wells had bacteria present more than 25% of the time (25% was assumed to be due to sampling errors resulting in false positives) and 16% of the wells had average nitrate concentrations in excess of the 10 mg/l drinking water standard (NO; as N).

Flow system 1. There are two flow systems in the fractured dolomite aquifer. At the study site,

there is a shallow water table, 20 to 40 ft below the land surface and a deep potentiometric surface 'at approximately 150 ft below the land surface. Previous "water-table" maps of the area were based on measurements in deeply cased domestic wells and they incorrectly delineated a deeper potentiometric surface as the water table. A shallow water table means that contaminants applied at the land surface can enter the groundwater flow system more easily than previously assumed.

2. A very conductive fracture zone, located about 170 ft below the land surface, leads to very high groundwater velocities. A numerical model of the study area indicated that groundwater can move at rates up to 1.5 mile/yr (22 ft/day). A tracer test, conducted at the study site, indicated that groundwater in the deep flow system can travel as rapidly as 75 ft/day (5 mile/yr). While these values are not in perfect agreement, both suggest that groundwater velocities are quite high.

3. Water levels fluctuate over a wide range at the research site and both systems respond rapidly to snowmelt events, indicating that they are directly connected to the land surface. (see figure 4)

4. Pump tests indicate that the hydraulic conductivity of the deep zone is much greater than that of the shallow zone.

5. Seasonal recharge events can cause temporary reversals in the regional groundwater gradient. Since groundwater flow directions are controlled by the hydraulic gradient, such reversals make it difficult to accurately predict groundwater flow directions. (see figures 5 & 6).

82

Figure 1 Numerous vertical and horizontal fractures in the dolomite apparently control the hydraulic conductivity of the aquifer. Photo shows near,vertical fracture expression in an alfalfa field across from the Sevastopol research site. The near'vertical fractures are filled with fine'grained soil, which holds more moisture than surrounding rocks. The photo shows the frequency and regularity of fracture spacings. Horizontal fractures are also relatively common at the site. Geophysical logs, including television logs, indicate several high-conductivity horizontal fractures at depth. (see figure 2)

83

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Figure 2. Geophysical 109s for well MW1 at the Sevastopol site. Dashed horizontal lines indicate horizontal fracture zones.

84

EXPLANATION OF GROUNDWATER QUALlTY PARAMETERS Nitrate is a form of nitrogen that is commonly derived from fertilizers and animal

wastes. The recommended public drinking water standard is 10 mg/l of N03" as N. A mg/l is 1 part per million. In natural groundwater nitra te levels are low, usually under 2 or 3 mg/l. Nitrate is easily dissolved in water and it is not attracted to soil particles; as a result it is a good indicator of groundwater movement. High nitrate levels are sometimes an early warning that other contaminants may be in the water.

Figure 3 Plots of nitrate-N values versus time for four domestic wells in northern Door County. Dashed vertical lines mark the beginning of calendar years. AII the wells show a significant increase in nitrate-N concentrations occurred in all four wells in December 1987, followed by a gradual decrease in concentrations during the spring of 1988. Other simultaneous changes in concentration include an increase in October 1986, December 1988, and April 1990.

20

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1986 1987 1988 1989 1990

85

Figure 4 Graph showing the water-Ievel fluctuations for the shallow and deep systems. Significant temporal water-Ievel fluctuations occur at the Sevastopol test site, and water-Ievel fluctuations in the deep zone are greater than in the shallow zone. Water levels in piezometer MW2A, finished in the deep system, fluctuated by up to 95 ft in response to seasonal recharge. The most significant water-Ievel rises occurred just after snowmelt in March, 1988. Well MW3, finished in the shallow zone, fluctuated only about 45 ft during the observation periodo

The rapid response of the shallow and deep piezometers to spring snowmelt suggests that both systems are directly connected to the land surface. The two systems respond differently during dry periods. The water level in MW3 (shallow system) drops sharply and then stabilizes at approximately 740 ft above sea level (depth 55 ft); the water level in MW2A (deep system) continues to drop steadily throughout the summer. The large and rapid water-Ievel fluctuations in the deep system probably are caused by the presence of pror'ninent conductive fracture zones not present in the shallow system.

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..0700 ()

.,.J

<i-650 '--/

°600 « W I

550 J

, , M,17C~ "l I ,

I - , I , I '1 \ , '-, ,

A JJASO 1990

MW3

MW1 l MW2DMW6A . L L

MW7C L

MW2A

L

Figure 4-5. Hydraulic head of wells and piezometers at the Jarman Road site. Unes on the right side of the figure indicate the open interval of the well or piezometer; Asterick indicates when MW7C was dry.

86

I I .

POTENTIOMETRIC SURFACE

SEPTEMBER 1989 MARCH 1990

Figure 5. Configuration of the potentiometric surface in the 15 mi2 subarea of central Door County in September 1989 and March 1990. Contour interval is 20 ft.

SHALLOW WATER TABLE

SEPTEMBER 1989 MARCH 1990

Figure 6. Configuration of the water table in the 15 mi2 subarea of central Door County in September 1989 and March 1990.

87

•

THE TWO CREEKS BURIED FOREST

Robert F. Black

Reprinted from Wisconsin Geological and Natural History Survey Information Circular 13, 1970

INTRODUCTlON

Two Creeks is a small town 10 miles norlh of Two Rivers, near the west shore of Lake Miehigan in east­central Wiseonsin (Fig. O. James W. Goldthwait in 1905, while studying abandoned shorelines of eastern Wis­eonsin, observed portions of a buried forest soil with trees and logs exposed along the lakesho;e southeast of the town. His report (Goldthwait, 1907) brought to the seientifie eommunity a brief deseription of what has sinee beeome an internationally famous stratigraphie horizon, the Two Creeks Buried Forest. The time interval represented in part by the buried forest has been ealled Twoereekan (Frye and Willman, 1960). It is a substage of the Wiseonsinan Stage (Frye, Willman, Rubin, and Blaek, 1968), and as suggested by them, represents the radioearbon interval about 11,000 to 12,500 years B.P.

This find of buried organie malter was not the fírst in Wiseonsin. Notiees of buried wood in southern Wis­eonsin go baek to the 1840's, and Whittlesey (Owen, 1852, p. 436) mentioned !he presenee of buried wood in a dug wel! at Appleton, 45 miles west of Two Creeks. Lawson (1902) and Thwaites (1943, p. 136) mention other loealities. Beeause of its exposure along the lakeshore, the Two Creeks site was visited frequently, even though it was not studied in detail for deeades after its diseovery.

Wilson (1932 afid 1936) fírst started detailed studies of the fossil assemblages of trees, mosses, mollusks, inseets and pollen. A stratigraphie seetion appeared in Alden (1932, p. 43). Thwaites and Bertrand (1957, pp. 855-864) summarized the available information on the geology of the loeality whieh was one of the stops for INQUA, Exeursion C (Blaek, Hole, Maher, and Freeman, 1965) and other fíeld trips (e.g., Thwaites, 1953; and Prouty, 1960). Other workers eheeked partieularly on mosses (Culberson, 1955), pollen (West, 1960, and radioearbon age (Broeeker and Farrand, 1963). The site also has be en used in a Committee for Institutional Cooperation (CIC) Instruetional Improvement Program (Blaek, Clark, and Hendrix, 1968). Several other loeali­ties with equivalent-age butied forest horizons are now known in Wiseonsin (Fig. 19), but the type loeálity is slill the best exposed and best known.

Several isolated oeeurrenees of !he buried forest are found along Ihe lakeshore in the vieinity of Two Creeks. That whieh is most aeeessible today is direetly south of the Kewaunee-Manitowoe County line at a smal! temporary shelter (Fig. n. The property is owned by The Nature Conservaney and is being held as part of the future "Ice Age National Seientifie Reserve" of Wiseonsin (National Park Serviee-Wiseonsin Depart­ment of Natural Resourees, 1968).

OUTLlNE OF STRATlGRAPHY

In the bank of Lake Miehigan, whieh rises today about 30 feel above water level (Fig. 5), is a detailed sequenee of deposits (Fig. 6) whieh .depiet vast ehanges in elimate and in geologie events from a time perhaps 14,000 radioearbon years ago to the presento Stratigraphieally, the bank shows at water level a eompaet, red to gray elayey till and massive lake deposits of similar appearanee (5 YR 6/3 Iight reddish brown to 7.5 YR

• 6/2 pinkish gray dry and 5 YR 5/2 reddish gray to 2.5 YR 5/4 reddish brown wet). The till and massive lake sequenee eontain small amounts of silt, sand, gravel, and eobbles. Aeeording to well logs, the !ill rests di­,eetly on the Niagara dolomi te of Silurian age whieh is 40 to 80 feet below lake level. The till grades imper­eeptibly upward and laterally into the massive lake sequenee whieh, in turn, grades into rhythmieally bedded elay with some sil! and sand. The rhythmieally bedded deposits loeally extend from below lake level to as mueh as 20 feet above. The till and lake deposits represent !he Late Woodfordian glacial sequenee whieh was deposited probably between 14,000 and 12,000 radioearbon years ago.

Above !he rhythmieally bedded deposits loeally are layers of yellow-brown sand and gravel from a few inehes to 4 fee! thiek. They are considered shallow water, near shore, and beaeh deposits resulting from wave and eurrent aetion on the underlying deposits. The buried forest (Figs. 8-10) rests on and is formed in !he beaeh and lake deposits. The buried soil profile varies markedly aeeording to whether it is developed in the rhythmieally bedded clayey sequenee or in the eoarser sands and gravels. The forest horizon ranges gen­erally from 1 ineh to 12 inehes in thiekness, but loeally is cut out. It is undulating in the bank (Fig. 7), in part related to genUe knob and swale topography on whieh !he soil formed and in part due to warping by Ihe overriding Valderan ice. Trees in it are radioearbon dated at 11,840 years B.P. (Broeeker and Farrand, 1963). The most mature tree, aeeording to published information, has 142 growlh rings. AlI the larger pieees of trees

89

22

and stumps in the shelter are spruce (B. F. Kukachka, Forest ProducIs Lab., Madison, Wis.). While spruce eories are common in the plant debris.

On top of the forest bed are Iighl yellow to dark yellow lake sands, fine to coarse in texture. Locally, red colors are presenl. The sands are a few inches to 6 feel thick, bul locally are also absent. They contain numerous fragments of organic matler and portions of reworked soil. They are considered lo be the resul! of lhe rising lake level in front of Ihe advancing V.lders ice.

On top of them rests 2 to 12 feet of red (5 YR 6/3 Iighl reddish brown dry lo 2.5 YR 5/4 reddish brown wet) clayey liII of Valderan age, estim.led at 10,000 lo 11,500 radiocarbon years B.P. The till contains por­tions of the soi! and logs incorporaled from the buried soil, and local patches of sand incorporated from lhe lake deposits above and below the foresl soi!. Vertical prismatic fracture is pronounced in exposed cliffs in marked contrasl to the Late Woodfordian lill.

Local lake accumulations consisling of massive lo well-bedded sands are found on top of the till. They are as much aS 4 feet thick. The finer porlions are cornmonly red sill and very fine sands from the reworked Valders till; Ihey are inlerstratified with coarser yellow-brown sands and sorne gravel. Presumably they were laid down during the waning of the Valderan ice. A modero soil disrupted by plowing is formed in the Valderan till and in local patches of the youngest lake sands.

Woodfordian border

• Twocreekan organic matter in burlad deposit, wilh aga in radiocarbon years. ,

Flg. 19

90

23

TWOCREEKAN RADIOCARBON DATES SHOWN ON FIGURE 19

Date County Sample No. Material Remarks

12,800±220 Jefferson WIS-48 Spruce In basal peat

12,410±lOO Ozaukee WIS-347 Tamarack In basal peat

ll,560±350 Dane W-2015 Tamarack In basal peat

ll,611±600 Sauk M-812 Charcoal In fire pit

ll,130±600 Jackson W-1391 Wood In sand under peat in meander scar

12,800±400 Waushara UCLA-632 Organic 4 feet aboye bottom of kettle

12,OOO±500 Waushara W-641 Peat Under lake clay-silt

12,220±250 Waushara W-762 Peat Under lake clay-silt

12,060±700 Winnebago W-1l83 Peat and spruce Under till

11,790 Average Outagamie L698D Spruce Under till

11,840 Average Outagamie L698B • Spruce In buried soil

ll,640±350 Outagamie W-l110 Tamarack In buried soil

11,840 Average Manitowoc L698C Wood 6 to 12 inches below buried soil

ll,140±300 Brown W-590 Wood Under till

ll,940±390 Brown Y-147x Wood Under till

12,200±350 Shawano W-2357 Spruce With pond depo;its

12,900±300 Vilas 1-3780 Organic Basal lake deposits

DESCRIPTION OF THE BURIED SO/L

The buried soil is generally only a fey¡ centimeters thick, varying locally apparently in degree of develop­ment because of former topography, moisture, and texture of material, and in part by truncation from subsequen! rising lake waters. An incipient Podsol, with impeded drainage (Udorthent) similar to that under northern coni­fers in sorne wetlands today, typifies much of the soil on former knobs; in bogs and swales transported organic litter is characteristic.

A typical sequence Ihat represents a fairly thick profile a! one point at the shelter follows (Hole, 1967):

Depth Below Surface cm

IIOlb 492-494

IIAlb 494-498

IIA21b 498-505

IIA22b 505-525 and Bhirb

IIClb 525-535

Black (lO YR 211, moisO mucky peat; weak fine platy, plates consisting of dense mat of organic fibers and shreds, including twigs and rools; friable; medium acid (pH 6.0); abrupt wavy boundary. (O to 1 cm thick.)

Black (lO YR 2/D silt loam to muck; massive to strong fine platy; friable; medium acid to moderately alkaline (pH 6.0 to 8.0), with effervescence of discrete particles when f100ded with dilu!e HCl; abrupt wavy boundary.

Gray to light gray (lO YR 5/1-7/D fine sandy loam; with distinct to prominent, few medium motiles of dark yellowish brown to yellowish brown (lO YR 4/4-5/6). These occur adjacent to joints or crack s in the substratum; sorne of the brown-coated joints extend clear through Ihe solum in place s, up inlo the overburden; massive; friable; calcareous; abrupt wavy boundary. (5 lo 15 cm thick.)

Grayish-brown to gray (lO YR 5/2-5/D fine sandy loam with 15% of surface, particu­larly along joints, occupied by prominent coarse motUes as described aboye; locally a gravelly sand loam; massive; friable; calcareous; clear smooth boundary. (15 lO 30 cm thick,)

Grayish-brown (lO YR 5/2) silt loam and fine sandy loam wilh sorne pockets and seams oC gravel; iron stains along joints, as described aboye, but somewhat fewer~ massive¡ friable; calcareous.

91

24

Particle size, free rerríe oxide, and calcium carbonate equivalent are shown in Table 1 fOI another buried profile near the shelter, and for eomparison with the modern soil aboye it.

O. B. Lee and F. D. Hole (1970, ms.) elassify the buried soil as a typie Udorthent.

"The modern soils in the eultivated field are naturally well drained, developed in 15 to 75 cm of loamy covering over Valders till, and inelude two phases of the Hortonville loam, a Oray-Brown Podzolie tran­sitional to Podzol. On rises is a weakly developed bisequal soil (Alfie Haplorthod of the new elassinea­tion system: Soil Survey Staff, 1960, 1967) in whieh a Podzol soi! profile is faintly developed in the mid­die of the A horizon of a somewhat degraded Oray-Brown Podzolie (Alfie Haplorthod). In slight depres­sions the ineipient Podzol is not present and the surfaee soil (Ap horizon) is relatively thiek and dark (Mollie OlossudaIO."

A profile of the modero soi! follows (O. B. Lee and F. D. Hole, 1970, ms.):

Soil Profile Hortonville loam, dark surfaee variant.

Ap 0-25 cm Blaek (10 YR 2/1 moisO and grayish-brown (10 YR 5/2 dry) loam; modera te medium granular strueture; friable moist; neutral to alkaline; abrupt boundary.

A2 25-36 cm

Bl 36-46 cm

IIB2t 46-71 cm

IICI 71-102 cm

II C2 102-224 cm

Brown (10 YR 5/3 lnoisO and pinkish-gray (7.5 YR 6/2 dry) fine sandy loam; weak medium platy strueture; plates break into weak medium subangular bloeky aggregates; patehy, yellowish-brown (10 YR 5/2 dry) stains on ped surfaees; friable moist; a few pebbles; alkaline; elear boundary.

Brown (7.5 YR 5/4 moist) and Iight brown (7.5 YR 6/4 dry) silt loam; moderate, fine to medium, subangular bloeky strueture; pinkish-gray eoatings on ped faces; slightly sticky wet, hard dry; alkaline; elear boundary.

Reddish-brown (5 YR 5/3-4/3 moist) elay loam; moderate, eoarse prismatie strueture, prisms break into strong, medium angular bloeky peds; sticky wet, hard dry; a few peb­bies; alkaline;' elear boundary.

Reddish-brown (5 YR 5/3 moisOloam to elay loam; moderate, eoarse prismatie struc­ture; prisms break into moderate, medium, angular bloeky peds; stieky wet, hard dry; a few, mainly dolomi.tie, pebbles and eobbles; ealeareous matrix; gradual boundary.

Reddish-brown (5 YR 5/3 moisO elay loam; eoarse prismatie strueture; prisms break into eoarse bloeky peds; light brownish-gray (2.5 YR 6/2 moist) coatings on vertical faces of prisms. These eoatings effervesee strongly in dilute acid; ped interiors effer­vesee moderately; a few, mainly dolomitie, pebbles and eobbles; abrupt boundary with underlying pro-Valderan mud flows.

92

. Table 1. Some anaIytieaI data for two soils at tbe Two Creeks Site, Manitowoe Count¡y, Wisconsin'

MODERN SOIL

Hortonville loam, dark suJt'face variant (Mollie GlossudaIf')

P. S. Dislribution' Horizon & Depth (cm)

G' S' Si' C' Free CaCO,

------------------- % -----~~~~--_:~~~:-O (0.541)

Ap (0-25)

A2 (25-36)

B1 (36-46)

HB2t (46-71)

HC1' (71-102)

IVCS" (368-406)

o 35

Ir. 60

N.O. N.O.

Ir. 31

16- 39

O 28

'Data from Lee and Hole (1970)

47 18 1.52 O

24 16 0.58 O

N.O. N.O. N.O. O

34 35 1.69 O

36 25 0.67 40

60 12 0.45 57

2Classification according to the new soil classification system of the V.S.D.A. (Soil Survey Staff, 1960, 1967)

lParticle size distribution 'G = gravel (2.0 mm dia.); nol included in tbe sum of s, si, and c which total 100%

BURlED SOIL

Twoereekan peat¡y loaro, buried variant (Fibristie Udortbent')

P. S. Dislribution' G' S' Si' C' Free CaCO, Horizon &

Depth (cm) '" Fe,O, equiv. ------------------- ~ -----------------VOb (406-414)

. VlBgb (414-434)

VlC1b (434-440)

VlIC4b'" (460-4801

10

Ir.

10

39

82

s

'S' = sand (241.05 mm dia.> 'Si = silt (0.0541.002 mm dia.) 'c = clay (0.002 mm dia.) 'Valders till 'Pro-Valders mud f10w "Glacial Lake Chicago deposits

41 20

11 7

64 31

N.O.

0.51

0.22

0.83

N.O.

35.2

42.0

34.0

.. <lO

26

DETAILS FROM EARLIER STUDlES

Because the earHer literature on the Two Creeks site is not widely available) sorne extracts and sum~ maries are presented here.

Goldthwait (1907. p. 61) wrote: "Two miles south of the village of Two Creeks (in seetion 24) the freshly cut lake eliff showed in July. 1905. a remarkable eross-section of an interglaeial fores! bed. Laminated red elays formed the base of the seetion. up to Iwo or three feet above the water. Above this. and separating it from a twelve-foot sheet of stony red till. was a eonspieuous bed of peat, stieks. logs and large tree trunks. whieh unmistakably represent a glaeiated forest .... The till immediately above the forest bed. besides eontain­ing eharactedstic subangular striated stones and red elay similar to the clay in the stratified beds below. all absolutely unassorted. was plentifully mixed with broken branches and twigs. In the underlying forest bed the stumps were well preserved. the wood being soft and spongy Iike rotten rubber. but retaining all the appearanee of its original strueture. Several logs and stumps lay pointing signifieanUy towards the southwest. the direc­tion in whieh the ice sheet probably moved at this place. One Iittle stump, however .... with its ramifying roots firmly fixed in the laminated red e1ays, stood ereet as when it grew there. but it had be en broken short off at the lop. where the ice sheet. dragging its ground-moraine along. had snapped off the top without uprooting the tree. Around eaeh root the red clay was discolored to a Iight drab. showing the effeet of acids derived by de­cayo in contact with the iron-bearing elays. There was no mistaking the only half-exeavated eondition of Ihe deposito Clearly this surfícial sheet of red till reeords a final advance of the ice sheet over a surface of lam­inated red e1ays. which here. at least. had be en clothed with a foresl. The trees were broken and generally overturned by the ice. and buried beneath the twelve-foot sheet of till. The wonder is that so much of the over~ridden forest should be preserved, and at leasl one stump in it rema in erect."

Goldthwait (1907. p. 59) also mentioned that at one point in the vicinity of Manitowoe a peal bed 3 feetlhick formed the upper part of the 10-fool,cliff. with laminated clays eontaining sticks and branehes be­low. In another place a bed of old logs and sticks ¡ay buried beneath 15 feet of clay. near the base of the cliff. Thus were recorded. in parto the location and descriplion of !wo segments of the Two Creeks Forest Bed.

No immediate study was made ofthe foresl bed although F. T. Thwaites visited the are a several times between 1922 and 1930. Wilson (1932) undertook a preliminary investigation and later amplified his work (Wilson.1936). He fírst studied the for"st,bed where it'was exposed for one-half mile along the lakeshore in sections 11 and 13. T 21 N. R 24 E. He al so mentioned that the same forest bed was exposed three miles to the north on the lakeshore and in a ravine about a quarter of a mile to the west in seetion 35. T 22 N. R 24 E. Kewaunee County.

Wilson (1932) studied closely the foresl bed for only about 100 feet along the lakeshore and through a vertical range of only several inches. He interpreted the fores! bed lO Iie 00 top of varv~d clays and sills and under additional laeustrine sil!s and sands deposited between the relreat of ice and its re-advance whieh laid down till on topo Locally the lake beds were 12 feet thiek. The till on top of the laeustrine sediments was about 8 feet thiek. At the site most of the wood is spruee (Picea mariana and Picea canadensis [glauca]) and hemloek. The wood is soft and easily broken and ehecks ana breaks into short seetions on drying. Tis­sues, however, are not destroyed and microscopic sections can be rnade of them. Where wood and peal are in contaet with the red till. there is a zone in the elay a few inches wide of greenish-gray color due to deoxida­tion of the iron. The logs oecur most frequenUy in the lacustrine sediments direeUy above the forest bed. but are al so in the overlying till. Wilson found one stump in silu with the butt of the broken log almost attaehed. The roots of this stump extended along the forest bed peat. On a portion of the root that had be en exposed above the ground during the interstadial period was found a braeket fungus. It is Polyporus but the speeies was not determined. AII the logs that had not been broken by subsequent handling showed ,agged splintered ends as a consequence oC glacial action.

Wilson (1932) studied the growth rings in seetions of six logs. The greatest number of rings in on. see­tion was 82; the average was about 60. Five of the logs showed by the width of suceessive ríngs a marked deerease in therate of growth in their last 12 years of !ife at the Two Creeks site. One log taken from lhe red till direeUy above the foresl bed showed IitUe deprease until the last year of its growth. That particular log was white spruce (?). Picep canadensis [glaucal. The first 5 logs were eonsidered by Wilson to represent the growing eonditions of the forest bed al the site. whereas the log taken from the till above was eonsidered as having be en Iransported by ice from a different environment farther north. When the log taken from the red till was eompared with the others. an extreme differenee in size and growth rate was notieeable. That log was twieé the diameter of any of the others although it had only the average number of growth rings. The width of

94

•

27

the rings did not agree with that of the forest bed trees. The growth rings could not be compared exactly with reference to particular years, because it was not

kno~n whether all the trees were destroyed in the same year or whether they were all alive at the time the ice adv.nced. However, Wilson considered il probable that the largest lag having been brought in by the ice was felled several years befare the trees that had grown at the site studied.

Detailed study of wood sections by Wilson showed that certain small rings of the forest bed trees oc­curred at years approximately corresponding to those in which wide growth rings occurred in the transported lag from the overlying till, and vice versa. Ir excessive moisture was one of the primary factors for small growth lÍngs in the trees, as is suggested by the character of the flora and fauna, then trees growing in higher ground would not have been similarly affected and probably would do better in wet years.

The moss f100r of the forest bed contained the most extensive group of plants found in the remains. The moss material, identified by L. S. Cheney, was divided into 19 species. AII the mas ses are of existing spe­cies but are in general more northerly in their modelO distribution than the Two Creeks Foresl Bed location. Nearly all are found in northern Wisconsin but the present southern Iimits of a rew are in Canada.

Peat in the forest bed was poorly formed and in some parts of the exposure was wanting entirely. Wilson (1932) concluded from this, as well as from some other organic remains, that the Two Creeks Forest Bed was not exactly a lowland forest but rather a dry forest at one stage of ils existence. In place s the mas ses and other plant remains accumulated as a silty peat such as can be found in any spruce forest today. 11 is from this peat that the microfossils were secured.

Seven species of mollusks were identified from the forest bed by F. C. Baker to whom Wilson sent speci­mens. These were from three levels in the forest bed. They agree ecologically with other organic remains from their respective horizons. One Pleistocene form was reported-from the clay immediately beneath the forest bed. The individual,s in higher levels represented existíng species.

The mollusk Fossaria dalli (Baker) was considered Pleistocene on the basis of its large size. lis habitat was wet mud above water. Two other species of mollusks, Pupilla muscornn (Linn.) and Succínea avara (Say.), both represent forestforms and suggest arrival of trees at the same time as a few grasses and mOSses. Direct­Iy on the ~urface of the clay occurs a mixture of spruce cones,needles and forest mosses. Mixed with the mosses are shells of land mollusks Succinea avara and Verligo venlricosa (Morse). One moss was peculiarly restricted to the lowest level of the forest bed. This is Bryum cyclophyllum (Schwaegr.)-a forest form that seems to have been first to establish ilself on the Two Creeks forest f100r. Other plants in this horizon repre­sented only by a few palien grains and spores are grasses, heaths, birch, Jack pine (Pinus banksiana Lamb.) and a species of Asplenium. Fungi were abundant; sorne were Beheos and athers were representative of Dema/icae. Dark beetle excavations were found on the logs and may represent two genera.

Culberson (1955), with the aid of W. C. Steere, found eight species of mosses that are associated wilh floras of more northern affinities.

Wilson ([932 and 1936) thus recorded an early phase with aquatic and semi-aquatic mollusks, an inter­mediate phase with moist to dry woodland mosses, and a final phase of f100ding with aquatic mollusks and mosses. The pollen spectra in Figure 20 by West (1961) and Schweger ([966) give additional details of the vegetational changes during Twocreokan time. See also Schweger (1969) and Maher (Geol. Soco Amer. Field Trip Guide No. 4) for additional details on other siles. The abundance of Shepherdia canadensis (buffalo berry) pollen al the base of the sediments indicates early colonization by this shrub of the land surface ex­posed by the lowering of the lake level (West, 1961). Shepherdia canadensis is a Docthem .nd moun!ain plant found in forest clearings and on sandy shores particularly in the boreal spruce forests. Thus the plant' s be­havior at the beginning of the Two Creeks interval exactly parallels ils present behavior. The phase with Shepherdia was short Iived, and Picea forest succeeded the pioneer cornmunity as indicated by the high fre­quencies of Picea palien. White spruce dominated over black spruce. The f100ding of the forest litter by the upper sills was accompanied by a large decrease in pollen frequency. At the same time the NAP total, includ­ing Ambrosia, Arlemisia and other composiles, rises slightly. This may reflect the opening out of the regional forests associated wilh the Yalders re-advance, but then there is also the possibilily that some of the palien in lbe silts is secondarily derived.

The vegetation of the Two Creeks interval is clearly boreal in character. Originally Wilson ([932) com­pared ils clima te with that of northern Minnesota today. In his later paper (1936) he suggested that the climate was not necessarily as severe as this fo! the plants also represent pioneee organisms of denuded areas under cer~n conditions and are not reliable indicators of asevere climate. West (1961) finds the interpretation of the pollen profiles from this and other nearby sites to be complicated and open to more than one interpretation. He concludes, however, that the spruce forest was able to survive along the margin of the Yalders ice, al-

95

28

though with openings. At least the climate of Two Creeks -time was not necessarily much more severe than that of today in the area. Schweger (1966 and 1969) found only simple pioneering boreal wetland species presento Roy (1964) in a study of the Pleistocene non-marine mollusca of northeast Wisconsin concluded also that these species represented climates very similar to that of northem Minnesota today.

Pollen studies of other sites of Two Creeks age in Wisconsin have also' been done by West (1960, by Sehweger (1966 and 1969), and by olhers whose work has not be en published. Sehweger (1969) found distinc­tive differenees in the flora in Ihose sites where more time was available. Local variations in the forest Iitter and maerofossils at Ihese various Two Creeks loealions al so are appearing (Blaek, Hole, Maher, and Freeman, 1965, p. 68). No vertebrate remains have been found in dated Twocreekan material s in Wisconsin yet mast­odons in deposits possibly of that age and younger are known.

Wood fragments of Twocreekan age are espeeially common in the Valderan till, but locations in eastem Wiseonsin where Twoereekan soil profiles are in situ are less common (Fig. 19). Particularly good exposures have been seen in borrow pits in the SW 1/4 and NE 1/4, SE 1/4, seco 19, T 23 N, R 19 E, Outagamie County (PieHe, 1963). Another is in the SE 1/4, NW 1/4, seco 15; T 22 N, R 15 E. Detrital organic Iitter of Two­c.,eekan age in lacustrine sediments is found at several places, such as the SE 1/4, SE 1/4, seco 22, T 24 N, R 21 E, Brown County, and the SW 1/4, SW 1/4, seco 6, T 21 N, R 23 E, in Manitowoc County. AII these sites are in borrow pits, are of very Iimited extent, and do not lend themselves to use by the public. The type sec­Hon remains unique.

The controversy of the varve-dated chronology calling for Two Creeks to be 19,000 years old (Antevs, 1962) versus the radiocarbon dales of 11,840 years (Broecker and Farrand, 1963) requires that we examine in­formation available from much of northeastern United States and Canada as well as the European transatlantie correlations. This goes far beyond the scope of this papero Suffice it to say Ihat the radiocarbon-controlled chronology has bee~ accepted by a majority of workers.

1 1

... Tr ...

" ten "t~uo~

POLlEH OIAGRAM t::I DUC1\: CRtEK IIIOGE: $ITE aye.E.$CHwtOEIt

""" "'"' 'UK"" co"'~~~::.

l l """""'" """"""

.ll IoCblDQII!au ..

. ~ • • • • POU.EN OIAGAAM Of' TYPE TWO CRUKS ay ft. o. Wl:ST

Tr,"

• PcIItn P~1of\I

PolIen spectra of Two Creeks Forest Bed (Black, Holo, Mahee, and Freeman, 1965, p. 67, Fig. 5),

Flg. 20

96

'011." $\,,,, ,. .. lO

'" lO.

". • •• "" ••

29

CI4 14000+ 1350010 13000 12000 1100010 10500 10000+ 850010 4000 DATES 14000 12500 9500

Lake Loke Lokl Two Creek Lokl Lokl Lok. Lok. Lok. EASTERN LAKES Moum •• Ar kono Whlttle .. y low water Warrtn Gtonmer. Lundy Algonquln Nlpl •• lng

Hough's Grond Rlver Two eplsodes Firsll Second I ond I 01 greol GI.n- ........ · .. -wood Chgo.oullel Hough's Thlrd downwasllng

-r-- 640 Brelt'S\ Gle'nvlood

~ drY-7--~-d---~f Volders Ihln / Glenwoo I heel

LAKE 620 -ICAGO CH

ST

\ / ?

Brelz's I , .... c. s :Ic" I ~ Columel 2 '- -,,!!.9 gh's C~'~mel

\\ J,\ Bretz's Toleslon .i Hou9,!1's Toleslon AGES_SOO

Hough's

\?I 1nlro- GI.nwood 560 low woter

I I Sub-Woyne ,

Diagrarnmatic depiction oC two contrasting interpretations of fluctuations oC water level of Glacial Lake Oticago.

YEAIlS BEFORE THE PRESENT

t bostd on C-r4<folu)

o

2,500

3,500

5,000

6,000

11,000

LAKE STAGE IN THE LAKE MrCHIGAN

8ASIN (elev_ aboye seo l.ve'l

Loke Michigon

Ch;ppewa (2301

Poyette ond / relofed stoO" 01 ~Lower A10Ol\quln~ lokes o, Stanle)' (Oepll'l "om '09

~, poIltn ploMe ItlltIC"U)

AlgonQutn (6051

Toluton (6051

Calumel (6201

Bowmonvillt (below 5601

Glenwood (6401

Fig.21

I Ook·Pone

I Pon.

1 I

JockPin.

I I

Sprue ... Fir (de<:linil'l9)

SprUCt lir

WI$CON$IN CHRONOt.OG't

XEROTHERMIC

Ooen;ng 01 Notlh Soy Oullt!

lOE RETREAT

TWO CREEK INTERSTAOIAL

CARY

Radíocarbon years. lake Ievels. forest succession, and chronology in the Lake Michigan basin (Zumberge and Potzger, 1956, Fig, 4),

Flg. 22

97

30

CONCLUSIONS AND SIGNIFICANCE

When it is recognized that the forest bed is established on lacustrine sediments and yet covered by lacus­trine sediments all of which in turn lie between two tills, something of the magnitude of the glacial history inferred becomes apparent. To this we must add slill more lacuslrine sediments and windblown materials on lop of Ihe younger til! at the Two Creeks Foresl Bed locality. This means we must take into accounl at least Ihree lakes whose levels have be.n up to a poinl more Ihan 30 feet higher than that oC present Lake Michigan. One lake followed the basal till, ooe swamped the forest bed horizon, and one carne in on top of the younger till. These f1ucluations are oC an order of magnilude beyond that which can be achieved merely by increasing preeipilation. Changes in the oullet or oullets of Lake Michigan were involved. We cannOI confine our analy­sis oC this problem only with a study of Lake Michigan. Several oC the Greal Lakes (Hough, 1958) musl be taken into accounl and their slory integrated with Ihe Pleistocene history oC Ihe St. Lawrenee, Hudson, and Mississippi river valleys. For convenience of the reader, a diagrarnmatic depiction of two contrasting ¡o ter­prelations of flucluations of waler level of Glacial Lake Chicago are recorded in Figure 21. The differences of opinion oC interpretation of field data betweeo Bretz (1959, 1964 and 1966) and of Hough (1958, 1963 and 1966) are by no means resolved. Black wDuld agree with Bretz (1966) thal s lake level at 620 feel (equal to Ihe level slong Highway 42 al Two Creeks, Fig. 5) was posl-Valders farther south, near Port Washinglon. lt seems likely thal the lake sands on the Valders lill al Two Creeks are local in occunence, bul a Calumel or olher level of Glacial Lake Chicago has nol yel been ruled oul. Discussion of Ihis problem goes beyond Ihe scope of Ihis parlicular paper and ineludes glacial lakes and drainage in oorlhero Uniled States and in Canada from Ihe Rockies to Ihe Allanlic and from Hudson Bay lo lhe Gulf of Mexico. It even involves indireclly Ihe arguments of Anlevs (1962) (cf. Hughes, 1965) on Iransallantic·conelalions and daling. Although complex, Ihe hislory of Ihe Greal Lakes is lruly a fascinaling subjecl (Hough, 1958).

Precise conelation of Ihe age of Ihe litl al Ihe base of Ihe cliff has nol been made. lt is certainly Lale Woodfordian, possibly a younger unil of Ihe Cary or subsequenl slighl re-advance such as Ihe Mankato or Porl Huroo of olher slales. The lill locally is gray bul Black has found mostly red al Ihe site. Gray drifl is sup­posealy· characlerislic of ¡he Port Huron of Michigan (Wayne and Zumberge, 1965), whereas red driCt Ihat is ·posl-Cary and pre-Two Creeh is gene rally considered representalive of the Mankalo of Minnesota (Wright and Ruhe, 1965). The Port Huron moraine (Wayne and Zumberge, 1965,p. 72) was described by Toylor (Leve re ti and Taylor, 1915, p. 293) as "one of Ihe b.l'st developed and mosl clearly defined moraines in Ihe Greal Lakes region" and Ihis slalus has been accorded Ihis moraine by every glacial geologisl who has worked in Michi­gan since thal time. The Port Huron moraine was daled by Hough (1958, p. 278) al 13,000 years ago. It was cOHelated aCross Lake Miehigan by Thwailes and Berlrand (1957, Fig. 1) with an unnamed moraine near She­boygan, Wisconsin. lf lrue, Ihen presumably Ihe Porl Huroo would extend to the norlh and encompass the Two Creeks sile. However, neIV data from Michigan disproves sorne of these findings (Farrand, Zahner, and Benninghoff, 1969). A Cary-Port Huron ¡nterstade wilh lundra plants is dated al 12,500 to 13,000 years B.P. and Hes belween Iwo red-brown sandy lills previously conelated wilh Ihe Valders.

If Ihe above conelalion is coneel Ihal Ihe basal litl al the Two Creeks Foresl Bed is of Porl Huron equivalenl, then Ihe hislory of Ihe lake sequence would begin al aboul 12,000 lo 13,000 years ago. Pollen speelra and chronology of Lake Michigao waler levels from the Michigan side are shown in Figure 22 for Ihal lime lO Ihe presenl. Stumps and olher organic maller in situ are lo be found al varíous deplhs below Ihe waler of Lake Michigan, adding lo our knowledge of Ihe low waler levels (e;g., Somers, 1968, who reporls slumps in growlh position al a deplh of 32 feel and 6,700 radiocarbon years old in Ihe Slrails of Maekinacl. Thwailes and Berlrand (1957) summarize Ihe meager informalion 00 lake levels in Ihe Two Creeks area. Obviously more delaited sludies musl be done before a elearer pielure can be obtained.

When one eonsiders Ihe magnilude of waler flucluations Ihrough hundreds of feel during ooly sorne Ihou­sands of years, Ihe presenl-day flueluations of a few feet are relatively insignifieant. Nonelheless, exeeed­ingly rapid shoreline erosion (up lo 40 feel per year al Manilowoc in 1905) (Goldlhwail, 1907), forees one lo appreciale sorne of Ihe eonsequenees of minor lake-level fluclualions. Al Ihe presenl lime, waler levels in Lake Miehigan are high after having be en ¡ow for many years. As a result, shoreline eros ion al Ihe Two Creeks Foresl Bed has been minimal unlil Ihis pasl year. When Ihe sile was firsl found by Goldlhwait and Ihen subsequently when Wilson had opporlunity lo examine Ihe loealion, waler levels also were relalively high. This pennitled shore erosion lo expose Ihe foresl bed whieh then was covered for deeades by slump and vegetation.

98

REFERENCES CITED

Alden, William C., 1918, The Quaternary geology of southeastern Wisconsin: U.S. Geol. Survey Prof. Paper 106, 356 pp.

Alden, William C., 1932, Glacial geology of the central states: XVI lnlem. Geol. Congress Guidebook 26, Excursion C-3, 54 pp.

Antevs, Erost, 1962, Transatlantic climatic agreement versus C 14 dates: Jour. Geol., v. 70, pp. 194-205. Black, Robert F., 1966, Valders glaciation in Wiseonsin and Upper Michigan-A Progress Report: Pub. 15,

Great Lakes Res. Div., Univ. of Michigan, pp. 169-175. Black, Robert F., Clark, David L., and Hendrix, Thomas E., 1968, Two Creeks Buried Forest Project - CIC

Instructional Improvement Program: Jour. Geol. Ed., v. 16, pp. 139-140.

39

Black, Robert F., Hole, Francis D., Maher, Louis J., and Freeman, Joan E., 1965, Guidebook for Field Confer­ence e - Upper Mississippi Valley: Intem. Assoc. for Quaternary Research, VJlth Congress, Nebraska Acad. Sciences, Wiseonsin portion, pp. 56-81.

Black, Robert F., and Rubin, Meyer, 1967-68, Radiocarbon dates of Wisconsin: Wis. Acad. ScL, Arts, and Letters, v. 56, pp. 99-115.

Bretz, J. Harlen, 1959, The double Calumet stage of Lake Chicago: Jour. Geol., v. 67, pp. 675-684. Bretz, J. Harlen, 1964, Correlation of glaciallake stages in the Huron-Erie and Michigan basins: Jour. Geol.,

V. 72, pp. 618-627. Bretz, J. Harlen, 1966, Correlation of glacial lake stages in the Huron-Erie and Michigan basins: Jour. Geol.,

v. 74, pp. 78-79. Broecker, Wallace S., and Farrand, William R., 1963, Radiocarbon age of the Two Creeks Forest Bed, Wiseon­

sin: Geol. Soco Amer. Bull., v. 74, pp. 795-802. Chamberlin, T. C., 1877, Quatemary Forroations - the drift: Chapo V, pp. 199-246, in Geology oi Wisconsin,

V. 2, 768 pp. Commissioners of Public Printing. Chamberlin, T. C., 1878, On the extent and significance of the Wiseonsin ketUe moraine: Wis. Acad. Sci.,

Arls, and Letters, Trans., V. 4, pp. 201-234. Chamberlin, T. C., lÍl83, Terminal moraine of the second glacial epoeh: U.S. Geol. Survey Third Annual Re­

port, pp. 291-402. Culberson, W. L., 1955, The fossil mosses of the Two Creeks Forest Bed of Wiseonsin: Amer. Midland

Naluralist, v. 54, pp. 452-459. Farrand, William, Zahner, Robert, and Benninghoff, William S., 1969, Cary-Port Huron Interstade-evidence

from a buried Bryophyte hed, Cheboygan County, Michigan: Geol. Soe. Amer., Spec. Paper 123, pp. 249-262.

Fenton, Carroll Lane, and Fenton, Mildred Adams, 1952, Gianls oi geology: Doubleday and Co., 333 pp. Frye, John C., and Willman, H. B., 1960, Classification of lhe Wiseonsinan Stage in the Lake Michigan gla­

cial lobe: Ill. State Geol. Survey Circo 285, 16 pp. Frye, John C., Willman, H. B., and Blaek, Robert F., 1965, OuUine of glacial geology of Illinois and Wiscon­

sin: The Qualemary oi Ihe Uniled Slales, H. E. Wright, Jr., and David G. Frey, editors, Princeton Univ. Press, pp. 43-61.

Frye, John C., Willman, H. B., Rubin, Meyer, and Black, Robert F., 1968, Definition of the Wisconsinan Stage: U.S. Geol. Survey Bull. 1274-E, 22 pp.

Gaenslen, George, 1969, A trip on glacial geology in the North KetUe Moraine area: Lore, v. 19, no. 3, pp. 85-97.

Goldthwait, James W., 1907, The abandoned shore lines of eastern-Wiseonsin: Wis. Geol. Survey Bull. 17, 134 pp.

Hole, Froncis D., 1967, An aneient young soil: Soil Survey Horizons, v, 8, no. 4, pp. 16-19. Hole, Francis D., and Beatty, M. T., 1968, Soils of Wisconsin, overlay map on 1:250,000 U.S. Geol. Survey

topographic quadrangles: Wis. Geol. and Na!. Hist. Survey. Hough, J. L., 1958, Geology oi Ihe Greal Lakes: Univ. Ill. Press, 313 pp. Hough, J. L., 1963, The prehistoric Great Lakes of North America: Amer. Scientist, v. 51, pp. 84-109. Hough, J. L., 1966, Correlation of glaciallake stages in the Huran-Erie and Michigan basins: Jour. Geol.,

v. 74, pp. 62-77. Hughes, O. L., 1965, Surfieial geology of part of the Coehrane district, Ontario, Canada: Geol. Soc. Amer.

Spec. Paper 84, pp. 535-565.

99

40

Lawson, P. V., 1902, Preliminary notiee of the forest beds of the Lower Fox, Wiseons,n: Nat. His/. Soco Bull., v. 2, pp. 170-173.

Lee, G. B., and Hole, F. D., 1970, Modem and buried soil profiles at the Two Creek Forest'Bed site, Mani­tOWQC County, Wisconsin: ms.

Lee, G. B., Janke, W. E., and Beaver, A. J., 1962, Partiele-size analysis of Valders drif! in eastem Wiseon­sin: Sci., v. 138, pp. 154-155.

Leverett, Frank, .nd Taylor, F. B., 1915, The Pleistocene of Indiana and Michigan and Ihe history of the Great Lakes: U.S. Geol. Survey Mon. 53, 529 pp.

Murray, R. C., 1953, The petrology of the Cary and Valders tills of northeastem Wisconsin: Amer. J. Sci., v. 251, pp. 140-155.

National Park Serviee-Wiseonsin Department of Natural Resourees, 1968, A eomprehensive plan for the Ice Age National Scientific Reserve, Wisconsin: Spec. Pub., 61 pp.

Owen, D. D., 1852, Report of a geological survey of Wisconsin, Iowa, and Minnesota: Lippincott, Grambo & Co., Philadelphia, 638 pp.

Piette, Carl R., 1963, Geology of Duck Creek Ridges, east-central Wisconsin: The Univ. of wis., M.S. thesis, 86 pp.

Prouty, C. E., 1960, Lower Paleozoic and Pleistocene stratigraphy across central Wisconsin: Mich. Basin Geol. Soc., 34 pp.

Roy, Edward C., Jr., 1964, Pleistocene non-marine Mollusca of northeastem Wisconsin: S/erkiana, no. 15, pp. 5-75.

Schweger, Charles E., 1966, Pollen analysis of lola bog and paleoecology of the Two Creeks interval: The Unív. of Wis., M.S. thesis, 41 pp.

Schweger, Charles E., 1969, Pollen analysis of Iola bog and paleoecology of!he Two Creeks Forest Bed, Wis­consin: Ecology, v. 50, pp. 859-868.

Soil Survey Slaff, 1960, Soil classification, a comprehensive system, 7th approximation: U.S. Dept. of Agricul­ture, Govemment' Printing Office, 265 pp.

Soil Survey Staff, 1967, Supplement to soi! classification system: U.S. Dept. of Agriculture, Govemmen! Printing Office, 207 pp.

Somers, Lee H., 1968, A research dive in the Great Lakes: Umnos, v. 1, no. 2, pp. 2-5. Sultner, Lee J., 1963, Geology of Brillion Ridge, east-central Wisconsin: The Univ. of Wis., M.S. thesis,

99 pp. Thwaites, F. T., 1943, Pleistocene of part of northeastem Wiseonsin: Oeol. Soco Amer. Bull., v. 54, pp.

87-144. Thwaites, F. T., 1953, Field guide, Friends of the Pleistocene: Mimeo, 26 pp. Thwaites, F. T., and Bertrand, Kenneth, 1957, Pleistocene geology of the Door Peninsula, Wisconsin: Oeol.

Soco Amer. Bull., v. 68, pp. 831-880. Wayoe, William J., and Zumberge, James H., 1965, Pleistocene geology of Indiana and Michigan: in Qua/er­

nary of the Uni/ed Sta tes, Princeton Univ. Press, pp. 63-84. West, R. G., 1961, Late- and postglacial vegetational history in Wisconsin, particularly changes associated

with the Valders readvance: Amer. Jour. Sci., v. 259, pp. 766-783. White, George W., 1964, Early description and explanation of kettle holes: Jour. Olac., v. 5, pp. 119-122. Whittlesey, Charles, 1860, On the drift cavities, or "potash kettles" of Wisconsin: Amer. Assoc. Advance­

ment ScL, Proc., 13th meeting, 1859, pp. 297-301. Whittlesey, Charles, 1866, On the fresh-water glacial drift of the northwestern states: Smithsonian Con/ro

Knowledge, No. 197, 32 pp. Wilson, L. R., 1932, The Two Creeks Forest Bed, Mimitowoc County, Wisconsin: Wis. Acad. Sci., Arts and

Letters Trans., v. 27, pp. 31-46. Wilson, L. R., 1936, Further fossil studies of the Two Creeks Forest Bed, Manitowoc County, Wisconsin:

Torrey Bo/. Club Bull., v. 66, pp. 317-325. Wright, H. E., Jr., and Ruhe, R. V., 1965, Glaciation of Minnesota and Iowa: in Qua/emary of /he United

Sta/es, Princeton Uni;". Press, pp. 29-41. Zumberge, James H., and Potzger, John E., 1956, Late Wisconsin chronology of !he Lake Michigan basin cor­

related with poli en slUdies: Oeol. Soco Amer. Bull., v. 67, pp. 271-288.

100

Geological Society oC America Special Paper 251

1990

Radiocarbon confirmation of the Greatlakean age oi the type Two Rivers till of eastern Wisconsin

Allan F. Sehneider Department 01 Geology, Uni~ersity 01 Wisconsin-Parkside, Kenosha, Wisconsin 53141

ABSTRACf

Three radiocarbon dales on wood, including one on a 10g from Ihe Iype seellon of Ibe Two Riyers till, show Ihal Ihe age of Ihis liU unil is unqueslionably Greallakean (post-Twocreekan).

The Two Rivers liII, now formally designaled Ihe "Two Riyers Member of Ihe Kewaunee Formation," was named in 1973 by Eyenson for flne-grained reddlsh-brown 1m found along Ihe Lake Miehigan shore north of Two' Rivers, Wiseonsln. The 1m was eorrelaled wllh tiII of similar Ulhology Ihal oyerlles Ihe Two Creeks Foresl Bed al Ihe Two Creeks type seetlon, and Ihus Ihe till was eonsldered posl-Twoereekan (Greal­lakean) in age. Unlike Ihe age oflhe Valders liU, whlch has been hotly debaled (whelher pre-Twocreekan or posl-Twocreekan) during Ihe pasl 15 years, Ihe age of Ihe Two Riyers liII has nol been Ihe subjecl of direcl conlroversy. However, Ihe age of Ihe Two .Rivers liU al lis type locality has nol prevlously been demonslraled by radiometrlcally . daled malerial.

Part of a large log enclosed in tlU was colleeled from Ihe Two Riyers Iype seclion In 1968, aboul Ibree years before Evenson began his invesligalions in Ihe Twin Rivers lowland, bul Ihe exlslence of Ihls sample remalned generaUy unknown. The wood has now been daled al 11,910 ± 120 yr B.P. (ISGS-I058), Ihus proying Ihal Ihe 1m is younger Ihan Ihe Two Creeks Forest Bed from which Ihe log musl have been derived by ~~ .

Two addilional dales, from asile on Ihe soulh slde of Kewaunee, also serve as eonflrmlng dales for Ihe Greallakean age of Ihe Two Rivers liII. Wood from a blaek, snall-rieh peal layer has been daled al 11,700 ± 110 (ISGS-I061) and 11,650 ± 170 (ISGS-I234) yr B.P. The organie layer underlies flne-grained reddlsh-brown 1m Ihal has been eorrelaled with similar liU Ihal overlles Ihe Two Creeks Foresl Bed al ils Iype seclion and Ihus was calIed Two Rivers tiII by Aeomb and olhers (1982).

INTRODUCTlON

The fine-grained reddish-brown till units of eastem Wiscon­sin, commonly caUed the red c1ayey tills, have long been the subject of study and debate. Initially interpreted by Chamberlln (1877) as laeustrine sediment, the "Red Clay" was later correctly identified as till by Alden (1906, 1918) and other workers.

During the past 15 years, controversy over the red tills has focused mainly on the distribution, age, and correlation of the Valders till ofThwaites (1 943)-more specifically, whether that till is pre-Twocreekan or post-Twocreekan in age. Consideration of the age of the Valders tiIl, however, necessarily involves con-

sideration of other red till units, particularly the Two Rivers till of Evenson (1973a, b), whieh was regarded by Thwaites and Ber­trand (1957) to be part of the Valders till. The details of the debate conceming the age and correlation of the Valders and Two Rivers tills need not be reviewed here, inasmueh as those details haye been summarized weU in a number of fairly recent publlcations (e.g., see Blaek, 1980; and Acomb and others, 1982).

The purpose of this ehapter is to consider three radiocarbon dates on wood samples from eastem Wisconsin that demonstrate !he age of the Two Rivers till to be unquestionably Great-

Schneider, A. F., 1990, Radiocarbon confirmation oCthe Greatlakean age oCthe type Two Rivers till of eastem Wisconsin, In Schneider, A. F., and Fraser, G. S" eds" Late Quatemary hislory oC the Lake Micbigan basin: Boulder, Colorado, Geological Society of America Special Paper 25(,

101

52 A. F. Schneider

lakean-that is, post-Twocreekan. Two of these dates have beeo cursorily reported elsewhere (Sehneider, 1984; Liu and others, 1986, p. 131). One ofthe dated samples was collecled from Ihe type section of the Two Rivers till, and lhe resultant date repre­sents the fírst and only radiometric dale on material from the Two Rivers type locality.

RECOGNITION AND CORRELATION OF THE TWO RIVERS TILL

The name "Two Riveis till" was proposed by Evenson (1973a, b) for fine-grained reddish-brown till found along the Lake Michigan shoreline north ofTwo Rivers, Wisconsin (Fig. 1). More recently, the unil has been accorded formal stratigraphic rank as the "Two Rivers Member of the Kewaunee Formatioo" (Mickelson and others, 1984). The Kewaunee Formation com­prises all red clayey till units of eastem Wisconsin (Fig. 2); be­sides the Two Rivers Member, it ineludes three additional Lake Michigan Lobe deposits-the Ozaukee Member, lhe Haven Member, and the Valders Member (Mickelson and others, 1984).

For the Iype locality of the Two Rivers till, Evenson desig­nated a sand pit on Ihe east side oC Wisconsin Highway 42 at

LAKé

MICHIGAN

1. Map of part of east-central Wisconsin showing localities distribution of units. Modified from Mickelson and Evenson (1975,

Fig. 1); area of Yalders till (ooarse stippled pattem) and Yalders tilllimit frOID Acomb (1978, Fig. 6).

GREEN eA y Lose LAKE MICHIGAN loeE

WEST SIOE EAST SIOE

MlODLE INLET GlENMORE TWO RIVERS MEMBER MEMBER MEMSER

KEWAUNEE YALOE.RS MEMBER KIRBY LAKE CHllTON

FORMATION MEM6ER . ....eMBER HAVEN MEMBER

SllVER ClIFF BAANCH RlVER MEMBER MEMBER OZAUKEE MEMBER

Figure 2. Red clayey till units of eastem Wisconsin. Not shown is the new1y defined Florence Member, which occurs beneath the Silver Cliff Member on the west side ofthe Green Bay Lobe (Clayton, 1988). The Two Creeks bed, whicb occurs between members oC the Kewaunee Formation, is not recognized as a formal lithoStratigraphic unit of the formation (Mickelson and others, 1984).

the north edge of the city of Two Rivers (Evenson, 19733, p. 2289-2290, 2296; 1973b, p. 16-18, 22). The till was correlated with till of similar lithology tha! overlies the Two Creeks Forest Hed at the Two Creeks type section 18 km north oC Two Rivers (Fig. 3), and thus lhe Two Rivers till was considered to be póst-Twocreekao or Greatlakean (Evenson and others, 1976) in age. Correlation of the red till at Two Rivers with that al Two Creeks was subsequently supported by the investigalions of Mickelson and Evenson (1975) and Acomb (1978; Aeomb and others, 1982).

Al its type section lhe Two Rivers till sharply overlies lacus­trine sands (Figs. 3 arid 4), whieh Evenson (1973a, b) interpreted as deposits of the Gleñwood phase of glacial Lake Chicago. A water well drilled at the site showed the sand to be 9 m thiek and to overlie 25 m of another red·till unit that rests on bedrock, Hecause the Glenwood phase is clearly pre-Twocreekan in age, as demonstrated by Eschman and Farrand (1970) in Michigan .nd by ~chneider and Reshkin (1970) in Indiana, the lower red lill al Two Rivers must also be pre-Twocreekan. Evenson correlated this lower red till with the till below the forest bed at the Two Creeks type section and with the red Valders till of Thwaites (1943; Thwaites and Rertrand, 1957) at its type locality (Fig, 3).

More recently, however, Aeomb (1978; Acomb and others, 1982) identified two additional pre-Twocreekan Lake Michigan Lobe red-till units (Fig. 2): the Ozaukee and Haven Members of the Kewaunee Formation (Mickelson and others, 1984), both of whieh he believes are older Ihan the Valders till. The lower till al both the Two Rivers and Two Creeks type seetions is considered by Acomb to be part oC the Haven Member, and the Valders till is believed to be .bsent al both these localities. In any event, both the Ha ven and Valders tills are considered to be pre-Twocreekan oc late Woodfordian in age, and the Two Rivers till is correlated as post-Twocreekan or Greatlakean. Black (1974, 1978, 1980), on the other hand, argued that the red till at Valders is post­Twocreekan in age and correlated it with the upper red till al both Two Creeks and Two Rivers. Until Blaek's untime1y death in 1983, the controversy between Blaek and the Evenson­Mickelson group over the age of the type Yalders till had eon­tinued almost unabated for a full decade.

102

Greatlakean age 01 the type Two Rivers till S3

Valders Two Rivers Two Creeks Manitowoc R.

Type Locality Type Locality Type Locality K o m e $

I ... oi e e

'-l l .... .... I

o ~. Y."~ ~ " ,,0000" • • • • 'c'" .. " .. " c " " " "" w /.; ~ R d T' I l' ',,"" ~,J ,J Fa' e $ I . I~ .;.,' e ,,' " .J " • "~o 00"" " " .~ :', Gro y Ti II .- - .- . -,:.', '::-·1 r· l'o k e .:" B e d $' . ''-

Sed • • : : ~ ':' "! .' . ': 0: " ,": ~ ." -: R e d () o " -" ... :" .. " "O..l "00 0.J "" .. .,°. 0 lake ?~. ~ ","" "", T ¡ I I level

, .. ,oo··"Q"ooo"o".>oo" .. "J ... . ? . "!-.4.-_o" ~~.?.L

Figure 3. Diagrammatic cross section from Valders type locality to Two Rivers type locality to Two Creeks type locality. Not to seale. Slightly modified from Evenson (1973a, Fig. 6).

AGE OF THE TWO RIVERS TILL

Unlike the age orthe Valders till, the age ofthe Two Rivers lill has not been the subjeet of direet controversy. Consideration of its age, however, is obviously inseparable from the question of the age and correlation of the Valders tillo Neither the age of the Valders Member nor the age of the Two Rivers Member al their respective type localities has been demonstrated previously by radiometrically dated material.

Two Rivers site

In July of 1968, abou! three years before Evenson began his investigations in eastero Wisconsin, the site later designated by Evenson as the type locality ofhis Two Rivers till was visited by a geography class from the University of Wisconsin-Milwaukee, Part of a moderately large log completely enclosed in till (Fig. 5) was observed, photographed, and colleeted bymembers of the class at that time.

Knowledge ofthis wood sample remained Iimited, however. In 1982 I learoed about the log and obtained it from Paul Stoel­ting of Carthage College, who as a graduate studenl was involved in its colleetion 14 years earlier. Part of the log was submitted to the radiocarbon laboratory of the Illinois State Geological Survey and dated at 11,910 ± 120 yr B.P. (ISGS-1058; Liu and others, 1986, p. 131). The wood, therefore, is unquestionably Two Creeks wood, inasmuch as the accepted average age of the Two Creeks Forest Bed is 11,850 ± 100 radiocarbon years (Broecker and Farrand, 1963). Thus the Two Rivers till at its type locality is younger than the Two Creeks Forest Bed, from which the log must have been derived by Ihe ice. The date aIso confirrns that the correlation of the red till aboye the laeustrine sands at Two Rivers with the red till aboye the forest bed at Two Creeks is indeed corree!.

103

Because the size and eonfiguration of the Two Rivers pil have ehanged through the years, it is diffieult to determine the exaet location of the log within the outline of the present excava­tion. Stoelting and I are confident, however, that the wood was taken from the north wall of the pit, probably about 25 to 35 m east 'of the spot photographed and diagrammed by Evenson (1973a, Fig. 5, p. 2290; 1973b, Fig. 5, p. 17) to show the relation between red clayey Two Rivers till and deformed ice-shoved Glenwood laeustrine sediments.

Kewaunee site

Two radiocarbon ages have been deterrnined on wood samples from the type section of the Kewaunee Formation (Mickelson and oth~rs, 1984), located along the Lake Michigan

Figure 4. Photograpb sbowing Two Rivers till overlying lae",trine sand at the Two Rivers type locality, Two Rivers, Wisconsin. Pboto taken June, 1979.

54 A. F. Schneider

Figure 5. Photograph showing dated log in Two Rivers till at the Two Rivers type locality. Photo courtesy orPaul Stoelting; taken July, 1968.

shore at Ihe south edge of the city of Kewaunee, about 14 km (8.7 mi) north of the Two Creeks type section and 32 km (20 mi) north of the Two Rivers type section (Fig. 1).

Fine-grained reddish-brown lilI at the top of Ihe Kewaunee seclion 30 m' aboye lake level was correlaled with the reddish­brown lill Ihal overlies the Two Creeks Forest Bed at ils type locality by Acomb (1978) and Acomb and others (1982) and thus called Two Rivers tUl. The till is underlain by a blaek, snaU-rieh organie layer, mostly peat, that ranges from 5 to 13 cm thick (Fig. 6). Barry Miller of Kent State University has studied the snaíl fauna, and the beetle population has been analyzed by Clarke Garry and Donald Schwert. The fauna and paleoenviron­menl of the site are considered in a companion paper (Garry and others, this volume).

Wood from the top oC the arganic layer al the Kewaunee site thal 1 eollected in 1981 was dated by the l11inois State Geo­logical Survey lab al 11,700 ± 110 yr B.P. (ISGS-I061; Líu and others, 1986, p. 131). A second wood sample collected from the organie layer by Professors Garry and Baker in 1983 yielded a similar age oC 11,650 ± 170 yr B.P. (ISGS-1234; Garry and others, this volume). Both dates are considered to be late Two. ereekan dates. Thus the overlying red clayey till must be post­Twocreekan (Greatlakean) in age, as previously correlated by Acomb.

The radiocarbon <!Jites from Ihe Kewaunee site call attention lo Ihe several dates on organic-rich lake sedimenls from cores taken in 1970 from nearby Seidel Lake by H. E. Wright, Jr. Seidel Lake is a tiny lake thal occupies an enclosed depression on the Two Rivers till surfaee less than 2 km wesl of the Kewaunee site. The younger Seidel Lake dates (Bender and others, 1975, p. 131) are generally compatible with the new dates from the Kewaunee bluff site, with the possible exeeption of the

104

11,620 ± 110-yr B.P. date (WIS-641), which appears to'be some­what too old (although nol inconsisten!) for a post-Two Rivers date by comparison with the pre-Two Rivers (1:wocreekan) dates from the Kewaunee site. A previously deterrnined date of 12,360 ± 125 yr B.P. (WIS-462; Bender and olhers, 1971, p. 480) rrom Seidel Lake was acknow1edged to be inconsisten! with the identificalion of the enclosing till.

CONCLUSION

Radiocarbon dates from Ihe Two ~ivers and Kewaunee sites firmly establish the age oC the Two Rivers till as post­Twocreekan or Greatlakean. Thus, it is the age of Ihe Valders lill Ihat musl now be demonstrated by radiometric dates, in order lo determine whether it correlates with the Two Rivers till, as Blaek contended, or is indeed pre-Twocreekan (late Woodfordian) as held by the Evenson-Mickelson group. The evidenee at this lime strongly Cavors Ihe latter inlerpretalion. Unless and unli! sueh time as datable organie material is found in Ihe Valders till al ils type locality, however, sorne question as to the age oC this red-till unit will remain.

, Figure 6. Pholograph ofTwocreekan organic layer beneath Two Rivers till at Kewaunee, Wisconsin. Wood twig in upper lertjust below contac! was dated al 11,700 ± 110 yr R.P. (ISGS-1061). Light-colored spots in organic layer are mollusc shells. Pholo taken July, 1981.

ACKNOWLEDGMENTS

1 thank Paul Stoelting, now al The University oC Wisconsin­LaCrosse, Cor supplying the log from the Two Rivers site and also for photographs taken when the log was collected. The Illinois State Geological Survey deterrnined the radiocarbon age oC the log and also dated the wood samples from the Kewaunee sile. The manuseript was reviewed by E. B. Evenson, R. C. Flemal, and W. N. Melhom.

Greal/akean age ollhe type Two Rivers liIl 55

REFERENCES ClTED

Acomb, L. J., 1978, Stratigraphic relations and extent ofWisconsin's Lake Mich· igan Llbe red t.ms[M.s. thes~t. Madison, University ofWisoonsin-Madison. 68 p.

Acomb, L. J., Mickelson, D. M.o and Evenson, E. B., 1982, Ti1Istratigraphy and late glacial eveRts in tbe Lake Michigan Lobe oC eastem Wisconsin: Geologí­cal Society oC Amena Bulletin, v. 93, p. 289-296.

Alden, W. C" 1906, Description oC tbe Milwaukee Quadrangle, WLsconsin: U.S. Geological Survey Geological Atlas, Folio 140, 12 p.

- I 1918, The Qualemary geology oCsoutheastem Wisconsin: U.S. Geological Survey Professional Paper 106, 356 p.

Bender, M. M" Bryson, R. A., and Baerreis, D. A., 1971, University ofWi.sconsin radiocarbon dates IX: Radiocarbon, v. 13, p. 475-486.

-- • 1975, University ofWisconsin radiocarbon dates XII: Radiocarbon, v. 17, p.121-134.

Black, R. F., 1974, Late Pleistocene shoretines and stratigraphic relations in the Lake Michigan basin; Discussion: Oeological Soclety oC America Bulletin, v. 85, p. 659-660.

-- , 1978, Comment on 'Oreatlakean Substage; A replacement Cor Valderan Substage in the Lake Michigan basin' by Evenson, E. 8., and olhers: Quater­nary Research, v. 9, p. 119-123.

-- , 1980, Valders-Two Creeks, Wisconsin, revisited; The Valders liII is masl likely ~t-Twocreekan~ Geological Society oC America Bulletin, Part 1, v. 91, p. 713-723.

Broecker, W. S., and Farrand, W. R., 1963, Radiocarbon ageoClheTwo Creeks Forest Sed, Wisconsin: Geological Society oC America Bullelin, v. 74, p.795-802.

Chamberlin, T. C., 1877, Geology oC easlem Wisconsin, ln Geology oC Wiscon­sin, Survey oC 1873-1871: Wisconsin Geological Survey, v. 2, p. 91-405.

Oayton, L., 1988, Florence Member oClhe Kewaunee Formation, in Anig, J. W., Clayton; L., and Mickelson, D. M., 005." Pleistocene stratigraphic units 'oC Wisconsin, 1984-1987: Wisconsin Geological and Natural History Survey InConnation Circular 62, p. 57-59.

Eschman, D. F., and Farrand, W. R., 1970, Glacial history oC the glacial Grand Valley, In Guide Book Cor field trips; Nortb-Central Section, Geological

Society oC America meeting, Eas! lansing, Michigan: Michigan Basin Oeo­logical Sociely, p. 131-157.

Evenson, E. 8., 1973a, late Pleistocene sborelines and stratigrapbic relations in tbe Lake Michigan basin: Geological Society oC America BuUelin, v. 84, p.2281-2298.

- , 1973b, A reevaluation oCtbe "Valders" limitin Ibe lake Michigan basin, In Evenson, E. 8., Eschman, D. F., and Farrand, W. R, The "Valderan" probtem, Lake Michigan basin, 22nd Annual Midwest Friends oC the Pleis­locene Field ConCerenre Guidebook: Ann Arbor, Micbigan, Midwest Friends oC the Pleistocene, 29 p.

Evenson, E. B., Farrand, W. R., Mickelson, D. M., q.chman, D. F., and Maher, L. J., 1976, Greatlakeal.1 Subslage; A replacement Cor Valderan Substage in tbe Lake Micbigan basin: Quatemary Research, v. 6, p. 411-424.

Liu, C.-L., Riley, K. M., and Coleman, D. D., 1986, Dlinois State Oeological Survey radiocarbon dates IX: Radiocarbon, v. 28, p. 110--133.

Mickelson, D. M., and Evenson, E. B., 1975, Pre-Twocreekan age oC the type Valders till, Wisconsin: Geotogy, v. 3, p. 587-590.

Mickel.son, D. M., Clayton, L., Baker, R. W., Mode, W. N., and Schneider, A. F., 1984, Pleistocene stratigrapbic unils oC Wisconsin: Wisconsin Geological and Natural History Survey Mi.scellaneous Paper 84-1, 97 p.

Schneider, A. F., 1984, Radiocarbon confirmation oC Ibe Greatlakean age oC the Iype Two Rivers till or eastem Wisconsin: Geological Society oC America Abslrac~ wilh Programs, v. 16, p. 193.

Schneider, A. F., and Resbkin, M., 1970, Age and correlation oC the Glenwood stage oC glacial Lake Chicago: Geological Society oC America Abslracts with Programs, v. 2, p. 404.

Thwaites, F. T., 1943, Pleistocene oC part oC northeastem Wisconsin: Oeological Society oC America Bulletin, v. 54, p. 87-144.

Thwaites, F. T., and Bertrand, K., 1957, Pleistocene geology oC the Door Penin­sula, Wiscons.in: Geological Society oC America Bullelin, v. 68, p. 831-879.

• MANUSCRIPT ACCEPTED BY TItE SocIETY QcrOBER 9, 1989

105

Printtd in U.S.A.

106

Geological Society oC America Special Pape, 251

1990

Environmental analysis of a Twocreekan-aged beetle (Coleoptera) assemblage from Kewaunee, Wisconsin

C1arke E. Garry Departmenl 01 Bi%gy, University 01 Wisconsin-River Fa/Is, River Fal/s, Wisconsin 54022 Robert W. Daker Departmenl al Planl and Earth Science, University al Wisconsin-River Fa/Is, River Fa//s, Wisconsin 54,022 Donald P. Schwert Departmenl al Ge%gy, North Dakola Slale University, Fargo, North Dakola 58105 Allan F. Scboeider DepartmenloIGe%gy, University al Wisconsin-ParkSide, Kenosha, Wisconsin 53141

ABSTRACf

A Twocreekan organic horlzon, which ls underlaln by till of Ihe Haven Member and overlaln by liU of Ihe Two Rivers Member of Ihe Kewaunee Formalion, was investlgaled near Kewaunee, Wlsconsin. Wood from Ihls horlzon was daled al 11,700 ± 110 D.P. (lSGS-I061) and 11,650 ± 170 D.P. (ISGS-I234). The ioseel fauna from Ihe Kewaunee sile has many elemenls in common wlth Ihe insecls from Ihe type sectlon of Ihe Two Creeks Forest Bcd, 14 km lo the soulh. These inelude Ihe northwestem carabid Asaphidion yukonense, northem carabids Carabus laedalus and Bembidion grapi~ and Ihe northem staphylhúd Acidola quadrata. In eonlrast, Ihe Kewaunee site fauna appears to hine inhabited a somewhal colder environmenl, as suggesled by Ihe oceur­renee of Ihe carabids Cymindis unicolor and Pterostichus (Cryobius) spp. We inlerpret Ibe Kewaunee speclmens of aquatle, waler-marginal, and upland species lo represenl an aIIochthonous rather Ihan an autochthonous assemblage.

INTRODUCfION

Virtuallyall knowledge regarding the Twocreekan paleoen­vironment of the western Lake Michigan basin has been derived from extensive studies of the type locaIity of !he Two Creeks Forest Bcd (Fig. 1), located approximately at the border of Ke­waunee and Manitowoc Counties, Wisconsin, between Seco 35,T.22N.,R.24E. and Sec.2,T.2IN.,R.24E. (44°19'30"N, 87°32'36"W). The average radiocarbon date on wood from the fores! bed is 11,850 D.P. (Broecker and Farrand, 1963; Morgan and Morgan, 1979); these dates have becn used to establish the chronology of Ihe northward recession of ice in the Lake Michi­gan basin associated with the Twocreekan Substage (Evenson and others, 1976).

The type locality of the Two Creeks Fores! Bed has gener­ated considerable interest in the late-glacial history of the Lake

Michigan basin. Goldthwait (1907) recognized that red tills He stratigraphically aboye and below the forest bed and interpreted !he sequence as recording more than one glacial advance. Later, the upper red till was corcelated with the red surface till at Valders, Wisconsin (Bretz, 1951; Thwaites and Bertrand, 1957; Frey and others, 1968; B1ack, 1970, 1980), suggesting a major post-Twocreekan readvance. Evenson (19733, b) was the first to suggest that this corcelation was erconeous. He argued that the surface tm at Valders corcelated with the lower red till at Two Creeks and the upper red till represented a significantiy less exten­sive readvance than previously believed. This view has becn sup­ported by subsequent studies in the central Great Lakes region (Evenson and Mickelson, 1974; Mickelson and Evenson, 1975; Evenson and others, 1976; Evenson and Dreimanis, 1976; Far-

Garry, C. B" Baker, R. W., Scbwert. D. P" and Scbneider, A. F., 1990, Environmental analysis or a Twocreekan-aged beetle (Coleoptera) a.ssemblage rrom Kewaunee, Wisconsin, in Schneider, A. F., and Fraser, G. S., eds., late Quatemary history or tbe Lake Michigan basin: Boulder, Colorado, Geological Society oC America Special Paper 251.

107

58 C. E. Garry and Olhers

Manitowoc

I 10ml I 16km

Figure l. Map showing the location of the Kewaunee site in relation to . the type section of the Two Creeks Forest Bed.

rand, 1976; Acomb and others, 1982; Miekelson and olhers, 1983).

In Ihis ehapler, we describe aD organie horizon of Two­ereekan age al Kewaunee, Wisconsio, and compare ils inseet remains lo Ihose previously described from Ihe Two Creeks Iype seelion 14 km lo Ihe soulh (Fig. 1).

PREVlOUS STUDIES

Sludies of Ihe pollen and planl remains of Ihe Two Creeks Foresl Bed were initiated by Goldlhwail (1907, p. 61), who described !he preseoce of a "conspicuous bed of peal, stieks, logs, and large Iree lrunks, whieh unmistakably represenls a glacialed forest." Cheoey (1930,1931), Wilson (1932,1936), and Culber­son (1955) described 23 species of mosses allogelher, mosl of whieh were associaled with floras of more northem affinities. In addition lo mosses, Wilson (1932, 1936) idenlified macrofossils of bolh blaek spruce (Picea mariana) and white spruce (P. glauca).

The firsl detailed palynologie analyses of Ihe Two Creeks Foresl Bed localily were condueled by Wesl (1961). He found Ihal spruce made up 80 lo 90 percenl of Ihe lotal pollen conlenl, wilh Ihe pollen of while spruce far exceeding Ihal ofblaek spruce. He coneluded Ihal Ihe flora was elearly boreal in eharaeler.

Sludies of Ihe invertebrale remains associaled with Ihe planls al Ihe Iype localily have cenlered primarily 00 molluscs and iosecls. Eighl species of molluscs described by Wilson (1932) from Ihe forest bed were primarily oorthern forms. Morgan and Morgan (1979) ideolified a fauna of 49 taxa (21 species) of beetles (Coleoplera). The fauoa ineluded six species of bark bee­tles (Scolytidae), nearly al1 of whieh are associaled wilb spruce. They inlerpreled Ihis "reslrieled" assemblage as haviog accumu­laled in situ aod as represeoling a dry boreal foresl eoviroomenl wilh sorne opeoings and a sparsely vegetaled grouod suñace.

LOCATION, STRATIGRAPHY, AND AGE OF THE KEWAUNEE SECTION

Our study seelion (Fig. 1) is localed along Ihe shoreline of Lake Miehigan 00 a 30-m bluff al Ihe soulh edge of Kewauoee, Wisconsin (NE\4SEIJ<8E\4,Sec.19,T.23N.,R.25E., Kewauoee 7.5-min Quadrangle; 44"26'49"N., 87°30'8"W.). The stratigraphy of!he sile is described in Table I aod iIIuslrated in Figure 2.

Two radiocarbon dales were obtained on wood from Ihe Kewauoee sile: 11,700 ± 110 B.P. (ISGS-I061) and 11,650 ± 170 B.P. (ISGS-1234). These dales compare favorably wilh Ihose from Ihe Two Creeks Foresl Bed reported by Broecker and Far­rand (1963), wilh ao average radiocarbon dale of 11,850 B.P., and by Morgán and Morgao (1979), with dales of 11,810 ± lOO B.P. (GSC-2166) and 11,860 ± 110 B.P. (WAT-57) .

MEmODS

Malrix partiele-size analyses for all uoils were made using Ihe bydromeler melhod (Blaek, 1965) wilh measuremeols given io U.S.D.A. partiele size elasses and q, unils [sand = 2.0 lo 0.05 mm (-1.0 lo 4.25 q,), silt = 0.05 lo 0.002, mm (4.25 lo 9.0 q,), and elay <0.002 mm «9.0 q,)]. Clay-mineral delerminalions were made by H. D. Glass of Ihe lIlinois Stale Geological Survey. . A lotal of 64 kg of sedimenl was col!eeled in bulk for inseet analyses from Ihe orgaoie horizon. Chilinous remains were ex­lraeled from Ihe organics followiog a lechnique described by Schwert and Morgan (1980). Bulk samples were lirsl washed Ihrough a 52-mesh (300-l'm) sieve lo remove Ihe silt and elay fraelioos. The residue was subjecled lo a kerosene flotalioo lo concenlrale Ihe insecl remains. The parts were mouoled wilh gum tragacanlb onlo mieropaleonlological slides. As al! of Ihe species represenled appear lo be extanl, identilicalions were made using the modem reference colleclions of Ihe Geology Depart­ment and Ihe Stale Insect Col!eclion, bolh al North Dakota Stale Universily. The fossils have been deposiled in the colleclioo oí Ihe Departmen! of Biology, Universily of Wisconsin-River Falls.

DESCRIPTION OF mE FAUNA

Among Ihe ehitioous remains exlraeled are oslracods, ela­doceran ephippia, spiders, and oribalid miles. Additionally, al leasl six orders of inseels, ineluding Hemiplera (Pentalomidae,

108

AlUllyses 01 a Twocreekan-aged beetle assemb/age 59

Saldidae), Homoptera (Cicadellidae), Coleoptera (17 families), Triehoptera, Diptera (Chironomidae), and Hymenoptera (For­micidae) were present. The insects are dominated by Coleoptera; over 600 beetle individuals representing 59 taxa have been identi­fied (Table 2)_ AIso present in the horizon were six species of aquatie molluscs, including Stagnico/a elodes, Fossaria obrussa, Gyraulus ef_ parvus, G. er. deflectus, G. ef. altissimus, and Pis­Idium casertanum, and one terrestrial taxon, Vertigo spp. (B. B. Miller, written communication, 1983).

STRATIGRAPHIC UNIT

DEPTH PARTICLE SIZE %

o 25 50 75 100

ela)' 5111 Sond

2 Both the sediments and inseet fauna evidently accumulated

in a shallow body of water. That this water was in part open is apparent rrom the presence of sueh aquatic beetles as Dytiseus, Colymbetes, agabine dytiscids, and at least one gyrinid (Fig. 3f). The local presence of marshy rones of sedges or grasses is indi­cated by the chrysomelids Donada and P/ateumaris (Fig. 3g), as well as by omaliine staphylinids and two species of the carabid Elaphrus. These zones were in part bordered by open, probably sandy patches that supported heterocerids, scarabs (Aegialia), carabids (Bembidion sordidum, B. grapii (grapei), and Dyschi­rius spp.), staphylinids (Stenus and Bledius), and byrrhids. Indi­cators of drier upland habitats are also present in the assemblage. These inelude the carabids Carabus taedatus, Pterostichus (Cry­obius) spp., Pterostichus adstrictus, Cymindis unicolor, Notiophi­fus sp., and Miscodera aretica.

TWO RIVERS MEMBER 111111

ORGANIC SEDIMENT __ _

BEACH GRAVEL

HAVEN MEMBER

11/111

3

4

5

6

7

Figure 2. Stratigraphy ofthe Kewaunee Formation at the Kewaunee site.

TABLE 1. SECTlON DESCRIPTlON OF THE KEWAUNEE FORMATlON AT THE KEWAUNEE SITE'

Unit Deplh (m)

Two Rlvers Member (till) 0.00-3.66

Organle Sediment 3.66-4.33

Beacll Gravel 4.33-5.70

Haven Member (till) 5.7+

• Deseription

Cslcareous, Ioam-texrurad till averaglng 43.7 pereent sand, 31.3 pereent silt, and 25 pereent e/ay. Modem solum lo deplh 010.4 m wllh leaehing to deplh 01 0.55 m. Cólor vartes Irom light reddish brown (5YR 6/4) In wealhered zona to reddish brown (5YR 4/4) in unwealhered state to dark brown (7.5YR 4/4) near base. Pebbly, cantalnlng numerous dolomite elasts as well as Igneous e/asts 01 rhyolite porphyry. Matrix e/ay-mineral content averages 60.5 pereent iIIite. 16.5 pereent kaalinite plus chlorite, and 23 percent expandables. lower 0.3 m contains numerous iron-oxide stre.ks, discontinuous /enses 01 dark graylsh brown (10YR 4/2) organie-rleh Ioam, and lewer pebb/e-sizad elasts. Abrupt lower boundary.

S~ong/y calcareous very dark gray (10YR 311) silt 108m averaging 30 pereent sand, 61 pereent sllt, and 9 percant elay. Conta/ns abundant wood Iragments, mol/uses, and insects. Interpreted to be shallow-watar lacustrine In origino

S~ong/y calcaraous, very gravelly sandy 108m averaging 58.5 pereent sand, 31.8 percant silt, and 9.7 pareent e/ay. Colorvarles Irom dark yellowish brown (10YR 4/4) to dark brown (7.5YR 4/4). Contalns many angular to suban guiar pebblas and Is inlerpretad to be be.eh or shallow lacustrine In origln. Lower contact abrupt.

S~ongly calcaraous Ioam-textured till avaraging 39.0 pereent sand, 31.4 pereent silt, and 29.4 percant e/ay. Matrix color varles Irom dark yaUowish brown (10YR 4/4) near top to pinkish gray (5YR 7/2) wilh depth. Clay-mineral content averages 54.0 pereent iIIite, 20 pereent kaolinite plus cIllorlte, and 26 pereent expendables. Total thickness undeterminad due to poor exposura.

'Elevatlon 01 upper surfaca approximate/y 204 m.

109

110

EUROPE LAKE SEDIMENT CORES AND VEGETATION IDSTORY

William N. Mode Department of Geology

University of Wisconsin-Oshkosh Oshkosh, Wisconsin 54901

Louis J. Maher, Jr. Department of Geology and Geophysics

University of Wisconsin-Madison Madison, Wisconsin 53706

INTRODUCTION

Europe Lake occupies a small basin near the tip of the Door Peninsula. The lake is separated from Lake Michigan by a sand bar and dune complex (Fig. 8 in road log). The main objective of coring Europe Lake was to date its isolation from Lake Michigan through growth of the bar and dunes. On February 22, 1992, AlIan Schneider, Marty Koopman, Coggin Heeringa, and the authors collected three cores from the southern part of the lake (Fig. 9 in road log) using a modified Livingstone piston corer. We collected the cores in approximately 2 m (6.5 ft) ofwater, and sediment recovery varied between 1.9 and 2.3 m. After extruding the cores on the ice, we sampled the uppermost few centimeters of flocculent sediment and sealed the remainder in plastic wrap and aluminum foil. Cores were unwrapped, measured, described, and sampled in a clean palynology laboratory and then re-wrapped for cold storage .

. SEDIMENTOLOGY

The sediment in all three cores ]s mainly gray marly gyttja. Beneath the gyttja is a thin (1 to 11 cm) peat or duff layer that contains wood, bark, and other plant macrofossils. In two of the cores, diamicton (5 cm) was recovered beneath the peat. The brown color and sandy texture of this diamicton resemble that of the till of the Liberty Grove Member of the Horicon Formation (Mickelson and others, 1984).

In the upper 130 to 140 cm ofthe gyttja, fossil mollusks (whole valves) occur in discrete partings, usually one or two shells thick, and not distributed throughout the sedimento Beneath this, mollusks are more abundant and are uniformIy distributed throughout the gyttja. In the lowest 25 cm of gyttja, shell fragments become increasingly abundant.

Correlation of the three cores can be accomplished by matching color changes in the gyttja. The uppermost few centimeters of highly flocculent gyttja is light olive gray; beneath that is 12 to 15 cm of dark-gray gyttja, which is under!ain by 48 to 53 cm of light-gray gyttja. This pattern of color alternations occurs throughout the gyttja. Near the base of the gyttja a thin bed (2 to 4 cm thick) of white mar! serves as a useful marker. Partings of fossil mollusks sometimes correlate between cores, but sometimes they do noto

CHRONOLOGY

A small sample (0.7 gm of carbon) of peat from irnmediately beneath the gyttja in core 1 (214-220 cm) was dated at 6,610 ± 150 yr B.P. (Beta-56310). The sample contained several small fragments of wood and bark but, nevertheless, required extended counting time. This provided a maximum age for initiation of gyttja deposition; for a number of reasons gyttja deposition may have begun more recently

53

tban 6,600 B.P. No otber dates have been obtained because of tbe potential for hard-water (reservo ir) effect. Because tbere are several well-dated poli en diagrams from lalces in east-central Wisconsin (West, 1961; Goodwin, 1976; Davis and otbers, 1986; Webb, 1987), we use tbe regional pollen stratigraphy and tbree pollen counts from tbe lower part of core 1 (190, 199, and 210 cm) to date tbe beginning of sedimentation in Europe Lalce.

PALYNOLOGY

There are tbree chronostratigraphic boundaries in pollen diagrarns from tbe region tbat have potential for dating tbe Europe Lalce gyttja and tbereby tbe isolation of tbe basin. The youngest is tbe historic ragweed (Ambrosia) rise tbat occurred at about A.D. 1850. Preliminary pollen counts place tbis boundary between 20 and 30 cm deep in Europe Lalce core 1.

American beech (Fagus grandifolia) migrated into tbe Europe Lalce area about 4,000 B.P. and eastern hemiock (Tsuga canadensis) reached tbe vicinity between 6,000 and 5,000 B.P. (Davis and otbers, 1986). The samples from Europe Lalce core 1 at levels 1.90, 199, and 210 cm all contain Fagus and Tsuga pollen. This suggests tbat lalce sedimentation began several tbousand years afier tbe date of tbe underIying peat.

FI'ax. Pinus QueI'cus Tsuga AlIIbI'osia Picea Betula Ullllus Fagus AI'telllisia OtheI'(9)

'J!I' BP , · • • , • - -Est. , • - • - • - - -, :' - • ::' • - , -• - • • - • -• - - • - ., · -• - - • - • - -• - - • - • - -• - - • - - • • 2000 , ¡¡¡, = , ¡¡, , , , ..,

• =- • • • , • - • - • • , -• - - • - · • • , -• - - • • , - • • -, - - • - • • , • 1 ~ - ~ - · • \ , ~ , = :::l , , - - • - : • • , -- - • - • , , -- - • - • , , • -· - • - - • , • · • ~ - - , ! • -3700 ::1 ::J 1 , , ii' :::- ~ - • , - • -- • - • -- • - • -- • - ':' -- - - -- - - • -- · - • = - - - • - • - -· • • - • • • - • • • ==- : - -· - -• - - - -• - · - -• - · - -, =-- • - -- , , • -- , , • - - -- , , , - - -- , • ~ = ~ - • • • - -- • • - - -- • • • - - -- • • - • -

EUI'ope Lake uso Seidel Lake H 20:1.

Figure 1. Three pollen samples from Europe Lake (open bars) inserted into the sequence of pollen samples from Seidel Lake (West, 1961). The Europe Lake samples from depths of 190, 199, and 210 cm match the Seidel Lake samples in the interval estimated to range from 2,000 to 3,700 B.P. The tick marks at the right mark every ten samples.

54

The nearest site from which a pollen diagram is available is 100 km to the southwest at the base of the Door Peninsula -- Seidel Lake in Kewaunee County (West, 1961). There are no carbon dates available from the original Seidel Lake cores. However, its sediment contains the ragweed rise of the last century; the basin lies on moraine of Greatlakean age and must postdate that ice advance. It is possible, using palynology, to correlate Seidel Lake with Kellners Lake, which lies an additional 35 km southwest in Manitowoc County (Goodwin, 1976). Thus the Kellners Lake 14C chronology can be carried to Seidel Lake and ultimately to Europe Lake.

Figure 1 shows a pollen diagram of Seidel Lake in which the Europe Lake samples (open bars) have been inserted by a mathematical "slotting" technique. The three samples from the base of the Europe Lake gyttja lie in the sequence estimated to range from 2,000 to 3,700 yr B.P. This suggests there was a hiatus of at least 3,000 years from the last accumulation of peat to the initial accumulation of gyttja.

ACKNOWLEDGEMENTS

Marty Koopman and Coggin Heeringa assisted with the coring. Marty Koopman, Andy Day, Steve Franklin, Robert Weseljak, Don Wendorf, and Tara Zwicky assisted in the laboratory with core description and sampling and with sample preparation.

REFERENCES ClTED

Davis, M. B., Woods, K. D., Webb, S. L., and Futyma, R. P., 1986, Dispersal versus climate; Expansion of Fagus and Tsuga into the upper Great lakes'region: Vegetation, v. 67, p. 93-103.

Goodwin, R. G., 1976, Vegetation response to the Two Rivers till advance based on a pollen diagram from Kellners Lake, Manitowoc Co., Wisconsin: unpublished M.S. thesis, University of Wisconsin"Madison. . .

Mickelson, D. M., Clayton, Lee, Baker, R. W., Mode, W. N., ami Schneider, A. F., 1984, Pleistocene stratigraphic units of Wisconsin: Wisconsin Geological and Natural History Survey Miscellaneous Paper 84-1, 97 p.

Webb, S. L., 1987, Beech range extension and vegetation history; Pollen stratigraphy of two Wisconsin lakes: Ecology, v. 68, p. 1993-2005.

West, R. G., 1961, Late- and postglacial vegetational history in Wisconsin, particularly changes associated with the Valders readvance: American ]ournal of Science, v. 259, p. 766-783.

55

MOLLUSCAN FAUNAL CHANGES IN EUROPE LAKE, WISCONSIN DURING THE PAST 6,600 YEARS

Barry B. MilIer Department of Geology Kent State University

Kent, Ohio 44242

INTRODUCTION

The author has had an ongoing interest in the timing and nature of the changes that have affeeted the molluscan faunas in the Great Lakes sinee deglaciation (MilIer and Kott, 1989). This preliminary study is based on molluscs reeovered from one of a series of three 2-m cores collected from Europe Lake and represents an extension of these investigations to an afea of the Lake Michigan basin that 1 have not previousl y examined.

STRATIGRAPHY

The stratigraphy in the three eores is quite similar (pers. comm., W. N. Mode). A radioearbon date of 6,610± 150 yr B.P. (Beta-56310) on peat at a depth of 214 cm from eore 3 suggests that the sediments in the cores started to aceumulate in the Europe Lake basin during the rise in the water level in the Lake Michigan basin from the low-water Lake Chippewa phase.· The sediments are predominantly a silty gyttja that have been subdivided into 13 units based on color changes. A summary description of the sediments recovered from core 2 are given in Table 1.

Unit DEPTH (em)

1 Oto 15 2 15 to 29 3 29 to 38 4 38 to 64 5 64 to 66 6 66 to 95 7 95 lo 100 8 100 to 121 9 121 to 131 10 131 lo 142 11 142 to 170

12 170 to 178 13 178 lo 192

Table 1. DESCRIPTION OF CORE 2 LITHOLOGY

Description

Silty Gyttja; dark grey (7.5YR 3/1) Silty Gyttja; light grey; (7.5YR 512) Silty Gyttja; dark brown grey (7.5YR 3/2) Silty Gyttja; Iight grey (IOYR 5/1) Gyttja; with > 2 mm plant fragments; dark grey (10YR 3/1) Silty Gyttja; grey (IOYR 4/1) mSm:mi LOST~~~ Silty Gyttja; grey (10YR 4/1) Silty Gyttja; dark grey brown (7.5YR 5/2) Silty Gyttja; dark grey (IOYR 3/1) Silty Gyttja; with dark-grey (IOYR 3/1) and Iight-grey (lOYR 4/1) bands Marly Gyttja; light grey (10YR 612) Gyttja and Mari; light-grey marls bands(10YR 5/2) and dark organic-rich bands (IOYR 4/1). Wood at 191-cm.

57

MATERIALS ANO METHOOS

The molluscs were recovered from a 192-cm core collected with a Livingstone sampler. The core was split, and starting at the core top al-cm subsample for ostracodes and a 4-cm subsample for molluscs was recovered at each lO-cm incremento The 4-cm samples were dried and washed through a series of 25 to 35 mesh sieves. A total of 1,776 individuals was counted. Ten species of molluscs were identified from these niaterials (rabie 2). The overwhelming majority of individuals belong to two species of prosobranch gastropods, Marstonia decepta and Valvata tricarinata. All the species are stillliving and have geographic ranges that include the study area.

Table 2. FAUNAL LIST OF MOLLUSCS FROM EUROPE LAKE CORE

TAXON ABUNOANCE

GASTROPOOA

Marstonia decepta 1070 252

Va/vata tricarinata 48

Amnico/a limosa 60 Helisoma anceps 48 Fossaria obrussa

9 Gyrau/us parvus 1

Planorbella campanu/atum 7 Physa sp.

1495 •

PELECYPOOA

Pisidium ferrugineum 46 32

Pisidium ventricosum 195 Pisidium spp.

8 Musculium partumeium

281

INTERPRETATION ANO DISCUSSION

Europe Lake is now apparently fed by ground-water discharge and precipitation. This inference is based on the observation that a 6-m elevation difference now exists between the Europe Lake and Lake Michigan water planes.

The molluscan fauna from between 170 and 185 cm includes a mixture of depauperate, broken and etched gastropod shells that occur in association with relatively abundant pisidiid c1ams. The condition of many of the shells suggests that they may have been exposed to subaerial weathering before burial.

58

Valvata tricarinata undergoes a significant increase at 160 cm and remains the most abundant species to 130 cm, where it is replaced in this dominance role by Marstonia decepta. Species diversity and abundance changes at a depth of between 120 cm and 130 cm divide the core into upper and lower molluscan faunal zones (Fig. 1). Below this depth, Marstonia decepta is less abundant than Valvata tricarinata, and these two species usually occur in association with Amnicola limosa and the pulmonate gastropods, Helisoma anceps and Fossaria obrussa. Above this interval, the two pulmonate species are almost totally absent, and Marstonia deceota overwhelms every other taxa in terrns of abundance. These changes in molluscan species diversity and abundan,e can be explained most parsimoniously in terms of water-level changes in the Europe Lake basin.

Shallow water below the 160-cm level is implied by the presence of Fossaria obrussa and Helisoma anceps, species that usually are found associated with abundant submerged vegetation in permanent water that is seldom morethan 50 to 100 cm deep (Burch and Jung, 1987). At this time the water depth at the core-2 site was shallow and supported an abundant aquatic macrophyte flora. The aquatic vegetation probably included Pomatogeton richardsoni and Myriophyllum exalbescens, two plants that are commonly found associated with Helisoma anceps, V. tricarinata and M. decepta (pip, 1978). The radiocarbon date from the base of core 3 of 6,600 yr B.P. suggests that the low-water level in Europe lake coincided with (1) the Nipissing transgression in Lake Michigan when the lake was still rising from the low-water Lake Chippewa phase (Larsen, 1987), and (2) a time when pollen records from the upper Great Lakes region suggest a warm, dry climate (Miller and Futyma, 1987).

The changes in species diversity and abundance, coupled with the almost total absence of pulmonate (air-breathing) snails from the upper molluscan faunál zone are interpreted as representing a time' when the water level in Europe Lake deepened. The irnmediate cause of this deepening was probably the rise of the Lake Michigan water plane to the 183-m Nipissing I level (Larsen, 1985). This event would either have inundated the Europe Lake basin or at least elevated the local water tableo

The replacement of Y. tricarinata by M. decepta as the dominant species might also be due to deepening of the water in Europe Lake. It is interesting to note here that water chemistry data compiled by Pip (1986) for aquatic gastropods from 412 sites in centralCanada suggest that y. tricarinata (::;;480mg/l) has a greater tolerance for chloride than M. decepta (::;; 8mg/l). Is it possible that the water chemistry in Europe Lake during the warm, dry climate inferred for the early Holocene from the pollen . record (Miller and Futyma, 1987) may have resulted in slight increases·in dissolved chloride that would have favored V. tricarinata? Higher water levels in Europe Lake would have resulted in dilution of the chloride and may have permitted M. decepta to compete more effectively with V. tricarinta.

The increase in water depth would reduce the area of shallow-water habitats near the coring site that supported the air-breathing pulmonates and probably led to their reduced abundance.

Although the water level in Lake Michigan subsequently lowered when the moderno drainage system through Port Huron became established (Larsen, 1987), the water level in Europe Lake remained relatively high, possibly in response to the onset of cooler, moister late Holocene climates indicated by many of the pollen records from the upper Great Lakes (Miller and FU!yma, 1987).

59

EUROPE LAKE CORE 2 MOLLUSCA

GASTROPODS PELECYPODS

I I

Marstonia decepta V. tricarinata A.limosa H. anceps F. obrussa Other Pisidium Pisidum Pisidium spp. Musculium ferrugineum ventricosum partumeium

l' 11 l' I I 1 I I I I I I I ¡¡ I I I l' I I I I F'l F'l F'l F'l Fl rnl I i ¡ 1I I ( ¡ m o 50 100% o 25% o 25% o 25% o 25% o 25% o 25% o 25% o 25% o

",;pTU utllT

" " " " " " '" " "

'" u, no , DO

" .. , '" u

'" 170 .

" '" " ""

<.05 I - ....

<.05 <.05 <.05 <.05

<.05 <.05 <.05 <.05

-, ... <.05

<.05 <.05 <.05 <.·05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05 <.05

<.05 <.05 <.05

<.05

m l' 1II l' I I F'l .Fl Fl Fl Fl rnl o 50 100% o 25% o 2-5% o 25% o 25% o 25% o 25% o 25% o

Figure 1. Relalive frequency of moIluses in core 2. Numbers in Ihe 'UNIT" column lo Ihe righl of the "DEPTH" scale refer lo Ihe lithologic units in Table 1. The two arroWS lo Ihe right of Ihe Musculium partumeium column indicale that less Iban 20 individuals were counled from Iha! leve!.

<:

'" o CIl en <: =ªo ON E-

'" ~ <: CIl :::J

8:.s . :::J

C:' ar '" <: ,~ o :::J N 15ai E§ ~'" CIl-;= .2

ACKNOWLEDGMENTS

Thanks are extended to Drs. Allan Schneider, William Mode, and Louis Maher, who collected Ihe cores and made Ihem available for study.

REFERENCES CITED

Burch, J. B., and Jung, Y., 1987, A review of Ihe classification, distribution and habitats of Ihe freshwater gastropods of Ihe North American Great Lakes: Walkerana, v. 2, p. 233-291.

Larsen, C. E., 1985, A stratigraphic study of beach features on Ihe soulhwestern shore of Lake Michigan; New evidence of Holocene lake level fluctuations: Illinois State Geological Survey Environmental Geology Notes 112, 31 p.

__ ,1987, Geological history of glacial Lake Algonquin and Ihe upper Great Lakes: U.S. Geological Survey Bulletin 1801, 36 p.

Miller, B. B., and Kott, R., 1989, Molluscan faunal changes in Ihe Lake Michigan basin during Ihe past 11,000 years: National Geographic Research, v. 5, p. 364-373.

Miller, N. G., and Futyma, R. P., 1987, Paleohydrological implications of Holocene peatland development in northern Michigan: Quaternary Research, v. 27, p. 297-311.

Pip, E., 1978, A survey of Ihe ecology and composition of submerged aquatic snail-plant cornmunities: Canadian Journal of Zoology, v. 56, p. 2263-2279.

__ , 1986, The ecology of freshwater gastropods in Ihe central Canadian region: Nautilus, v. 100, p. 56-66.

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61

•

I

I

I

I

I

I

THE OSTRACODE RECORD FROM EUROPE LAKE, WISCONSIN: THE PAST 6,600 YEARS

Alison J. Smitb and Beiwen Dai Department of Geology Kent State University

Kent, Ohio 44242

INTRODUCTION

The Europe Lake ostracode fauna provides a record of temporal changes in a small lake basin on tbe edge of Lake Michigan. Altbough probably affected during tbe past 6,600 years by tbe rise and fall of tbe Lake Michigan water level, Europe Lake has apparentiy remained isolated from Lake Michigan. There is no evidence of tbe ostracode fauna from Lake Michigan (Colman and otbers, 1990) in tbe Europe Lake core, even as reworked or transported material. The fauna presented here are characteristic of a small, dilute caIcium-magnesium-bicarbonate lake typical of tbose found tbroughout tbe Great Lakes region (Smitb, 199i).

METHODS

Three cores were taken from Europe Lake, one of which was radiocarbon dated. The tbree cores are· stratigraphically very similar (pers. cornm., W. N. Mode). The date of 6,610 ± 150 yr B.P. (Beta-56310) on peat from tbe base of core 3 is tbe source of tbe chronology in tbis analysis. Core 2 was described and sampled as discussed by Miller (tbis volume). Ostracode samples were taken from core 2 at lO-cm intervals, each witb a wet volume of 6 ce. Ostracodes were processed byfreezing tbe samples, mixing ihem witb hot (90 0 C) water buffered witb baking soda, and tben further disaggregated witb Calgon. The mixture of water and sample was tben washed tbrough a stack of tbree sieves of 20, 100, and 230 mesh. The size fractions were bagged, frozen, and freeze dried. The lOO-mesh size fraction contained most of tbe ostracode material. AH unbroken adult ostracode valves were counted in each sample.

RESULTS

Thirteen taxa of ostracodes are represented in tbe core, all of which are living in tbe region today (Table 1 and Fig. 1). The lower portion of tbe core, from 190 to 160 cm, is almost devoid of ostracodes. Many of tbose tbat are present are broken or abraded. The core section from 160 to 120 cm contains a large number of ostracode valves representing a permanent lacustrine fauna of Candona ohioensis, .c;. inopinata, .c;. distincta and Limnocytbere verrucosa. Species associated witb groundwater discharge, such as Candona elliptica and Darwinula stephensoni, and nektonic pond species, such as Cypridopsis vidua, are also present in abundance. The upper portion of tbe core, from 120 cm to tbe sediment-water interface, differs substantially from tbe lower part oftbe coreo Above 120 cm, tbe species associated witb permanent lake conditions decline, whereas tbose species tbat do well in more variable conditions, such as Cypridopsis vidua, increase.

63

o-~

.

Europe L., WI eore 2

é,9 ¿j.\oe""",

Analyst Beiwen Oai

• C)\.6 0",0 • AO~\<' . r-c\'C) ~e;

~ r-'<>o . ~e<;t~e ~\o\).o

~,~6 0(6<:f.

s(t< R 6 ~ ~(~,oe(' ~\~'Ó.cC) o cC)~~{< of:' C6('O~C)

O \,. ~i;;'<:> ~e co('oo<' o~o d-~e(e c6f:' 'I)~('o

'¡.,,('..y.6 ,i}.'" fJO('i- cfloOY

..J<;t~'" ~C) "'~ ~<;tll .~(('. :(Qe\ ~o'" ~\' '", ~ 0"- ",~~ 1?O .... ~ 1?~i'IfF "cFi<;t(' cF'l'Y~"',,'Y~'"

ole; oIG1 01C\cF'

20

40

60

,?eo o

'1:: 100 .... Q.

~12O

140

180

180

200

0203.2 640 306090120 02040 D 2040 O 6613.2198264020400 BB 1762640130 80 1800 2B04D8 number of valves/6 ce sample

Figure 1. Ostracode diagram foc Europe Lake, Wisconsin, COte 2.

Table 1. OSTRACODE SPECIES PRESENT IN EUROPE LAKE, CORE 2

Cyclocypris ampla Cyclocypris ovuni Cyclocypris sharpei Physocypria spp. Cypridopsis vidua Potamocypris smaragdina Darwinula stephensoni

Candona distincta Candona elliptica Candona inopinata Candona ohioensis Candona paraohioensis Limnocythere verrucosa

INTERPRETATION AND DISCUSSION

Tbe ostracode record indicates two major changes in the history of Europe Lake after 6,600 years B.P. Tbe first change occurs at 160 cm depth, and the second occurs at 120 cm depth. Tbe lower portion of the core, from 190 to 160 cm depth, is indicative of a very low water marsh, with subaerial exposure and possible erosion of fossil ostracodes from terraces aboye the present lake. Tbe molluscan • record from this part of the core supports this interpretation by the presence of pulmonate snails (Miller, this volume). Both the molluscs and the ostracodes are abraded and broken, indicating transport, reworking, and subaerial exposure. At 160 cm depth, species characteristic of a permanent lacustrine environment appear. Tbe abundanceof shells in the interval from 160 to 120 cm indicates either high productivity or a low sedimentation rateo Tbe water composition and concentration can be inferred from similar ostracode assemblages found in the region today, suggesting that the lake contained Ca-Mg-HC03 water, with concentrations that did not exceed 450 mg/L (Smith, in press). We interpret this permanent lacustrine condition as one associated with the rise in the Lake Michigan basin (the Nipissing transgression) following the low-water Lake Chippewa phase. Tbe presence of Candona elliptica and Darwinula stephensoni suggeststhat groundwater discharge was also important.

Above 120 cm depth, the number of ostracode valves declines for aH but a few taxa. Cypridopsis vidua and Limnocythere verrucosa are species tbat are associated with more variable lakes and ponds. Tbe moHusc fauna indicate a deepening at the core site for this interval, based on the increase in Marstonia decepta'and the disappearance of pulmonate gastropods (Miller, this volume). A water-level rise in the lake at the core site is not clearly indicated by the ostracode fauna, but the change to a more variable, less permanent condition is indicated. Tbere is no evidence that the lake water ever exceeded 450 mg/L in total concentration or has had a composition other than Ca-Mg-HC03. An oxygen isotope record from the ostracodes in the core would confirm a shallowing or deepening of the lake.

Although the water level in Lake Michigan is approximately 6 m below the core site today, Europe Lake continues to existo Graund-water discharge and atmospheric precipitation obviously supply the lake, and have probably done so since the decline of Lake Michigan water levels in response to the establishment of the Port Huran drainage system (Larsen, 1987).

ACKNOWLEDGMENTS

We thank AlIan Schneider, Williarn Mode, and Louis Maher, who collected the cores and made them available for study. We also thank Barry Miller for helpful discussions on the Great Lakes records and the moHuscan ecology.

65

REFERENCES CITED

Colman, S., Jones, G., Forester, R. and Foster, D., 1990, Holocene paleoclimatic evidence and sedimentation rates from a core in southwestern Lake Michigan: Journal of Paleolimnology, v. , p. 269-284. .

Larsen, C. E., 1987, Geological history of glacial Lake Algonquin and the upper Great Lakes: U.S. Geological Survey Bulletin 1801, 36 p.

Smith, A. J., 1991, Lacustrine ostracodes as paleohydrochemical indicators in Holocene lake records of the north-central United States: Ph.D. dissertation, Brown University, Providence, R.l.

__ ' in press, Lacustrine ostracodes as paleohydrochemical indicators in lakes of the north-central United States: Journal of Paleolimnology.

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66

NEWPORT VILLAGE: A WILDERNESS EXPERIMENT

Coggin Heeringa Newport State Park

ElIison Bay, Wisconsin 54210

In 1837, Sylvester Sybly made tbe first survey oftbe nortbern Door Peninsula. "Soil-- second rate" was his assessment for tbe area tbat is now Newport State Park.

Jt is unlikely tbat tbe pioneers ever saw his reporto They carne full of drearns, laboring under the misconception tbat land which could support huge trees must be more fertile tban grasslands. So settlers, predominantly German, Scandinavian, and Bohemian, carne into nortbern Door County to remove tbe valuable timber and at tbe sarne time to "improve tbe land for agriculture." Sadly, in tbis area tbeir best crops were rocks, and what was once wilderness has now reverted to near-wilderness.

A few farmers settled in tbe area in tbe 1870s, and in 1880 a Dane named Hans lohnson acquired 200 acres of timberland and witbin ayear announced to tbe world (or at least to readers of tbe Door County Advocate) tbat he planned to start a town. And he did, at a site now used as tbe picnic/beach area in Newport State Park.

Newport Bay is notoriously shallow, so during tbe first summer lohnson put in an enormous pier, a series ol' cribs supporting planks. By autumn tbe.pier was being used, altbough it wasstill incomplete. Two schooners were anchored at tbe pier when tbe fabled gales of November blew in from tbe east. According to tbe Door County Advocate of November 17, 1881, "Hans lohnson's new pier at Newport, near Rowleys Bay, was pretty badly demolished during tbe heavy gale from tbe east last Friday night. Two vessels, tbe scows "Forrest" and "Becker," were Iying alongside tbe structure at tbe time, when tbe storm drove tbem ashore and tbe pier was carried out with tbe vessels." The next issue reported tbat "immediately after tbe accident, Mr. lohnson, witb his characteristic energy and enterprise, went to work to rebuild tbe pier, and it will not be long before everything about Newport will be in a flourishing condition again. Whoop-Ia."

lohnson did more tban rebuild his dock. He stored tbe battered schooners in his barn, and when tbe owners offered tbem for sale at bargain prices lohnson purchased tbe R. H. Becker. By 1882, he owned tbat scow schooner, a pier, and a block of heavily timbered land. The people living in and around Newport referred to tbe entrepreneur as "Governor" Hans lohnson. A benevolent "governor," he built a general store-post office and cooperated witb neighbors to establish tbe Newport school at tbe site now occupied by Unele Tom's candy kitchen.

In tbe early years of tbe community, tbe forest commodity most in demand was cordwood. Following tbe Great Chicago Fire of 1871, brick became tbe building material of choice. The Milwaukee brickyards' insatiable appetite for hardwood provided a market for tbousands of cords of beech and maple from Newport each year. The Becker carried wood products to Milwaukee and Racine, returning witb goods for tbe store and building materials for tbe growing community. In addition to brickyard wood, lohnson sold shipments of fine maple, basswood, and birch to tbe Two Rivers Manufacturing Company and bolts of poplar to tbe new pulp mili in DePere.

As settlers pushed into America's West, a market grew for virgin pine lumber and otber forest products. During tbe 1887 season,,Johnson sold 11,000 cedar and hemlock railroad ties and 20,000 posts in Milwaukee, Racine, and Chicago.

67

Forest industries at Newport were not limited to wood production. In the 1880s, oil distilled from cedar was a major component of furniture polish, and from 1885 to 1887 this distillate was produced on the shores of Rowleys Bay. Johnson also shipped out more than a hundred cords of hemlock bark, the source of tannin used in leather production.

Johnson usually had at least 20 men working in his woods. They were paid one dollar a cord for wood -- cut, hauled, and banked on ·the Newport beach. When word arrived that a schooner was approaching, men and boys ran to the pier where 25 cents an hour was paid for loading wood. Considered a generous wage, this money helped many immigrants purchase land, which they c1eared for farming. Primarily woodcutters and farmers, the men of Newport would drop whatever they were doing, however, when fishing would bring in larger profits.

But even in times of prosperity, life was incredibly harsh. Tiny log cabins were chinked with moss to keep out the frigid lake winds. Scarlet fever and diphtheria were common and often fatal. In bad times, Johnson extended credit or just gave food lo the needy. Farm yields from the rocky lands often were insufficient for even home consumption. The community survived on hope and timber.

Times for Johnson were bad too. His wife Anna died in 1887. By most accounts, though not obvious at first, this loss marked a turn-around in the governor's fortunes. He began to drink heavily. In 1890, his pride and moneymaker, the R.H. Becker, capsized near Ahnapee with one man drowning. The cargo sank and the schooner, deemed irreparable, was sold at an enormous loss.

A lighthouse keeper on Pilot Island, Peter Knudson, kept his savings in Hans Johnson's safe at Newport. According to credible sources, when Johnson became short of money he began to dip ¡¡ito Knudson's savings, planning to pay it back in the future. By the time Peter Knudson returned to shore lo check on hiscash, Johnson had drunk up Knudson's entire savings. Whatever might have transpired between the Iwo men, by 1892 Peter Knudson had become Johnson's partner and was appointed Postmaster at Newport. Captain Knudson continued his career with the lighthouseservice and also sailing the ship "The South Side" between Newport and other Lake Michigan ports.

During the 1890s, the village boasted a population of 300, including a pump manufacturer, a wagon maker, a shoemaker, and a blacksmith. But Johnson lost another boat, the "Lettie May," in the Sturgeon Bay ship canal and continued to lose money on every wood shipment. By 1895, he had sold the remainder of his business and much of his property to Peter Knudson for $2;000 and left the area, but he returned several years later to work for his former partner.

Knudson employed a large force of woodchoppers and teamsters who worked under foreman Hans Johnson. When Knudson was gone, working for the lighthouse service or sailing, Johnson also ran the store and pier. But by the turn of the century, the village of Newport was slowly transforming into an agricultural community. Knudson continued to carry logs from Newport to Milwaukee, but in addition to wood he carried cargos of grain and potatoes.

Hans Johnson was also elected to serve as Liberty Grown Town Treasurer. But by 1905 the whispered reports of a scandal became publico Buried in the Advocate, a small item read "It is now definitely known that the deficit in the account ofTown Treasurer Hans Johnson is approximately $2,750, an expert having gone over the books during the past weeks ... The defalcation did not surprise any one who had kept in touch with the trend of affairs in the treasurer' s office for the past year or so."

The rumors Were true. Johnson had drunk up the town funds, bringing the area bondsmen to financial ruin and rendering the town helpless to pay even its school teachers. Accepting the charity of friends, Johnson returned to the farm he once owned and attempted to retrieve his losses. Several months

68

later the Advocate reported that he was dying of tuberculosis. Finally, ex-Assemblyman, ex-Town Treasurer, ex-"Governor of Newport," Hans Johnson accepted ajob in the forests of the Upper Peninsula and was never heard from again.

Lake shipping was slacking off, so in 1908 Peter Knudson established a large saw, shingle, and lath mili on the shores of Newport Bay. At first lumber was shipped elsewhere, but the area was growing and twenty employees were kept busy doing custom milling for local farmers.

At the same time, the northern end of Door County was establishing a reputation for natural beauty. The tourist industry was born. The only problem was lack of transportation. Autos were few and roads abominable. Tourists could not reach northern Door, nor could area farmers find eco no mi cal markets . for their produce. So when, in 1913, a group of investors proposed a railroad from Sturgeon Bay to Newport, a stock issue of $75,000 was eagerly snatched up by area subscribers. This golden opportunity was not lost on Knudson. His son Herbert went to Sturgeon Bay to work out details of the plan with railroad surveyors while Knudson entered into a contract with the development firm, E.E. Gane Company. This company helped Knudson plat an elaborate crescent-shaped city stretching from Europe Bay south to Rowleys Bay. The property was subdivided into 751 lots, most of which were intended for summer homes.

Newport was surveyed and a crew of workers began clearing and leveling the twenty planned streets. Unfortunately for Knudson, the railroad plan fen through. Except for a sman commission, investors got their money back, and most patriotic citizens reinvested their money in war bonds, for World War 1 loomed even on the Door County horizon. Not wanting to pay taxes on platted land, Knudson petitioned to vacate the plan. Courthouse records state, "None of the streets or avénues or public beaches or public places indicated on said plat have been used or occupied or accepted by the public in any way whatsoever. None of the avenues or streets have been laid out or opened or worked or made fit for travel, or improved in any way whatsoever. NOTHING has been accepted by the public."

There would be no railroad, no town, and probably no more shipping. In 1919, 37 years after its beginning, the village met its end. Newport VilIage had become a farm. In the Sturgeon Bay Advocate the headline read "Peter Knudson Holdings in Liberty Grove Sold to Ferdinand Hotz." Hotz was a Chicago diamond merchant who summered in Fish Creek; he purchased 1,015 acres, including the Newport buildings. According to the newspaper account, Hotz had originany intended to subdivide the shoreline lots and sen them as resort property'. But instead the Newport area became a Hotz family retreat. Most of the land remained in the Hotz family until 1964, when the land and rotting ghost town were purchased by the Wisconsin Department of Natural Resources for use as a state park. What was once wilderness is now wilderness again.

Editor's Note: Mrs. Heeringa is the naturalist at Newport State Park and also writes a column for the Door County Advocate. This article is excerpted from a chapter on the history of Newport that will appear in a forthcoming book.

69

1

BEACH RIDGES AND LAKE-LEVEL IDSTORY AT TWO RIVERS, WISCONSIN

Eric Dott Delta Environmental Consultants, Inc.

St. Paul, Minnesota 55112

INTRODUCTION

Point Beach State Forest and nearby Woodland Dunes Nature Center encompass two beach-ridge complexes located north and south, respectively, of the mouth of the East and West Twin Rivers at the city ofTwo Rivers on the western shore ofLake Michigan (Fig. 1). The beach-ridge complexes preserve a record of Holocene lake-level fluctuations and shoreline progradation. The oldest ridges may be as old as 4,000 to 5,000 yr B.P. The ridges east of County Highway O along the access road to the park office building have been dated from 3,000 yr B.P. to modern (Dott, 1990).

DESCRIPTION

The northern or Point Beach ridge complex is composed of 0.5- to 8-m high, closely spaced subparallel ridges that trend north-south. The complex is bordered on the west by the broad, flat Molash swamp. West ofthe swamp is a sharp wave-cut till scarp with associated dune sands trending north from the Two Rivers Moraine at Two Rivers. This scarp forms the western limit for the Holocene lake deposits (Fig. 1). The ridges in the Point Beach complex are separated by narrow low swales, which in many locations are filled with standing water, wetland vegetation, and accumulated peat deposits.

The Woodland Dunes ridge complex covers a smaller area. Ridges at this site are interspaced with wide swampy swales arranged in a fan-shaped pattern. These ridges and s'wales diverge to the north, where they are truncated by the Twin Rivers lowland. This ridge complex is also backed on the west by a poorly developed wave-cut terrace (Fig. 1).

DETERMINATION OF PAST LAKE LEVELS

Beach ridges represent positions of past shorelines. The ridges are dune capped and have a core of back-beach laminated sand over foreshóre coarse-grained laminated and cross-laminated sediments. The foreshore deposits extend beneath the adjacent lakeward swale. Foreshore sediments are underlain by rippled cross-laminated or parallel laminated fine- to medium-grained sands of the upper shoreface facies.

Former lake-level elevations, represented by foreshore deposits beneath the lakeward sides of beach ridges, have been dated with radiocarbon dates obtained from peat deposits in swales between the beach ridges (Dott, 1990; Thompson and others, 1988). Auger drilling, closely spaced vibracoring, and ground-penetrating radar profiling along two east-west transects, one at Point Beach and the other at Woodland Dunes, provided the subsurface data and age-dating material with which to reconstruct the lake-level history for this area (Fig. 2). Tables 1 and 2 surnmarize the radiocarbon dates from the two sites.

71

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72

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TABLE 1. RADIOCARBON DATES FOR POINT BEACH TRANSECT (Transect A-A')

Material S.mple # Date' Reference # t doted (thicknessttl glevutlnn (m a.s.l.)

Tranucr A-A' (sites Usted (rom eosl lo weSl );

Mn·5·11·88·3 (Entrance swalc) modero ISOS·1948 wood and basal pea! . 177.2 m (6 cm)

Mn-5·1I·88-1 (Osta8c swalc) 620 +/- 80 Beta·29618 wood Crom peal 176.6

Mn·I6-IQ.88·IB (ThundcrslOml swalc)" 1,180 +/- 70 ISOS-1937 wood in peal 178.1

Mn-\S·IQ.88-3B (wcs.\ Molash swamp) 1,630 +/- 70 ISOS-2055 upper peal 176.9

Mn-31-8-88·1 (Snakcswalc) 1,390 +/- 130 IS05·1935 basal peal 177.5

Mn·26-8-88·3 (CIam .wale) 1,540 +/- 70 ISOS·1957 (9 cm)

basal peal 177.7 (6 cm)

Mn-16-1Q.88-1 (Thunde:suxm swalc)" . 1,600 +/- 70 1505·1934 basal peal 178.0

Mn·5·11·88·5 (Hwy '0' .wale) (9 cm)

3,150 +/- 110 Beta·29220 basal peal 175.6 (13 cm)

Mn·15·1Q.88-3 (wCSI Molash swamp) 4.750 +/. 90 ISOS·1958 buricd peal layer 176.2 (9 cm)

Mn-87.()7-12-3 (wCS! MoIash swamp) 5,740 +/. 120 Beta·2SS66 basal pea¡ 174.5 (6 cm)

t.!n·I23 (WI Molash swamp) 5,970 +/- 80 ISOS'1936 drifiwood Crom sand 162.0 abovc red clay diall1ic1

, Radiocaroon dates are repor1ed as 'coovcn~onal'date in Radlocarbon y .... beCore !he .. fcrcnce ycar A.D. 1950. ISOS dalCS are co",:clCd . for uOlOplc Cracllonacton, bUI are nol eorreclcd for!he error in 14c half·me. ,. 5ame sile. t lIIinoi. Stato Geolo~ícul Survey,

Radiocarbon Iaboratory and Beta Anal~c, Inc., COfllI Oables, Florida 33124. tt Thicknesó oC peal horizon dOled.

TABLE 2. RADIOCARBON DATES FOR WOODLAND DUNES TRANSECT (Transect B-B')

Sample #

Mn·¡¡·9-88·5 (Wooduckswalc)

Mn-1Q.9·884B (Musl:nI1 swaIc)

Mn-IQ.9·884 (Musl:nI1 swaIc)

Material Dute' Reference # t dOled (thicknesstt) ~:Iev.tinn (m a.s.I.)

Transeet B-8' (sites listed (rom taSI (O west);

4,380 +/- 90 ISOS·1933 basal peal 180.3 m

5,640+/- 90 ISOS-2056 basal peal 179.6 (29 cm)

6,100 +/- 90 ISOS-I947 detrital wood from 179.3 sand below peal

, Radiocarbon dates are reponed as "convcnoonal" date in Radlocarbon years before!he .. Cuenco year A.D. 1950. ISOS dates are correclCd for isolopic Cractionacton. bUI are no! corrccted CO!!he error In 14C half·life. ,. Same sit •. t Illlnols Stato Oeologicul Survey, Radlocarbon Iaboratory and Beta Analytic, Inc., COfllI Oables, Florida 33124. tt Thíckncss of peal horiwn dated. .

73

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Figure 2. Hypo!hesized late Holocene lake-Ievel trends at Two Rivers based on stratigraphy, morphology, and radiocarbon dates atPoin! Beach State Forest and Woodland Dunes NalUre Center .. Stippled pattem denotes lake levels defined by elevation ranges of abandoned shore fealUres and associated trangressive sediments. Vertical bars constrain salid curve based on range of stratigraphic indicators and radiocarbon dates; curve is dashed where inferred. Remaining dates are plotted as points (boxes) on curve. The post-Algoma curve defines only !he high lake levels at Two Rivers; evidence from southem Lake Michigan (Larsen, 1985, 1987, 1990) indicates that lake level a1so fell below the modem mean elevation during lhis periodo

BEACH-RIDGE FORMATION

.Formation of a new beach ridge may occur in response to a chaoge in lake level, a chaoge in sediment influx to the shoreline, or a combination of these factors. Figure 3 illustrates the features of the beach ridges aod swales aod their relationship to a modern shore environment.

Sediment accumulation aod probably beach-ridge formation are processes that occur in localized settings along a shoreline reach, where coastline structure, longshore drift, aod· a sediment source combine to form a progradational beach-ridge complex such as at Two Rivers (Reineck aod Singh, 1986; Curray aod others, 1967). The ridges aod swales on the entraoce road to the park contact station are typical of the Point Beach ridge complexo Vegetation on back-beach dunes helps to stabilize aod build up the dunes which typically cap beach ridges (Fraser aod Hester, 1977; Davies, 1957; Shepard, 1960; Bird, 1960; McKenzie, 1958). The initial ridge may be a low wave berm or exposed miar-shore bar which then is built up by vegetation entrapment ofwind-blown beach saod. With favorable low lake level aod net accumulation of sediment along the shore reach, the ridge may be preserved by a vegetated dune cap (Dott, 1990; Fraser aod Hester, 1977; Curray aod others, 1967; Psuty, 1965).

74

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Figure 3. Schemalic diagram of ridges and swales showing localions of basal peal deposita used lo date !he formation of adjacent lakeward beaches. Organic delrital malerial is assumed lo have I1ccumulaled shortly after !he formalion of a new ridge.

RIDGE ALIGNMENT AND STRUCTURE

Chariges in a1ignment of lhe beach ridgeS occur at bolh of lhe ridge complexes at Two Rivers, resulting in eíght distinct groups of subparallel ridges (Fig. 1). Such realignments result in lhe truncation of part of lhe ridge complex produced by charige in sediment suppIy, water level, or wave energy (Reineck arid Singh, 1986; Curray arid olhers, 1967).

Stratigraphic cross sections (Figs. 4 arid 5) arid ground-penetrating radar profiles indicate lhat lhe ridge complexes are composed of a series of discontinuous stacked lenses of beach deposits distributed laterally arid dipping towards lhe lake. This pattern reflects lhe progradational growth of lhe ridge complexes. Realignments of lhe shoreline are seen in lhe subsurface ground-penetrating radar profiles as lakeward dipping erosional contacts lhat originate at lhe Iocations of ridge realignments. There are at least seven such realignments of lhe ridge pattern arid eight groups of parallel ridges, as shown in Figure 1.

LAKE-LEVEL HISTORY AT.TWO RIVERS

The lake-leveI history interpreted from cores a10ng lhe transects A-A' (Fig. 4) arid B-B' (Fig. 5) is based on lhe rarige of elevations obtained by measuring lhe eIevation of lhe top arid base of foreshore deposits benealh beach ridges. The timing of lhe lake-level chariges was determined by dating basal peat deposits from swales between beach ridges arid detrital wood deposited in transgressive sarids. The elevations of lhe tops of foreshore deposits formed in lhe last 3,000 years rarige between 0.2 arid 2.0 m above lhe modern meari lake level. The elevation of lhe base of lhe foreshore deposits for lhe last 3,000 years rariged from -0.3 to + 1.7 m relative to modern mean lake elevation (Fig. 2). Using lhe base of lhe foreshore as lhe best lake-Ievel indicator, lake level at Two Rivers apparently has reached as high as

75

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1.7 m aboye modern mean lake level for sufficient lengths of time to deposit foreshore deposits during the past 3,000 years.

The overall pattern of the foreshore deposits in the outer beach ridges at Point Beach shows no extreme elevation changes. Resolution of lake-Ievel changes of less than ± 0.5 m would be difficult to achieve using the aboye method of mapping the foreshore. This is due to uncertainties caused by the variability in the overall thickness of the foreshore deposits, which ranged from 0.25 to 1.0 m thick; by possible errors in eore measurement and deseription of ambiguous facies contaets; by resolution of surveyed elevations fOf features with variable· topography, such as beach-ridge crests (survey measurements were calculated to an accuracy of ± 0.01 m); and by difficulties in determining the attitude and position of the foreshore in the subsurface between widely spaced core localities.

The elevations plotted in Figure 2 for the past 3,000 years only apply to lake level highs during this periodo It is possible, of course, that unrecorded low-water levels occurred between the times of high level represented by the mapped foreshore deposits.

The Holocene lake-level history of the Two Rivers shore can be interpreted in two ways based upon the stratigraphic evidence and in the larger context of Lake Michigan basin lake-Ievel chronology. For the Lake Michigan basin, three major transgressions (Nipissing I, Nipissing II, and AIgoma) have been identified between 6,500 and 3,000 yr B.P. (Hansel and Mickelson, 1988; Larsen, 1985). For the Two Rivers site, the Holocene lake-Ievel fluctuation curve (Fig. 2) indieates that at least three major transgressions occurred, at about 6,500 yr, 4,800 yr, and 4,300 yr B.P. A fourth lake-Ievel rise occurred around 3,200 yr B.P.

As stated, the Holocene lake-Ievel history of the Two Rivers shore can be interpreted in two ways from the stratigraphic evidence. One interpretation assigns an early transgression to a level aboye 180 m eleva!Íonbefore 6,100 yr B.P., which coincides with the Nipissing I event describedby Hansel and Mickelson (1988). The second transgression of 179 m high, around 4,800 yr E.P., equates with the Nipissing II transgression (Hansel and Mickelson, 1988). Progradation combined with alto 2 m drop was followed by the AIgoma transgression, whieh raised lake level back up to 181 m at 4,500 to 4,300 yr B.P. (Fig. 2). The shore then prograded eastward as the lake gradually dropped; smaller 1 to 1.7 m lake-Ievel fluctuations (above modern mean) occurred throughout the period from 3,000 B.P. to present.

A second interpretation attaches younger ages to the Nipissing I and II transgressions of 4,800 to 4,200 B.P. (Fig. 2). In this scheme, the AIgoma transgression would be assigned a date sometime younger than 3,400 yr B.P. The most recent events, from 3,000 B.P. to present, are the same for either interpretation. .

The lake-Ievel fluctuation curve of Figure 2 applies only to the Two Rivers area; comparisons with other sites should take into consideration differenees in isostatic uplift within the Lake Michigan basin. Maximum lake levels at the Illinois Beach area, aceording to Larsen (1987), rose to 1.5 m aboye modern mean lake leve!" over the past 3,000 years. Larsen (1985, 1987) also found evidence of low lake levels that suggest that the lake dropped as low as -1.5 m during this same time periodo

Thompson (1990) has studied the stratigraphy ofbeach ridges in northwest Indiana at the southern Lake Michigan shore using vibracoring methods similar to those used for this study. He reports that the elevation changes of the base of foreshore deposits in the Indiana Dunes National Lakeshore area reach up to 2.0 m aboye modern-day mean lake level (176.3 m) for the last 3,000 years.

The locations of Larsen's and Thompson's study areas are south of the zero isobase line of isostatic uplift of the controlling outlet at Port Huron (Larsen, 1985, 1987; Thompson, 1987). Because

78

of isostatic uplift of the northern lake basin relative to the southern lake basin, the southern Lake Michigan shore would have experienced a slight transgression of the lake during the last 3,000 years. This rise in lake level at the southern Lake Michigan shore due to isostasy would be superimposed on climatically induced lake-level changes. However, there is no significant difference between the high lake levels at Two Rivers (1.7 m) and the sites to the south (1.5 m, Larsen, 1987; 2.0 m, Thompson, 1990). The isostatic change appears to be too small to resolve for the last 3,000 years.

REFERENCES CITED

Bird, E. C. F., 1960, Formation ofsand beach ridges: AustralianJournal ofScience, v. 23, p. 349-350. Curray, J. R., Hemmel, F. J., and Crampton, P. J., 1967, Holocene history of a strand plain lagoonal

coast, Nyarit, Mexico, in Castanares, A. A., and Phelger, F. B., eds., Coastal lagoons; A symposium: Universidad Nacional Autonoma, Mexico, p. 68-100.

Davies, J. L., 1957, The importance of cut and fill in the development of sanct beach ridges: Australian Journal of Science, v. 19, p. 107-109.

Dott, E. R., 1990, Stratigraphy and lake level history of a beach ridge complex at Two Rivers, Wisconsin, on the northwest shore of Lake Michigan: unpublished M.S. thesis, University of Wisconsin- Madison, 222 p.

Fraser, G. S., and Hester, N. C., 1977, Sediments and sedimentary structures ofa beach-ridge complex, southwestern shore ofLake Michigan: Journal of Sedimentary Petrology, v. 47, p. 1187-1200.

Hansel, A. K., and Mickelson, D. M., 1988, A reevaluation ofthe timing and causes ofhigh lake phases in the Lake Michigan basin: Quaternary Research, v. 29, p. 113-128.

Larsen, C. E., 1985, A stratigraphic study of beach features on the southwestern shore of Lake Michigan; New evidence of Holocene lake level fluctuation: Illinois State Geological Survey Environmental Geology Notes 112, 31 p.

__ , 1987, Long term trends in Lake Michigan levels, a view from the geologic record, in Wilcox, D. A., Hiebert, R. D., and Wood, 1. D., eds:, Proceedings of the First Indiana Dunes Research Conference; Symposium on shoreline processes:U. S. Department of the Interior, National Park Service, Science Publications Office, Atlanta, Georgia, 52 p.

__ , 1990, Isostatic uplift rates and the reconstruction of lake level changes in the Lake Michigan­Huron basins: U.S. Geological Survey Open File Report 90-272, p. 7.

McKenzie, P., 1958, The development of sand beach ridges: Autralian Journal of Science, v. 21, p. 213-214.

Psuty, N. P., 1965, Beach-ridge development in Tabasco, Mexico: Annals of Association of American Geographers, v. 55, p. 112-124.

Reineck, G. E., and Singh, I. B., 1986, Depositional sedimentary environments: Springer-Verlag, Berlin, 549 p.

Shep¡u:d, F. P., 1960, Gulf coast barriers, in Shepard, F. P., Ph1eger, F. B., and vanAndel, T. H., eds., Recent sediments, Northwest Gulf of Mexico: American Association of Petroleum Geologists, Tulsa, Oklahoma, p. 197-220.

Thompson, T. A., 1987,Sedimentology, internal architecture and depositional history of the Indiana Dunes National Lakeshore and State Park: unpublished Ph.D. thesis, Indiana University, Bloomington, Indiana, 308 p.

__ , T. A., 1990, Preliminary assessment of late Holocene lake-level variation in Lake Michigan: U.S. Geological Survey Open File Report 90-272, p. 6.

Thompson, T. A., Fraser, G. S., and Olyphant, G., 1988, Establishing the altitude and age of past lake levels in the Great Lakes: Geological Society of America Abstracts with Programs, v. 20, p. 392.

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•

Hydrogeology and Water Quality in the Fractured Dolomite Aquifer, Door County, Wisconsin

I ntrod uction

Kenneth Bradbury and

Maureen Muldoon

Wisconsin Geological and Natural History Survey

The majority of residents in Door County rely on the fractured Si/urian dolomite aquifer as their sole source of groundwater. The area has a history pf elevated nitrate, chloride, bacteria, and occasionally, lead levels in groundwater samples collected from private and public wells. Such contamination is believed to be a direct result of agricultural and other land-use practices in areas where thin soils overlie the fractured dolomite. Soil cover is thin over much of Door County, providing little pollution attenuation potential. Numerous fractures in the dolomite control the hydraulic conductivity of the bedrock aquifer. Each fracture, if open, can provide a direct route for infiltrating water to recharge the groundwater flow system. (see figures 1 & 2)

Background In May 1984, the Upper Door Watershed was selected as a Priority

Watershed under the Wisconsin Nonpoint Source Water Pollution Abatement Programo The Upper Docir Watershed Project is unique in Wisconsin's Nonpoint Source Pollution Program beca use it is the first wátershed project selected primarily for the purpose of protecting and improving groundwater quality.

The agencies working on the Upper Door Priority Watershed Plan desired a measure of the effectiveness of nonpoint pollution containment measures in reducing groundwater contamination. Despite many previous studies and sampling programs, the existing data were not sufficient to allow any definitive statements about the existing groundwater quality in Door County. Therefore, the Wisconsin Geological and Natural History Survey (WGNHS); in cooperation with the Wisconsin Department of Natural Resources (DNR), the Door County Soil and Water Conservation Department, and UW-Green Bay; initiated a study to 1) determine background concentrations of water quality parameters, 2) quantify spatial and temporal variations in groundwater quality in a portion of northern Door County, and 3) characterize the groundwater flow system in the county.

81

Results Water Ouality

1. Long-term monitoring of 14 existing domestic wells indicates that water quality is quite variable through time and that single groundwater samples may not provide an accurate picture of groundwater quality for a given well (see figure 3). These large variations in groundwater quality may be due to rapid groundwater movement through fractures. Water quality parameters measured include nitrate, chloride, turbidity, conductivity, sulfate, potassium, and bacteria.

2. Although water quality is quite variable, some general trends can be noted (se e figure 3). The four domestic wells plotted in figure 3 are located within 5 miles of the research site. The fact that such widely spaced wells show similar trends in groundwater quality parameters suggests that the contamination sources are diffuse, nonpoint sources that cover a broad area of the landscape.

3. Sixty-five domestic wells and five springs were sampled on a regular basis between February 1986 and August 1987; sampling has continued at 14 wells through June 1990. These samples indicate that 60% of the wells had bacteria present more than 25% of the time (25% was assumed to be due to sampling errors resulting in false positives) and 16% of the wells had average nitrate concentrations in excess of the 10 mg/l drinking water standard (NO; as N).

Flow system 1. There are two flow systems in the fractured dolomite aquifer. At the study site,

there is a shallow water table, 20 to 40 ft below the land surface and a deep potentiometric surface 'at approximately 150 ft below the land surface. Previous "water-table" maps of the area were based on measurements in deeply cased domestic wells and they incorrectly delineated a deeper potentiometric surface as the water table. A shallow water table means that contaminants applied at the land surface can enter the groundwater flow system more easily than previously assumed.

2. A very conductive fracture zone, located about 170 ft below the land surface, leads to very high groundwater velocities. A numerical model of the study area indicated that groundwater can move at rates up to 1.5 mile/yr (22 ft/day). A tracer test, conducted at the study site, indicated that groundwater in the deep flow system can travel as rapidly as 75 ft/day (5 mile/yr). While these values are not in perfect agreement, both suggest that groundwater velocities are quite high.

3. Water levels fluctuate over a wide range at the research site and both systems respond rapidly to snowmelt events, indicating that they are directly connected to the land surface. (see figure 4)

4. Pump tests indicate that the hydraulic conductivity of the deep zone is much greater than that of the shallow zone.

5. Seasonal recharge events can cause temporary reversals in the regional groundwater gradient. Since groundwater flow directions are controlled by the hydraulic gradient, such reversals make it difficult to accurately predict groundwater flow directions. (see figures 5 & 6).

82

Figure 1 Numerous vertical and horizontal fractures in the dolomite apparently control the hydraulic conductivity of the aquifer. Photo shows near,vertical fracture expression in an alfalfa field across from the Sevastopol research site. The near'vertical fractures are filled with fine'grained soil, which holds more moisture than surrounding rocks. The photo shows the frequency and regularity of fracture spacings. Horizontal fractures are also relatively common at the site. Geophysical logs, including television logs, indicate several high-conductivity horizontal fractures at depth. (see figure 2)

83

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Figure 2. Geophysical 109s for well MW1 at the Sevastopol site. Dashed horizontal lines indicate horizontal fracture zones.

84

EXPLANATION OF GROUNDWATER QUALlTY PARAMETERS Nitrate is a form of nitrogen that is commonly derived from fertilizers and animal

wastes. The recommended public drinking water standard is 10 mg/l of N03" as N. A mg/l is 1 part per million. In natural groundwater nitra te levels are low, usually under 2 or 3 mg/l. Nitrate is easily dissolved in water and it is not attracted to soil particles; as a result it is a good indicator of groundwater movement. High nitrate levels are sometimes an early warning that other contaminants may be in the water.

Figure 3 Plots of nitrate-N values versus time for four domestic wells in northern Door County. Dashed vertical lines mark the beginning of calendar years. AII the wells show a significant increase in nitrate-N concentrations occurred in all four wells in December 1987, followed by a gradual decrease in concentrations during the spring of 1988. Other simultaneous changes in concentration include an increase in October 1986, December 1988, and April 1990.

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1986 1987 1988 1989 1990

85

Figure 4 Graph showing the water-Ievel fluctuations for the shallow and deep systems. Significant temporal water-Ievel fluctuations occur at the Sevastopol test site, and water-Ievel fluctuations in the deep zone are greater than in the shallow zone. Water levels in piezometer MW2A, finished in the deep system, fluctuated by up to 95 ft in response to seasonal recharge. The most significant water-Ievel rises occurred just after snowmelt in March, 1988. Well MW3, finished in the shallow zone, fluctuated only about 45 ft during the observation periodo

The rapid response of the shallow and deep piezometers to spring snowmelt suggests that both systems are directly connected to the land surface. The two systems respond differently during dry periods. The water level in MW3 (shallow system) drops sharply and then stabilizes at approximately 740 ft above sea level (depth 55 ft); the water level in MW2A (deep system) continues to drop steadily throughout the summer. The large and rapid water-Ievel fluctuations in the deep system probably are caused by the presence of pror'ninent conductive fracture zones not present in the shallow system.

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86

I I .

POTENTIOMETRIC SURFACE

SEPTEMBER 1989 MARCH 1990

Figure 5. Configuration of the potentiometric surface in the 15 mi2 subarea of central Door County in September 1989 and March 1990. Contour interval is 20 ft.

SHALLOW WATER TABLE

SEPTEMBER 1989 MARCH 1990

Figure 6. Configuration of the water table in the 15 mi2 subarea of central Door County in September 1989 and March 1990.

87

•

THE TWO CREEKS BURIED FOREST

Robert F. Black

Reprinted from Wisconsin Geological and Natural History Survey Information Circular 13, 1970

INTRODUCTlON

Two Creeks is a small town 10 miles norlh of Two Rivers, near the west shore of Lake Miehigan in east­central Wiseonsin (Fig. O. James W. Goldthwait in 1905, while studying abandoned shorelines of eastern Wis­eonsin, observed portions of a buried forest soil with trees and logs exposed along the lakesho;e southeast of the town. His report (Goldthwait, 1907) brought to the seientifie eommunity a brief deseription of what has sinee beeome an internationally famous stratigraphie horizon, the Two Creeks Buried Forest. The time interval represented in part by the buried forest has been ealled Twoereekan (Frye and Willman, 1960). It is a substage of the Wiseonsinan Stage (Frye, Willman, Rubin, and Blaek, 1968), and as suggested by them, represents the radioearbon interval about 11,000 to 12,500 years B.P.

This find of buried organie malter was not the fírst in Wiseonsin. Notiees of buried wood in southern Wis­eonsin go baek to the 1840's, and Whittlesey (Owen, 1852, p. 436) mentioned !he presenee of buried wood in a dug wel! at Appleton, 45 miles west of Two Creeks. Lawson (1902) and Thwaites (1943, p. 136) mention other loealities. Beeause of its exposure along the lakeshore, the Two Creeks site was visited frequently, even though it was not studied in detail for deeades after its diseovery.

Wilson (1932 afid 1936) fírst started detailed studies of the fossil assemblages of trees, mosses, mollusks, inseets and pollen. A stratigraphie seetion appeared in Alden (1932, p. 43). Thwaites and Bertrand (1957, pp. 855-864) summarized the available information on the geology of the loeality whieh was one of the stops for INQUA, Exeursion C (Blaek, Hole, Maher, and Freeman, 1965) and other fíeld trips (e.g., Thwaites, 1953; and Prouty, 1960). Other workers eheeked partieularly on mosses (Culberson, 1955), pollen (West, 1960, and radioearbon age (Broeeker and Farrand, 1963). The site also has be en used in a Committee for Institutional Cooperation (CIC) Instruetional Improvement Program (Blaek, Clark, and Hendrix, 1968). Several other loeali­ties with equivalent-age butied forest horizons are now known in Wiseonsin (Fig. 19), but the type loeálity is slill the best exposed and best known.

Several isolated oeeurrenees of !he buried forest are found along Ihe lakeshore in the vieinity of Two Creeks. That whieh is most aeeessible today is direetly south of the Kewaunee-Manitowoe County line at a smal! temporary shelter (Fig. n. The property is owned by The Nature Conservaney and is being held as part of the future "Ice Age National Seientifie Reserve" of Wiseonsin (National Park Serviee-Wiseonsin Depart­ment of Natural Resourees, 1968).

OUTLlNE OF STRATlGRAPHY

In the bank of Lake Miehigan, whieh rises today about 30 feel above water level (Fig. 5), is a detailed sequenee of deposits (Fig. 6) whieh .depiet vast ehanges in elimate and in geologie events from a time perhaps 14,000 radioearbon years ago to the presento Stratigraphieally, the bank shows at water level a eompaet, red to gray elayey till and massive lake deposits of similar appearanee (5 YR 6/3 Iight reddish brown to 7.5 YR

• 6/2 pinkish gray dry and 5 YR 5/2 reddish gray to 2.5 YR 5/4 reddish brown wet). The till and massive lake sequenee eontain small amounts of silt, sand, gravel, and eobbles. Aeeording to well logs, the !ill rests di­,eetly on the Niagara dolomi te of Silurian age whieh is 40 to 80 feet below lake level. The till grades imper­eeptibly upward and laterally into the massive lake sequenee whieh, in turn, grades into rhythmieally bedded elay with some sil! and sand. The rhythmieally bedded deposits loeally extend from below lake level to as mueh as 20 feet above. The till and lake deposits represent !he Late Woodfordian glacial sequenee whieh was deposited probably between 14,000 and 12,000 radioearbon years ago.

Above !he rhythmieally bedded deposits loeally are layers of yellow-brown sand and gravel from a few inehes to 4 fee! thiek. They are considered shallow water, near shore, and beaeh deposits resulting from wave and eurrent aetion on the underlying deposits. The buried forest (Figs. 8-10) rests on and is formed in !he beaeh and lake deposits. The buried soil profile varies markedly aeeording to whether it is developed in the rhythmieally bedded clayey sequenee or in the eoarser sands and gravels. The forest horizon ranges gen­erally from 1 ineh to 12 inehes in thiekness, but loeally is cut out. It is undulating in the bank (Fig. 7), in part related to genUe knob and swale topography on whieh !he soil formed and in part due to warping by Ihe overriding Valderan ice. Trees in it are radioearbon dated at 11,840 years B.P. (Broeeker and Farrand, 1963). The most mature tree, aeeording to published information, has 142 growlh rings. AlI the larger pieees of trees

89

22

and stumps in the shelter are spruce (B. F. Kukachka, Forest ProducIs Lab., Madison, Wis.). While spruce eories are common in the plant debris.

On top of the forest bed are Iighl yellow to dark yellow lake sands, fine to coarse in texture. Locally, red colors are presenl. The sands are a few inches to 6 feel thick, bul locally are also absent. They contain numerous fragments of organic matler and portions of reworked soil. They are considered lo be the resul! of lhe rising lake level in front of Ihe advancing V.lders ice.

On top of them rests 2 to 12 feet of red (5 YR 6/3 Iighl reddish brown dry lo 2.5 YR 5/4 reddish brown wet) clayey liII of Valderan age, estim.led at 10,000 lo 11,500 radiocarbon years B.P. The till contains por­tions of the soi! and logs incorporaled from the buried soil, and local patches of sand incorporated from lhe lake deposits above and below the foresl soi!. Vertical prismatic fracture is pronounced in exposed cliffs in marked contrasl to the Late Woodfordian lill.

Local lake accumulations consisling of massive lo well-bedded sands are found on top of the till. They are as much aS 4 feet thick. The finer porlions are cornmonly red sill and very fine sands from the reworked Valders till; Ihey are inlerstratified with coarser yellow-brown sands and sorne gravel. Presumably they were laid down during the waning of the Valderan ice. A modero soil disrupted by plowing is formed in the Valderan till and in local patches of the youngest lake sands.

Woodfordian border

• Twocreekan organic matter in burlad deposit, wilh aga in radiocarbon years. ,

Flg. 19

90

23

TWOCREEKAN RADIOCARBON DATES SHOWN ON FIGURE 19

Date County Sample No. Material Remarks

12,800±220 Jefferson WIS-48 Spruce In basal peat

12,410±lOO Ozaukee WIS-347 Tamarack In basal peat

ll,560±350 Dane W-2015 Tamarack In basal peat

ll,611±600 Sauk M-812 Charcoal In fire pit

ll,130±600 Jackson W-1391 Wood In sand under peat in meander scar

12,800±400 Waushara UCLA-632 Organic 4 feet aboye bottom of kettle

12,OOO±500 Waushara W-641 Peat Under lake clay-silt

12,220±250 Waushara W-762 Peat Under lake clay-silt

12,060±700 Winnebago W-1l83 Peat and spruce Under till

11,790 Average Outagamie L698D Spruce Under till

11,840 Average Outagamie L698B • Spruce In buried soil

ll,640±350 Outagamie W-l110 Tamarack In buried soil

11,840 Average Manitowoc L698C Wood 6 to 12 inches below buried soil

ll,140±300 Brown W-590 Wood Under till

ll,940±390 Brown Y-147x Wood Under till

12,200±350 Shawano W-2357 Spruce With pond depo;its

12,900±300 Vilas 1-3780 Organic Basal lake deposits

DESCRIPTION OF THE BURIED SO/L

The buried soil is generally only a fey¡ centimeters thick, varying locally apparently in degree of develop­ment because of former topography, moisture, and texture of material, and in part by truncation from subsequen! rising lake waters. An incipient Podsol, with impeded drainage (Udorthent) similar to that under northern coni­fers in sorne wetlands today, typifies much of the soil on former knobs; in bogs and swales transported organic litter is characteristic.

A typical sequence Ihat represents a fairly thick profile a! one point at the shelter follows (Hole, 1967):

Depth Below Surface cm

IIOlb 492-494

IIAlb 494-498

IIA21b 498-505

IIA22b 505-525 and Bhirb

IIClb 525-535

Black (lO YR 211, moisO mucky peat; weak fine platy, plates consisting of dense mat of organic fibers and shreds, including twigs and rools; friable; medium acid (pH 6.0); abrupt wavy boundary. (O to 1 cm thick.)

Black (lO YR 2/D silt loam to muck; massive to strong fine platy; friable; medium acid to moderately alkaline (pH 6.0 to 8.0), with effervescence of discrete particles when f100ded with dilu!e HCl; abrupt wavy boundary.

Gray to light gray (lO YR 5/1-7/D fine sandy loam; with distinct to prominent, few medium motiles of dark yellowish brown to yellowish brown (lO YR 4/4-5/6). These occur adjacent to joints or crack s in the substratum; sorne of the brown-coated joints extend clear through Ihe solum in place s, up inlo the overburden; massive; friable; calcareous; abrupt wavy boundary. (5 lo 15 cm thick.)

Grayish-brown to gray (lO YR 5/2-5/D fine sandy loam with 15% of surface, particu­larly along joints, occupied by prominent coarse motUes as described aboye; locally a gravelly sand loam; massive; friable; calcareous; clear smooth boundary. (15 lO 30 cm thick,)

Grayish-brown (lO YR 5/2) silt loam and fine sandy loam wilh sorne pockets and seams oC gravel; iron stains along joints, as described aboye, but somewhat fewer~ massive¡ friable; calcareous.

91

24

Particle size, free rerríe oxide, and calcium carbonate equivalent are shown in Table 1 fOI another buried profile near the shelter, and for eomparison with the modern soil aboye it.

O. B. Lee and F. D. Hole (1970, ms.) elassify the buried soil as a typie Udorthent.

"The modern soils in the eultivated field are naturally well drained, developed in 15 to 75 cm of loamy covering over Valders till, and inelude two phases of the Hortonville loam, a Oray-Brown Podzolie tran­sitional to Podzol. On rises is a weakly developed bisequal soil (Alfie Haplorthod of the new elassinea­tion system: Soil Survey Staff, 1960, 1967) in whieh a Podzol soi! profile is faintly developed in the mid­die of the A horizon of a somewhat degraded Oray-Brown Podzolie (Alfie Haplorthod). In slight depres­sions the ineipient Podzol is not present and the surfaee soil (Ap horizon) is relatively thiek and dark (Mollie OlossudaIO."

A profile of the modero soi! follows (O. B. Lee and F. D. Hole, 1970, ms.):

Soil Profile Hortonville loam, dark surfaee variant.

Ap 0-25 cm Blaek (10 YR 2/1 moisO and grayish-brown (10 YR 5/2 dry) loam; modera te medium granular strueture; friable moist; neutral to alkaline; abrupt boundary.

A2 25-36 cm

Bl 36-46 cm

IIB2t 46-71 cm

IICI 71-102 cm

II C2 102-224 cm

Brown (10 YR 5/3 lnoisO and pinkish-gray (7.5 YR 6/2 dry) fine sandy loam; weak medium platy strueture; plates break into weak medium subangular bloeky aggregates; patehy, yellowish-brown (10 YR 5/2 dry) stains on ped surfaees; friable moist; a few pebbles; alkaline; elear boundary.

Brown (7.5 YR 5/4 moist) and Iight brown (7.5 YR 6/4 dry) silt loam; moderate, fine to medium, subangular bloeky strueture; pinkish-gray eoatings on ped faces; slightly sticky wet, hard dry; alkaline; elear boundary.

Reddish-brown (5 YR 5/3-4/3 moist) elay loam; moderate, eoarse prismatie strueture, prisms break into strong, medium angular bloeky peds; sticky wet, hard dry; a few peb­bies; alkaline;' elear boundary.

Reddish-brown (5 YR 5/3 moisOloam to elay loam; moderate, eoarse prismatie struc­ture; prisms break into moderate, medium, angular bloeky peds; stieky wet, hard dry; a few, mainly dolomi.tie, pebbles and eobbles; ealeareous matrix; gradual boundary.

Reddish-brown (5 YR 5/3 moisO elay loam; eoarse prismatie strueture; prisms break into eoarse bloeky peds; light brownish-gray (2.5 YR 6/2 moist) coatings on vertical faces of prisms. These eoatings effervesee strongly in dilute acid; ped interiors effer­vesee moderately; a few, mainly dolomitie, pebbles and eobbles; abrupt boundary with underlying pro-Valderan mud flows.

92

. Table 1. Some anaIytieaI data for two soils at tbe Two Creeks Site, Manitowoe Count¡y, Wisconsin'

MODERN SOIL

Hortonville loam, dark suJt'face variant (Mollie GlossudaIf')

P. S. Dislribution' Horizon & Depth (cm)

G' S' Si' C' Free CaCO,

------------------- % -----~~~~--_:~~~:-O (0.541)

Ap (0-25)

A2 (25-36)

B1 (36-46)

HB2t (46-71)

HC1' (71-102)

IVCS" (368-406)

o 35

Ir. 60

N.O. N.O.

Ir. 31

16- 39

O 28

'Data from Lee and Hole (1970)

47 18 1.52 O

24 16 0.58 O

N.O. N.O. N.O. O

34 35 1.69 O

36 25 0.67 40

60 12 0.45 57

2Classification according to the new soil classification system of the V.S.D.A. (Soil Survey Staff, 1960, 1967)

lParticle size distribution 'G = gravel (2.0 mm dia.); nol included in tbe sum of s, si, and c which total 100%

BURlED SOIL

Twoereekan peat¡y loaro, buried variant (Fibristie Udortbent')

P. S. Dislribution' G' S' Si' C' Free CaCO, Horizon &

Depth (cm) '" Fe,O, equiv. ------------------- ~ -----------------VOb (406-414)

. VlBgb (414-434)

VlC1b (434-440)

VlIC4b'" (460-4801

10

Ir.

10

39

82

s

'S' = sand (241.05 mm dia.> 'Si = silt (0.0541.002 mm dia.) 'c = clay (0.002 mm dia.) 'Valders till 'Pro-Valders mud f10w "Glacial Lake Chicago deposits

41 20

11 7

64 31

N.O.

0.51

0.22

0.83

N.O.

35.2

42.0

34.0

.. <lO

26

DETAILS FROM EARLIER STUDlES

Because the earHer literature on the Two Creeks site is not widely available) sorne extracts and sum~ maries are presented here.

Goldthwait (1907. p. 61) wrote: "Two miles south of the village of Two Creeks (in seetion 24) the freshly cut lake eliff showed in July. 1905. a remarkable eross-section of an interglaeial fores! bed. Laminated red elays formed the base of the seetion. up to Iwo or three feet above the water. Above this. and separating it from a twelve-foot sheet of stony red till. was a eonspieuous bed of peat, stieks. logs and large tree trunks. whieh unmistakably represent a glaeiated forest .... The till immediately above the forest bed. besides eontain­ing eharactedstic subangular striated stones and red elay similar to the clay in the stratified beds below. all absolutely unassorted. was plentifully mixed with broken branches and twigs. In the underlying forest bed the stumps were well preserved. the wood being soft and spongy Iike rotten rubber. but retaining all the appearanee of its original strueture. Several logs and stumps lay pointing signifieanUy towards the southwest. the direc­tion in whieh the ice sheet probably moved at this place. One Iittle stump, however .... with its ramifying roots firmly fixed in the laminated red e1ays, stood ereet as when it grew there. but it had be en broken short off at the lop. where the ice sheet. dragging its ground-moraine along. had snapped off the top without uprooting the tree. Around eaeh root the red clay was discolored to a Iight drab. showing the effeet of acids derived by de­cayo in contact with the iron-bearing elays. There was no mistaking the only half-exeavated eondition of Ihe deposito Clearly this surfícial sheet of red till reeords a final advance of the ice sheet over a surface of lam­inated red e1ays. which here. at least. had be en clothed with a foresl. The trees were broken and generally overturned by the ice. and buried beneath the twelve-foot sheet of till. The wonder is that so much of the over~ridden forest should be preserved, and at leasl one stump in it rema in erect."

Goldthwait (1907. p. 59) also mentioned that at one point in the vicinity of Manitowoe a peal bed 3 feetlhick formed the upper part of the 10-fool,cliff. with laminated clays eontaining sticks and branehes be­low. In another place a bed of old logs and sticks ¡ay buried beneath 15 feet of clay. near the base of the cliff. Thus were recorded. in parto the location and descriplion of !wo segments of the Two Creeks Forest Bed.

No immediate study was made ofthe foresl bed although F. T. Thwaites visited the are a several times between 1922 and 1930. Wilson (1932) undertook a preliminary investigation and later amplified his work (Wilson.1936). He fírst studied the for"st,bed where it'was exposed for one-half mile along the lakeshore in sections 11 and 13. T 21 N. R 24 E. He al so mentioned that the same forest bed was exposed three miles to the north on the lakeshore and in a ravine about a quarter of a mile to the west in seetion 35. T 22 N. R 24 E. Kewaunee County.

Wilson (1932) studied closely the foresl bed for only about 100 feet along the lakeshore and through a vertical range of only several inches. He interpreted the fores! bed lO Iie 00 top of varv~d clays and sills and under additional laeustrine sil!s and sands deposited between the relreat of ice and its re-advance whieh laid down till on topo Locally the lake beds were 12 feet thiek. The till on top of the laeustrine sediments was about 8 feet thiek. At the site most of the wood is spruee (Picea mariana and Picea canadensis [glauca]) and hemloek. The wood is soft and easily broken and ehecks ana breaks into short seetions on drying. Tis­sues, however, are not destroyed and microscopic sections can be rnade of them. Where wood and peal are in contaet with the red till. there is a zone in the elay a few inches wide of greenish-gray color due to deoxida­tion of the iron. The logs oecur most frequenUy in the lacustrine sediments direeUy above the forest bed. but are al so in the overlying till. Wilson found one stump in silu with the butt of the broken log almost attaehed. The roots of this stump extended along the forest bed peat. On a portion of the root that had be en exposed above the ground during the interstadial period was found a braeket fungus. It is Polyporus but the speeies was not determined. AII the logs that had not been broken by subsequent handling showed ,agged splintered ends as a consequence oC glacial action.

Wilson (1932) studied the growth rings in seetions of six logs. The greatest number of rings in on. see­tion was 82; the average was about 60. Five of the logs showed by the width of suceessive ríngs a marked deerease in therate of growth in their last 12 years of !ife at the Two Creeks site. One log taken from lhe red till direeUy above the foresl bed showed IitUe deprease until the last year of its growth. That particular log was white spruce (?). Picep canadensis [glaucal. The first 5 logs were eonsidered by Wilson to represent the growing eonditions of the forest bed al the site. whereas the log taken from the till above was eonsidered as having be en Iransported by ice from a different environment farther north. When the log taken from the red till was eompared with the others. an extreme differenee in size and growth rate was notieeable. That log was twieé the diameter of any of the others although it had only the average number of growth rings. The width of

94

•

27

the rings did not agree with that of the forest bed trees. The growth rings could not be compared exactly with reference to particular years, because it was not

kno~n whether all the trees were destroyed in the same year or whether they were all alive at the time the ice adv.nced. However, Wilson considered il probable that the largest lag having been brought in by the ice was felled several years befare the trees that had grown at the site studied.

Detailed study of wood sections by Wilson showed that certain small rings of the forest bed trees oc­curred at years approximately corresponding to those in which wide growth rings occurred in the transported lag from the overlying till, and vice versa. Ir excessive moisture was one of the primary factors for small growth lÍngs in the trees, as is suggested by the character of the flora and fauna, then trees growing in higher ground would not have been similarly affected and probably would do better in wet years.

The moss f100r of the forest bed contained the most extensive group of plants found in the remains. The moss material, identified by L. S. Cheney, was divided into 19 species. AII the mas ses are of existing spe­cies but are in general more northerly in their modelO distribution than the Two Creeks Foresl Bed location. Nearly all are found in northern Wisconsin but the present southern Iimits of a rew are in Canada.

Peat in the forest bed was poorly formed and in some parts of the exposure was wanting entirely. Wilson (1932) concluded from this, as well as from some other organic remains, that the Two Creeks Forest Bed was not exactly a lowland forest but rather a dry forest at one stage of ils existence. In place s the mas ses and other plant remains accumulated as a silty peat such as can be found in any spruce forest today. 11 is from this peat that the microfossils were secured.

Seven species of mollusks were identified from the forest bed by F. C. Baker to whom Wilson sent speci­mens. These were from three levels in the forest bed. They agree ecologically with other organic remains from their respective horizons. One Pleistocene form was reported-from the clay immediately beneath the forest bed. The individual,s in higher levels represented existíng species.

The mollusk Fossaria dalli (Baker) was considered Pleistocene on the basis of its large size. lis habitat was wet mud above water. Two other species of mollusks, Pupilla muscornn (Linn.) and Succínea avara (Say.), both represent forestforms and suggest arrival of trees at the same time as a few grasses and mOSses. Direct­Iy on the ~urface of the clay occurs a mixture of spruce cones,needles and forest mosses. Mixed with the mosses are shells of land mollusks Succinea avara and Verligo venlricosa (Morse). One moss was peculiarly restricted to the lowest level of the forest bed. This is Bryum cyclophyllum (Schwaegr.)-a forest form that seems to have been first to establish ilself on the Two Creeks forest f100r. Other plants in this horizon repre­sented only by a few palien grains and spores are grasses, heaths, birch, Jack pine (Pinus banksiana Lamb.) and a species of Asplenium. Fungi were abundant; sorne were Beheos and athers were representative of Dema/icae. Dark beetle excavations were found on the logs and may represent two genera.

Culberson (1955), with the aid of W. C. Steere, found eight species of mosses that are associated wilh floras of more northern affinities.

Wilson ([932 and 1936) thus recorded an early phase with aquatic and semi-aquatic mollusks, an inter­mediate phase with moist to dry woodland mosses, and a final phase of f100ding with aquatic mollusks and mosses. The pollen spectra in Figure 20 by West (1961) and Schweger ([966) give additional details of the vegetational changes during Twocreokan time. See also Schweger (1969) and Maher (Geol. Soco Amer. Field Trip Guide No. 4) for additional details on other siles. The abundance of Shepherdia canadensis (buffalo berry) pollen al the base of the sediments indicates early colonization by this shrub of the land surface ex­posed by the lowering of the lake level (West, 1961). Shepherdia canadensis is a Docthem .nd moun!ain plant found in forest clearings and on sandy shores particularly in the boreal spruce forests. Thus the plant' s be­havior at the beginning of the Two Creeks interval exactly parallels ils present behavior. The phase with Shepherdia was short Iived, and Picea forest succeeded the pioneer cornmunity as indicated by the high fre­quencies of Picea palien. White spruce dominated over black spruce. The f100ding of the forest litter by the upper sills was accompanied by a large decrease in pollen frequency. At the same time the NAP total, includ­ing Ambrosia, Arlemisia and other composiles, rises slightly. This may reflect the opening out of the regional forests associated wilh the Yalders re-advance, but then there is also the possibilily that some of the palien in lbe silts is secondarily derived.

The vegetation of the Two Creeks interval is clearly boreal in character. Originally Wilson ([932) com­pared ils clima te with that of northern Minnesota today. In his later paper (1936) he suggested that the climate was not necessarily as severe as this fo! the plants also represent pioneee organisms of denuded areas under cer~n conditions and are not reliable indicators of asevere climate. West (1961) finds the interpretation of the pollen profiles from this and other nearby sites to be complicated and open to more than one interpretation. He concludes, however, that the spruce forest was able to survive along the margin of the Yalders ice, al-

95

28

though with openings. At least the climate of Two Creeks -time was not necessarily much more severe than that of today in the area. Schweger (1966 and 1969) found only simple pioneering boreal wetland species presento Roy (1964) in a study of the Pleistocene non-marine mollusca of northeast Wisconsin concluded also that these species represented climates very similar to that of northem Minnesota today.

Pollen studies of other sites of Two Creeks age in Wisconsin have also' been done by West (1960, by Sehweger (1966 and 1969), and by olhers whose work has not be en published. Sehweger (1969) found distinc­tive differenees in the flora in Ihose sites where more time was available. Local variations in the forest Iitter and maerofossils at Ihese various Two Creeks loealions al so are appearing (Blaek, Hole, Maher, and Freeman, 1965, p. 68). No vertebrate remains have been found in dated Twocreekan material s in Wisconsin yet mast­odons in deposits possibly of that age and younger are known.

Wood fragments of Twocreekan age are espeeially common in the Valderan till, but locations in eastem Wiseonsin where Twoereekan soil profiles are in situ are less common (Fig. 19). Particularly good exposures have been seen in borrow pits in the SW 1/4 and NE 1/4, SE 1/4, seco 19, T 23 N, R 19 E, Outagamie County (PieHe, 1963). Another is in the SE 1/4, NW 1/4, seco 15; T 22 N, R 15 E. Detrital organic Iitter of Two­c.,eekan age in lacustrine sediments is found at several places, such as the SE 1/4, SE 1/4, seco 22, T 24 N, R 21 E, Brown County, and the SW 1/4, SW 1/4, seco 6, T 21 N, R 23 E, in Manitowoc County. AII these sites are in borrow pits, are of very Iimited extent, and do not lend themselves to use by the public. The type sec­Hon remains unique.

The controversy of the varve-dated chronology calling for Two Creeks to be 19,000 years old (Antevs, 1962) versus the radiocarbon dales of 11,840 years (Broecker and Farrand, 1963) requires that we examine in­formation available from much of northeastern United States and Canada as well as the European transatlantie correlations. This goes far beyond the scope of this papero Suffice it to say Ihat the radiocarbon-controlled chronology has bee~ accepted by a majority of workers.

1 1

... Tr ...

" ten "t~uo~

POLlEH OIAGRAM t::I DUC1\: CRtEK IIIOGE: $ITE aye.E.$CHwtOEIt

""" "'"' 'UK"" co"'~~~::.

l l """""'" """"""

.ll IoCblDQII!au ..

. ~ • • • • POU.EN OIAGAAM Of' TYPE TWO CRUKS ay ft. o. Wl:ST

Tr,"

• PcIItn P~1of\I

PolIen spectra of Two Creeks Forest Bed (Black, Holo, Mahee, and Freeman, 1965, p. 67, Fig. 5),

Flg. 20

96

'011." $\,,,, ,. .. lO

'" lO.

". • •• "" ••

29

CI4 14000+ 1350010 13000 12000 1100010 10500 10000+ 850010 4000 DATES 14000 12500 9500

Lake Loke Lokl Two Creek Lokl Lokl Lok. Lok. Lok. EASTERN LAKES Moum •• Ar kono Whlttle .. y low water Warrtn Gtonmer. Lundy Algonquln Nlpl •• lng

Hough's Grond Rlver Two eplsodes Firsll Second I ond I 01 greol GI.n- ........ · .. -wood Chgo.oullel Hough's Thlrd downwasllng

-r-- 640 Brelt'S\ Gle'nvlood

~ drY-7--~-d---~f Volders Ihln / Glenwoo I heel

LAKE 620 -ICAGO CH

ST

\ / ?

Brelz's I , .... c. s :Ic" I ~ Columel 2 '- -,,!!.9 gh's C~'~mel

\\ J,\ Bretz's Toleslon .i Hou9,!1's Toleslon AGES_SOO

Hough's

\?I 1nlro- GI.nwood 560 low woter

I I Sub-Woyne ,

Diagrarnmatic depiction oC two contrasting interpretations of fluctuations oC water level of Glacial Lake Oticago.

YEAIlS BEFORE THE PRESENT

t bostd on C-r4<folu)

o

2,500

3,500

5,000

6,000

11,000

LAKE STAGE IN THE LAKE MrCHIGAN

8ASIN (elev_ aboye seo l.ve'l

Loke Michigon

Ch;ppewa (2301

Poyette ond / relofed stoO" 01 ~Lower A10Ol\quln~ lokes o, Stanle)' (Oepll'l "om '09

~, poIltn ploMe ItlltIC"U)

AlgonQutn (6051

Toluton (6051

Calumel (6201

Bowmonvillt (below 5601

Glenwood (6401

Fig.21

I Ook·Pone

I Pon.

1 I

JockPin.

I I

Sprue ... Fir (de<:linil'l9)

SprUCt lir

WI$CON$IN CHRONOt.OG't

XEROTHERMIC

Ooen;ng 01 Notlh Soy Oullt!

lOE RETREAT

TWO CREEK INTERSTAOIAL

CARY

Radíocarbon years. lake Ievels. forest succession, and chronology in the Lake Michigan basin (Zumberge and Potzger, 1956, Fig, 4),

Flg. 22

97

30

CONCLUSIONS AND SIGNIFICANCE

When it is recognized that the forest bed is established on lacustrine sediments and yet covered by lacus­trine sediments all of which in turn lie between two tills, something of the magnitude of the glacial history inferred becomes apparent. To this we must add slill more lacuslrine sediments and windblown materials on lop of Ihe younger til! at the Two Creeks Foresl Bed locality. This means we must take into accounl at least Ihree lakes whose levels have be.n up to a poinl more Ihan 30 feet higher than that oC present Lake Michigan. One lake followed the basal till, ooe swamped the forest bed horizon, and one carne in on top of the younger till. These f1ucluations are oC an order of magnilude beyond that which can be achieved merely by increasing preeipilation. Changes in the oullet or oullets of Lake Michigan were involved. We cannOI confine our analy­sis oC this problem only with a study of Lake Michigan. Several oC the Greal Lakes (Hough, 1958) musl be taken into accounl and their slory integrated with Ihe Pleistocene history oC Ihe St. Lawrenee, Hudson, and Mississippi river valleys. For convenience of the reader, a diagrarnmatic depiction of two contrasting ¡o ter­prelations of flucluations of waler level of Glacial Lake Chicago are recorded in Figure 21. The differences of opinion oC interpretation of field data betweeo Bretz (1959, 1964 and 1966) and of Hough (1958, 1963 and 1966) are by no means resolved. Black wDuld agree with Bretz (1966) thal s lake level at 620 feel (equal to Ihe level slong Highway 42 al Two Creeks, Fig. 5) was posl-Valders farther south, near Port Washinglon. lt seems likely thal the lake sands on the Valders lill al Two Creeks are local in occunence, bul a Calumel or olher level of Glacial Lake Chicago has nol yel been ruled oul. Discussion of Ihis problem goes beyond Ihe scope of Ihis parlicular paper and ineludes glacial lakes and drainage in oorlhero Uniled States and in Canada from Ihe Rockies to Ihe Allanlic and from Hudson Bay lo lhe Gulf of Mexico. It even involves indireclly Ihe arguments of Anlevs (1962) (cf. Hughes, 1965) on Iransallantic·conelalions and daling. Although complex, Ihe hislory of Ihe Greal Lakes is lruly a fascinaling subjecl (Hough, 1958).

Precise conelation of Ihe age of Ihe litl al Ihe base of Ihe cliff has nol been made. lt is certainly Lale Woodfordian, possibly a younger unil of Ihe Cary or subsequenl slighl re-advance such as Ihe Mankato or Porl Huroo of olher slales. The lill locally is gray bul Black has found mostly red al Ihe site. Gray drifl is sup­posealy· characlerislic of ¡he Port Huron of Michigan (Wayne and Zumberge, 1965), whereas red driCt Ihat is ·posl-Cary and pre-Two Creeh is gene rally considered representalive of the Mankalo of Minnesota (Wright and Ruhe, 1965). The Port Huron moraine (Wayne and Zumberge, 1965,p. 72) was described by Toylor (Leve re ti and Taylor, 1915, p. 293) as "one of Ihe b.l'st developed and mosl clearly defined moraines in Ihe Greal Lakes region" and Ihis slalus has been accorded Ihis moraine by every glacial geologisl who has worked in Michi­gan since thal time. The Port Huron moraine was daled by Hough (1958, p. 278) al 13,000 years ago. It was cOHelated aCross Lake Miehigan by Thwailes and Berlrand (1957, Fig. 1) with an unnamed moraine near She­boygan, Wisconsin. lf lrue, Ihen presumably Ihe Porl Huroo would extend to the norlh and encompass the Two Creeks sile. However, neIV data from Michigan disproves sorne of these findings (Farrand, Zahner, and Benninghoff, 1969). A Cary-Port Huron ¡nterstade wilh lundra plants is dated al 12,500 to 13,000 years B.P. and Hes belween Iwo red-brown sandy lills previously conelated wilh Ihe Valders.

If Ihe above conelalion is coneel Ihal Ihe basal litl al the Two Creeks Foresl Bed is of Porl Huron equivalenl, then Ihe hislory of Ihe lake sequence would begin al aboul 12,000 lo 13,000 years ago. Pollen speelra and chronology of Lake Michigao waler levels from the Michigan side are shown in Figure 22 for Ihal lime lO Ihe presenl. Stumps and olher organic maller in situ are lo be found al varíous deplhs below Ihe waler of Lake Michigan, adding lo our knowledge of Ihe low waler levels (e;g., Somers, 1968, who reporls slumps in growlh position al a deplh of 32 feel and 6,700 radiocarbon years old in Ihe Slrails of Maekinacl. Thwailes and Berlrand (1957) summarize Ihe meager informalion 00 lake levels in Ihe Two Creeks area. Obviously more delaited sludies musl be done before a elearer pielure can be obtained.

When one eonsiders Ihe magnilude of waler flucluations Ihrough hundreds of feel during ooly sorne Ihou­sands of years, Ihe presenl-day flueluations of a few feet are relatively insignifieant. Nonelheless, exeeed­ingly rapid shoreline erosion (up lo 40 feel per year al Manilowoc in 1905) (Goldlhwail, 1907), forees one lo appreciale sorne of Ihe eonsequenees of minor lake-level fluclualions. Al Ihe presenl lime, waler levels in Lake Miehigan are high after having be en ¡ow for many years. As a result, shoreline eros ion al Ihe Two Creeks Foresl Bed has been minimal unlil Ihis pasl year. When Ihe sile was firsl found by Goldlhwait and Ihen subsequently when Wilson had opporlunity lo examine Ihe loealion, waler levels also were relalively high. This pennitled shore erosion lo expose Ihe foresl bed whieh then was covered for deeades by slump and vegetation.

98

REFERENCES CITED

Alden, William C., 1918, The Quaternary geology of southeastern Wisconsin: U.S. Geol. Survey Prof. Paper 106, 356 pp.

Alden, William C., 1932, Glacial geology of the central states: XVI lnlem. Geol. Congress Guidebook 26, Excursion C-3, 54 pp.

Antevs, Erost, 1962, Transatlantic climatic agreement versus C 14 dates: Jour. Geol., v. 70, pp. 194-205. Black, Robert F., 1966, Valders glaciation in Wiseonsin and Upper Michigan-A Progress Report: Pub. 15,

Great Lakes Res. Div., Univ. of Michigan, pp. 169-175. Black, Robert F., Clark, David L., and Hendrix, Thomas E., 1968, Two Creeks Buried Forest Project - CIC

Instructional Improvement Program: Jour. Geol. Ed., v. 16, pp. 139-140.

39

Black, Robert F., Hole, Francis D., Maher, Louis J., and Freeman, Joan E., 1965, Guidebook for Field Confer­ence e - Upper Mississippi Valley: Intem. Assoc. for Quaternary Research, VJlth Congress, Nebraska Acad. Sciences, Wiseonsin portion, pp. 56-81.

Black, Robert F., and Rubin, Meyer, 1967-68, Radiocarbon dates of Wisconsin: Wis. Acad. ScL, Arts, and Letters, v. 56, pp. 99-115.

Bretz, J. Harlen, 1959, The double Calumet stage of Lake Chicago: Jour. Geol., v. 67, pp. 675-684. Bretz, J. Harlen, 1964, Correlation of glaciallake stages in the Huron-Erie and Michigan basins: Jour. Geol.,

V. 72, pp. 618-627. Bretz, J. Harlen, 1966, Correlation of glacial lake stages in the Huron-Erie and Michigan basins: Jour. Geol.,

v. 74, pp. 78-79. Broecker, Wallace S., and Farrand, William R., 1963, Radiocarbon age of the Two Creeks Forest Bed, Wiseon­

sin: Geol. Soco Amer. Bull., v. 74, pp. 795-802. Chamberlin, T. C., 1877, Quatemary Forroations - the drift: Chapo V, pp. 199-246, in Geology oi Wisconsin,

V. 2, 768 pp. Commissioners of Public Printing. Chamberlin, T. C., 1878, On the extent and significance of the Wiseonsin ketUe moraine: Wis. Acad. Sci.,

Arls, and Letters, Trans., V. 4, pp. 201-234. Chamberlin, T. C., lÍl83, Terminal moraine of the second glacial epoeh: U.S. Geol. Survey Third Annual Re­

port, pp. 291-402. Culberson, W. L., 1955, The fossil mosses of the Two Creeks Forest Bed of Wiseonsin: Amer. Midland

Naluralist, v. 54, pp. 452-459. Farrand, William, Zahner, Robert, and Benninghoff, William S., 1969, Cary-Port Huron Interstade-evidence

from a buried Bryophyte hed, Cheboygan County, Michigan: Geol. Soe. Amer., Spec. Paper 123, pp. 249-262.

Fenton, Carroll Lane, and Fenton, Mildred Adams, 1952, Gianls oi geology: Doubleday and Co., 333 pp. Frye, John C., and Willman, H. B., 1960, Classification of lhe Wiseonsinan Stage in the Lake Michigan gla­

cial lobe: Ill. State Geol. Survey Circo 285, 16 pp. Frye, John C., Willman, H. B., and Blaek, Robert F., 1965, OuUine of glacial geology of Illinois and Wiscon­

sin: The Qualemary oi Ihe Uniled Slales, H. E. Wright, Jr., and David G. Frey, editors, Princeton Univ. Press, pp. 43-61.

Frye, John C., Willman, H. B., Rubin, Meyer, and Black, Robert F., 1968, Definition of the Wisconsinan Stage: U.S. Geol. Survey Bull. 1274-E, 22 pp.

Gaenslen, George, 1969, A trip on glacial geology in the North KetUe Moraine area: Lore, v. 19, no. 3, pp. 85-97.

Goldthwait, James W., 1907, The abandoned shore lines of eastern-Wiseonsin: Wis. Geol. Survey Bull. 17, 134 pp.

Hole, Froncis D., 1967, An aneient young soil: Soil Survey Horizons, v, 8, no. 4, pp. 16-19. Hole, Francis D., and Beatty, M. T., 1968, Soils of Wisconsin, overlay map on 1:250,000 U.S. Geol. Survey

topographic quadrangles: Wis. Geol. and Na!. Hist. Survey. Hough, J. L., 1958, Geology oi Ihe Greal Lakes: Univ. Ill. Press, 313 pp. Hough, J. L., 1963, The prehistoric Great Lakes of North America: Amer. Scientist, v. 51, pp. 84-109. Hough, J. L., 1966, Correlation of glaciallake stages in the Huran-Erie and Michigan basins: Jour. Geol.,

v. 74, pp. 62-77. Hughes, O. L., 1965, Surfieial geology of part of the Coehrane district, Ontario, Canada: Geol. Soc. Amer.

Spec. Paper 84, pp. 535-565.

99

40

Lawson, P. V., 1902, Preliminary notiee of the forest beds of the Lower Fox, Wiseons,n: Nat. His/. Soco Bull., v. 2, pp. 170-173.

Lee, G. B., and Hole, F. D., 1970, Modem and buried soil profiles at the Two Creek Forest'Bed site, Mani­tOWQC County, Wisconsin: ms.

Lee, G. B., Janke, W. E., and Beaver, A. J., 1962, Partiele-size analysis of Valders drif! in eastem Wiseon­sin: Sci., v. 138, pp. 154-155.

Leverett, Frank, .nd Taylor, F. B., 1915, The Pleistocene of Indiana and Michigan and Ihe history of the Great Lakes: U.S. Geol. Survey Mon. 53, 529 pp.

Murray, R. C., 1953, The petrology of the Cary and Valders tills of northeastem Wisconsin: Amer. J. Sci., v. 251, pp. 140-155.

National Park Serviee-Wiseonsin Department of Natural Resourees, 1968, A eomprehensive plan for the Ice Age National Scientific Reserve, Wisconsin: Spec. Pub., 61 pp.

Owen, D. D., 1852, Report of a geological survey of Wisconsin, Iowa, and Minnesota: Lippincott, Grambo & Co., Philadelphia, 638 pp.

Piette, Carl R., 1963, Geology of Duck Creek Ridges, east-central Wisconsin: The Univ. of wis., M.S. thesis, 86 pp.

Prouty, C. E., 1960, Lower Paleozoic and Pleistocene stratigraphy across central Wisconsin: Mich. Basin Geol. Soc., 34 pp.

Roy, Edward C., Jr., 1964, Pleistocene non-marine Mollusca of northeastem Wisconsin: S/erkiana, no. 15, pp. 5-75.

Schweger, Charles E., 1966, Pollen analysis of lola bog and paleoecology of the Two Creeks interval: The Unív. of Wis., M.S. thesis, 41 pp.

Schweger, Charles E., 1969, Pollen analysis of Iola bog and paleoecology of!he Two Creeks Forest Bed, Wis­consin: Ecology, v. 50, pp. 859-868.

Soil Survey Slaff, 1960, Soil classification, a comprehensive system, 7th approximation: U.S. Dept. of Agricul­ture, Govemment' Printing Office, 265 pp.

Soil Survey Staff, 1967, Supplement to soi! classification system: U.S. Dept. of Agriculture, Govemmen! Printing Office, 207 pp.

Somers, Lee H., 1968, A research dive in the Great Lakes: Umnos, v. 1, no. 2, pp. 2-5. Sultner, Lee J., 1963, Geology of Brillion Ridge, east-central Wisconsin: The Univ. of Wis., M.S. thesis,

99 pp. Thwaites, F. T., 1943, Pleistocene of part of northeastem Wiseonsin: Oeol. Soco Amer. Bull., v. 54, pp.

87-144. Thwaites, F. T., 1953, Field guide, Friends of the Pleistocene: Mimeo, 26 pp. Thwaites, F. T., and Bertrand, Kenneth, 1957, Pleistocene geology of the Door Peninsula, Wisconsin: Oeol.

Soco Amer. Bull., v. 68, pp. 831-880. Wayoe, William J., and Zumberge, James H., 1965, Pleistocene geology of Indiana and Michigan: in Qua/er­

nary of the Uni/ed Sta tes, Princeton Univ. Press, pp. 63-84. West, R. G., 1961, Late- and postglacial vegetational history in Wisconsin, particularly changes associated

with the Valders readvance: Amer. Jour. Sci., v. 259, pp. 766-783. White, George W., 1964, Early description and explanation of kettle holes: Jour. Olac., v. 5, pp. 119-122. Whittlesey, Charles, 1860, On the drift cavities, or "potash kettles" of Wisconsin: Amer. Assoc. Advance­

ment ScL, Proc., 13th meeting, 1859, pp. 297-301. Whittlesey, Charles, 1866, On the fresh-water glacial drift of the northwestern states: Smithsonian Con/ro

Knowledge, No. 197, 32 pp. Wilson, L. R., 1932, The Two Creeks Forest Bed, Mimitowoc County, Wisconsin: Wis. Acad. Sci., Arts and

Letters Trans., v. 27, pp. 31-46. Wilson, L. R., 1936, Further fossil studies of the Two Creeks Forest Bed, Manitowoc County, Wisconsin:

Torrey Bo/. Club Bull., v. 66, pp. 317-325. Wright, H. E., Jr., and Ruhe, R. V., 1965, Glaciation of Minnesota and Iowa: in Qua/emary of /he United

Sta/es, Princeton Uni;". Press, pp. 29-41. Zumberge, James H., and Potzger, John E., 1956, Late Wisconsin chronology of !he Lake Michigan basin cor­

related with poli en slUdies: Oeol. Soco Amer. Bull., v. 67, pp. 271-288.

100

Geological Society oC America Special Paper 251

1990

Radiocarbon confirmation of the Greatlakean age oi the type Two Rivers till of eastern Wisconsin

Allan F. Sehneider Department 01 Geology, Uni~ersity 01 Wisconsin-Parkside, Kenosha, Wisconsin 53141

ABSTRACf

Three radiocarbon dales on wood, including one on a 10g from Ihe Iype seellon of Ibe Two Riyers till, show Ihal Ihe age of Ihis liU unil is unqueslionably Greallakean (post-Twocreekan).

The Two Rivers liII, now formally designaled Ihe "Two Riyers Member of Ihe Kewaunee Formation," was named in 1973 by Eyenson for flne-grained reddlsh-brown 1m found along Ihe Lake Miehigan shore north of Two' Rivers, Wiseonsln. The 1m was eorrelaled wllh tiII of similar Ulhology Ihal oyerlles Ihe Two Creeks Foresl Bed al Ihe Two Creeks type seetlon, and Ihus Ihe till was eonsldered posl-Twoereekan (Greal­lakean) in age. Unlike Ihe age oflhe Valders liU, whlch has been hotly debaled (whelher pre-Twocreekan or posl-Twocreekan) during Ihe pasl 15 years, Ihe age of Ihe Two Riyers liII has nol been Ihe subjecl of direcl conlroversy. However, Ihe age of Ihe Two .Rivers liU al lis type locality has nol prevlously been demonslraled by radiometrlcally . daled malerial.

Part of a large log enclosed in tlU was colleeled from Ihe Two Riyers Iype seclion In 1968, aboul Ibree years before Evenson began his invesligalions in Ihe Twin Rivers lowland, bul Ihe exlslence of Ihls sample remalned generaUy unknown. The wood has now been daled al 11,910 ± 120 yr B.P. (ISGS-I058), Ihus proying Ihal Ihe 1m is younger Ihan Ihe Two Creeks Forest Bed from which Ihe log musl have been derived by ~~ .

Two addilional dales, from asile on Ihe soulh slde of Kewaunee, also serve as eonflrmlng dales for Ihe Greallakean age of Ihe Two Rivers liII. Wood from a blaek, snall-rieh peal layer has been daled al 11,700 ± 110 (ISGS-I061) and 11,650 ± 170 (ISGS-I234) yr B.P. The organie layer underlies flne-grained reddlsh-brown 1m Ihal has been eorrelaled with similar liU Ihal overlles Ihe Two Creeks Foresl Bed al ils Iype seclion and Ihus was calIed Two Rivers tiII by Aeomb and olhers (1982).

INTRODUCTlON

The fine-grained reddish-brown till units of eastem Wiscon­sin, commonly caUed the red c1ayey tills, have long been the subject of study and debate. Initially interpreted by Chamberlln (1877) as laeustrine sediment, the "Red Clay" was later correctly identified as till by Alden (1906, 1918) and other workers.

During the past 15 years, controversy over the red tills has focused mainly on the distribution, age, and correlation of the Valders till ofThwaites (1 943)-more specifically, whether that till is pre-Twocreekan or post-Twocreekan in age. Consideration of the age of the Valders tiIl, however, necessarily involves con-

sideration of other red till units, particularly the Two Rivers till of Evenson (1973a, b), whieh was regarded by Thwaites and Ber­trand (1957) to be part of the Valders till. The details of the debate conceming the age and correlation of the Valders and Two Rivers tills need not be reviewed here, inasmueh as those details haye been summarized weU in a number of fairly recent publlcations (e.g., see Blaek, 1980; and Acomb and others, 1982).

The purpose of this ehapter is to consider three radiocarbon dates on wood samples from eastem Wisconsin that demonstrate !he age of the Two Rivers till to be unquestionably Great-

Schneider, A. F., 1990, Radiocarbon confirmation oCthe Greatlakean age oCthe type Two Rivers till of eastem Wisconsin, In Schneider, A. F., and Fraser, G. S" eds" Late Quatemary hislory oC the Lake Micbigan basin: Boulder, Colorado, Geological Society of America Special Paper 25(,

101

52 A. F. Schneider

lakean-that is, post-Twocreekan. Two of these dates have beeo cursorily reported elsewhere (Sehneider, 1984; Liu and others, 1986, p. 131). One ofthe dated samples was collecled from Ihe type section of the Two Rivers till, and lhe resultant date repre­sents the fírst and only radiometric dale on material from the Two Rivers type locality.

RECOGNITION AND CORRELATION OF THE TWO RIVERS TILL

The name "Two Riveis till" was proposed by Evenson (1973a, b) for fine-grained reddish-brown till found along the Lake Michigan shoreline north ofTwo Rivers, Wisconsin (Fig. 1). More recently, the unil has been accorded formal stratigraphic rank as the "Two Rivers Member of the Kewaunee Formatioo" (Mickelson and others, 1984). The Kewaunee Formation com­prises all red clayey till units of eastem Wisconsin (Fig. 2); be­sides the Two Rivers Member, it ineludes three additional Lake Michigan Lobe deposits-the Ozaukee Member, lhe Haven Member, and the Valders Member (Mickelson and others, 1984).

For the Iype locality of the Two Rivers till, Evenson desig­nated a sand pit on Ihe east side oC Wisconsin Highway 42 at

LAKé

MICHIGAN

1. Map of part of east-central Wisconsin showing localities distribution of units. Modified from Mickelson and Evenson (1975,

Fig. 1); area of Yalders till (ooarse stippled pattem) and Yalders tilllimit frOID Acomb (1978, Fig. 6).

GREEN eA y Lose LAKE MICHIGAN loeE

WEST SIOE EAST SIOE

MlODLE INLET GlENMORE TWO RIVERS MEMBER MEMBER MEMSER

KEWAUNEE YALOE.RS MEMBER KIRBY LAKE CHllTON

FORMATION MEM6ER . ....eMBER HAVEN MEMBER

SllVER ClIFF BAANCH RlVER MEMBER MEMBER OZAUKEE MEMBER

Figure 2. Red clayey till units of eastem Wisconsin. Not shown is the new1y defined Florence Member, which occurs beneath the Silver Cliff Member on the west side ofthe Green Bay Lobe (Clayton, 1988). The Two Creeks bed, whicb occurs between members oC the Kewaunee Formation, is not recognized as a formal lithoStratigraphic unit of the formation (Mickelson and others, 1984).

the north edge of the city of Two Rivers (Evenson, 19733, p. 2289-2290, 2296; 1973b, p. 16-18, 22). The till was correlated with till of similar lithology tha! overlies the Two Creeks Forest Hed at the Two Creeks type section 18 km north oC Two Rivers (Fig. 3), and thus lhe Two Rivers till was considered to be póst-Twocreekao or Greatlakean (Evenson and others, 1976) in age. Correlation of the red till at Two Rivers with that al Two Creeks was subsequently supported by the investigalions of Mickelson and Evenson (1975) and Acomb (1978; Aeomb and others, 1982).

Al its type section lhe Two Rivers till sharply overlies lacus­trine sands (Figs. 3 arid 4), whieh Evenson (1973a, b) interpreted as deposits of the Gleñwood phase of glacial Lake Chicago. A water well drilled at the site showed the sand to be 9 m thiek and to overlie 25 m of another red·till unit that rests on bedrock, Hecause the Glenwood phase is clearly pre-Twocreekan in age, as demonstrated by Eschman and Farrand (1970) in Michigan .nd by ~chneider and Reshkin (1970) in Indiana, the lower red lill al Two Rivers must also be pre-Twocreekan. Evenson correlated this lower red till with the till below the forest bed at the Two Creeks type section and with the red Valders till of Thwaites (1943; Thwaites and Rertrand, 1957) at its type locality (Fig, 3).

More recently, however, Aeomb (1978; Acomb and others, 1982) identified two additional pre-Twocreekan Lake Michigan Lobe red-till units (Fig. 2): the Ozaukee and Haven Members of the Kewaunee Formation (Mickelson and others, 1984), both of whieh he believes are older Ihan the Valders till. The lower till al both the Two Rivers and Two Creeks type seetions is considered by Acomb to be part oC the Haven Member, and the Valders till is believed to be .bsent al both these localities. In any event, both the Ha ven and Valders tills are considered to be pre-Twocreekan oc late Woodfordian in age, and the Two Rivers till is correlated as post-Twocreekan or Greatlakean. Black (1974, 1978, 1980), on the other hand, argued that the red till at Valders is post­Twocreekan in age and correlated it with the upper red till al both Two Creeks and Two Rivers. Until Blaek's untime1y death in 1983, the controversy between Blaek and the Evenson­Mickelson group over the age of the type Yalders till had eon­tinued almost unabated for a full decade.

102

Greatlakean age 01 the type Two Rivers till S3

Valders Two Rivers Two Creeks Manitowoc R.

Type Locality Type Locality Type Locality K o m e $

I ... oi e e

'-l l .... .... I

o ~. Y."~ ~ " ,,0000" • • • • 'c'" .. " .. " c " " " "" w /.; ~ R d T' I l' ',,"" ~,J ,J Fa' e $ I . I~ .;.,' e ,,' " .J " • "~o 00"" " " .~ :', Gro y Ti II .- - .- . -,:.', '::-·1 r· l'o k e .:" B e d $' . ''-

Sed • • : : ~ ':' "! .' . ': 0: " ,": ~ ." -: R e d () o " -" ... :" .. " "O..l "00 0.J "" .. .,°. 0 lake ?~. ~ ","" "", T ¡ I I level

, .. ,oo··"Q"ooo"o".>oo" .. "J ... . ? . "!-.4.-_o" ~~.?.L

Figure 3. Diagrammatic cross section from Valders type locality to Two Rivers type locality to Two Creeks type locality. Not to seale. Slightly modified from Evenson (1973a, Fig. 6).

AGE OF THE TWO RIVERS TILL

Unlike the age orthe Valders till, the age ofthe Two Rivers lill has not been the subjeet of direet controversy. Consideration of its age, however, is obviously inseparable from the question of the age and correlation of the Valders tillo Neither the age of the Valders Member nor the age of the Two Rivers Member al their respective type localities has been demonstrated previously by radiometrically dated material.

Two Rivers site

In July of 1968, abou! three years before Evenson began his investigations in eastero Wisconsin, the site later designated by Evenson as the type locality ofhis Two Rivers till was visited by a geography class from the University of Wisconsin-Milwaukee, Part of a moderately large log completely enclosed in till (Fig. 5) was observed, photographed, and colleeted bymembers of the class at that time.

Knowledge ofthis wood sample remained Iimited, however. In 1982 I learoed about the log and obtained it from Paul Stoel­ting of Carthage College, who as a graduate studenl was involved in its colleetion 14 years earlier. Part of the log was submitted to the radiocarbon laboratory of the Illinois State Geological Survey and dated at 11,910 ± 120 yr B.P. (ISGS-1058; Liu and others, 1986, p. 131). The wood, therefore, is unquestionably Two Creeks wood, inasmuch as the accepted average age of the Two Creeks Forest Bed is 11,850 ± 100 radiocarbon years (Broecker and Farrand, 1963). Thus the Two Rivers till at its type locality is younger than the Two Creeks Forest Bed, from which the log must have been derived by Ihe ice. The date aIso confirrns that the correlation of the red till aboye the laeustrine sands at Two Rivers with the red till aboye the forest bed at Two Creeks is indeed corree!.

103

Because the size and eonfiguration of the Two Rivers pil have ehanged through the years, it is diffieult to determine the exaet location of the log within the outline of the present excava­tion. Stoelting and I are confident, however, that the wood was taken from the north wall of the pit, probably about 25 to 35 m east 'of the spot photographed and diagrammed by Evenson (1973a, Fig. 5, p. 2290; 1973b, Fig. 5, p. 17) to show the relation between red clayey Two Rivers till and deformed ice-shoved Glenwood laeustrine sediments.

Kewaunee site

Two radiocarbon ages have been deterrnined on wood samples from the type section of the Kewaunee Formation (Mickelson and oth~rs, 1984), located along the Lake Michigan

Figure 4. Photograpb sbowing Two Rivers till overlying lae",trine sand at the Two Rivers type locality, Two Rivers, Wisconsin. Pboto taken June, 1979.

54 A. F. Schneider

Figure 5. Photograph showing dated log in Two Rivers till at the Two Rivers type locality. Photo courtesy orPaul Stoelting; taken July, 1968.

shore at Ihe south edge of the city of Kewaunee, about 14 km (8.7 mi) north of the Two Creeks type section and 32 km (20 mi) north of the Two Rivers type section (Fig. 1).

Fine-grained reddish-brown lilI at the top of Ihe Kewaunee seclion 30 m' aboye lake level was correlaled with the reddish­brown lill Ihal overlies the Two Creeks Forest Bed at ils type locality by Acomb (1978) and Acomb and others (1982) and thus called Two Rivers tUl. The till is underlain by a blaek, snaU-rieh organie layer, mostly peat, that ranges from 5 to 13 cm thick (Fig. 6). Barry Miller of Kent State University has studied the snaíl fauna, and the beetle population has been analyzed by Clarke Garry and Donald Schwert. The fauna and paleoenviron­menl of the site are considered in a companion paper (Garry and others, this volume).

Wood from the top oC the arganic layer al the Kewaunee site thal 1 eollected in 1981 was dated by the l11inois State Geo­logical Survey lab al 11,700 ± 110 yr B.P. (ISGS-I061; Líu and others, 1986, p. 131). A second wood sample collected from the organie layer by Professors Garry and Baker in 1983 yielded a similar age oC 11,650 ± 170 yr B.P. (ISGS-1234; Garry and others, this volume). Both dates are considered to be late Two. ereekan dates. Thus the overlying red clayey till must be post­Twocreekan (Greatlakean) in age, as previously correlated by Acomb.

The radiocarbon <!Jites from Ihe Kewaunee site call attention lo Ihe several dates on organic-rich lake sedimenls from cores taken in 1970 from nearby Seidel Lake by H. E. Wright, Jr. Seidel Lake is a tiny lake thal occupies an enclosed depression on the Two Rivers till surfaee less than 2 km wesl of the Kewaunee site. The younger Seidel Lake dates (Bender and others, 1975, p. 131) are generally compatible with the new dates from the Kewaunee bluff site, with the possible exeeption of the

104

11,620 ± 110-yr B.P. date (WIS-641), which appears to'be some­what too old (although nol inconsisten!) for a post-Two Rivers date by comparison with the pre-Two Rivers (1:wocreekan) dates from the Kewaunee site. A previously deterrnined date of 12,360 ± 125 yr B.P. (WIS-462; Bender and olhers, 1971, p. 480) rrom Seidel Lake was acknow1edged to be inconsisten! with the identificalion of the enclosing till.

CONCLUSION

Radiocarbon dates from Ihe Two ~ivers and Kewaunee sites firmly establish the age oC the Two Rivers till as post­Twocreekan or Greatlakean. Thus, it is the age of Ihe Valders lill Ihat musl now be demonstrated by radiometric dates, in order lo determine whether it correlates with the Two Rivers till, as Blaek contended, or is indeed pre-Twocreekan (late Woodfordian) as held by the Evenson-Mickelson group. The evidenee at this lime strongly Cavors Ihe latter inlerpretalion. Unless and unli! sueh time as datable organie material is found in Ihe Valders till al ils type locality, however, sorne question as to the age oC this red-till unit will remain.

, Figure 6. Pholograph ofTwocreekan organic layer beneath Two Rivers till at Kewaunee, Wisconsin. Wood twig in upper lertjust below contac! was dated al 11,700 ± 110 yr R.P. (ISGS-1061). Light-colored spots in organic layer are mollusc shells. Pholo taken July, 1981.

ACKNOWLEDGMENTS

1 thank Paul Stoelting, now al The University oC Wisconsin­LaCrosse, Cor supplying the log from the Two Rivers site and also for photographs taken when the log was collected. The Illinois State Geological Survey deterrnined the radiocarbon age oC the log and also dated the wood samples from the Kewaunee sile. The manuseript was reviewed by E. B. Evenson, R. C. Flemal, and W. N. Melhom.

Greal/akean age ollhe type Two Rivers liIl 55

REFERENCES ClTED

Acomb, L. J., 1978, Stratigraphic relations and extent ofWisconsin's Lake Mich· igan Llbe red t.ms[M.s. thes~t. Madison, University ofWisoonsin-Madison. 68 p.

Acomb, L. J., Mickelson, D. M.o and Evenson, E. B., 1982, Ti1Istratigraphy and late glacial eveRts in tbe Lake Michigan Lobe oC eastem Wisconsin: Geologí­cal Society oC Amena Bulletin, v. 93, p. 289-296.

Alden, W. C" 1906, Description oC tbe Milwaukee Quadrangle, WLsconsin: U.S. Geological Survey Geological Atlas, Folio 140, 12 p.

- I 1918, The Qualemary geology oCsoutheastem Wisconsin: U.S. Geological Survey Professional Paper 106, 356 p.

Bender, M. M" Bryson, R. A., and Baerreis, D. A., 1971, University ofWi.sconsin radiocarbon dates IX: Radiocarbon, v. 13, p. 475-486.

-- • 1975, University ofWisconsin radiocarbon dates XII: Radiocarbon, v. 17, p.121-134.

Black, R. F., 1974, Late Pleistocene shoretines and stratigraphic relations in the Lake Michigan basin; Discussion: Oeological Soclety oC America Bulletin, v. 85, p. 659-660.

-- , 1978, Comment on 'Oreatlakean Substage; A replacement Cor Valderan Substage in the Lake Michigan basin' by Evenson, E. 8., and olhers: Quater­nary Research, v. 9, p. 119-123.

-- , 1980, Valders-Two Creeks, Wisconsin, revisited; The Valders liII is masl likely ~t-Twocreekan~ Geological Society oC America Bulletin, Part 1, v. 91, p. 713-723.

Broecker, W. S., and Farrand, W. R., 1963, Radiocarbon ageoClheTwo Creeks Forest Sed, Wisconsin: Geological Society oC America Bullelin, v. 74, p.795-802.

Chamberlin, T. C., 1877, Geology oC easlem Wisconsin, ln Geology oC Wiscon­sin, Survey oC 1873-1871: Wisconsin Geological Survey, v. 2, p. 91-405.

Oayton, L., 1988, Florence Member oClhe Kewaunee Formation, in Anig, J. W., Clayton; L., and Mickelson, D. M., 005." Pleistocene stratigraphic units 'oC Wisconsin, 1984-1987: Wisconsin Geological and Natural History Survey InConnation Circular 62, p. 57-59.

Eschman, D. F., and Farrand, W. R., 1970, Glacial history oC the glacial Grand Valley, In Guide Book Cor field trips; Nortb-Central Section, Geological

Society oC America meeting, Eas! lansing, Michigan: Michigan Basin Oeo­logical Sociely, p. 131-157.

Evenson, E. 8., 1973a, late Pleistocene sborelines and stratigrapbic relations in tbe Lake Michigan basin: Geological Society oC America BuUelin, v. 84, p.2281-2298.

- , 1973b, A reevaluation oCtbe "Valders" limitin Ibe lake Michigan basin, In Evenson, E. 8., Eschman, D. F., and Farrand, W. R, The "Valderan" probtem, Lake Michigan basin, 22nd Annual Midwest Friends oC the Pleis­locene Field ConCerenre Guidebook: Ann Arbor, Micbigan, Midwest Friends oC the Pleistocene, 29 p.

Evenson, E. B., Farrand, W. R., Mickelson, D. M., q.chman, D. F., and Maher, L. J., 1976, Greatlakeal.1 Subslage; A replacement Cor Valderan Substage in tbe Lake Micbigan basin: Quatemary Research, v. 6, p. 411-424.

Liu, C.-L., Riley, K. M., and Coleman, D. D., 1986, Dlinois State Oeological Survey radiocarbon dates IX: Radiocarbon, v. 28, p. 110--133.

Mickelson, D. M., and Evenson, E. B., 1975, Pre-Twocreekan age oC the type Valders till, Wisconsin: Geotogy, v. 3, p. 587-590.

Mickel.son, D. M., Clayton, L., Baker, R. W., Mode, W. N., and Schneider, A. F., 1984, Pleistocene stratigrapbic unils oC Wisconsin: Wisconsin Geological and Natural History Survey Mi.scellaneous Paper 84-1, 97 p.

Schneider, A. F., 1984, Radiocarbon confirmation oC Ibe Greatlakean age oC the Iype Two Rivers till or eastem Wisconsin: Geological Society oC America Abslrac~ wilh Programs, v. 16, p. 193.

Schneider, A. F., and Resbkin, M., 1970, Age and correlation oC the Glenwood stage oC glacial Lake Chicago: Geological Society oC America Abslracts with Programs, v. 2, p. 404.

Thwaites, F. T., 1943, Pleistocene oC part oC northeastem Wisconsin: Oeological Society oC America Bulletin, v. 54, p. 87-144.

Thwaites, F. T., and Bertrand, K., 1957, Pleistocene geology oC the Door Penin­sula, Wiscons.in: Geological Society oC America Bullelin, v. 68, p. 831-879.

• MANUSCRIPT ACCEPTED BY TItE SocIETY QcrOBER 9, 1989

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Printtd in U.S.A.

106

Geological Society oC America Special Pape, 251

1990

Environmental analysis of a Twocreekan-aged beetle (Coleoptera) assemblage from Kewaunee, Wisconsin

C1arke E. Garry Departmenl 01 Bi%gy, University 01 Wisconsin-River Fa/Is, River Fal/s, Wisconsin 54022 Robert W. Daker Departmenl al Planl and Earth Science, University al Wisconsin-River Fa/Is, River Fa//s, Wisconsin 54,022 Donald P. Schwert Departmenl al Ge%gy, North Dakola Slale University, Fargo, North Dakola 58105 Allan F. Scboeider DepartmenloIGe%gy, University al Wisconsin-ParkSide, Kenosha, Wisconsin 53141

ABSTRACf

A Twocreekan organic horlzon, which ls underlaln by till of Ihe Haven Member and overlaln by liU of Ihe Two Rivers Member of Ihe Kewaunee Formalion, was investlgaled near Kewaunee, Wlsconsin. Wood from Ihls horlzon was daled al 11,700 ± 110 D.P. (lSGS-I061) and 11,650 ± 170 D.P. (ISGS-I234). The ioseel fauna from Ihe Kewaunee sile has many elemenls in common wlth Ihe insecls from Ihe type sectlon of Ihe Two Creeks Forest Bcd, 14 km lo the soulh. These inelude Ihe northwestem carabid Asaphidion yukonense, northem carabids Carabus laedalus and Bembidion grapi~ and Ihe northem staphylhúd Acidola quadrata. In eonlrast, Ihe Kewaunee site fauna appears to hine inhabited a somewhal colder environmenl, as suggesled by Ihe oceur­renee of Ihe carabids Cymindis unicolor and Pterostichus (Cryobius) spp. We inlerpret Ibe Kewaunee speclmens of aquatle, waler-marginal, and upland species lo represenl an aIIochthonous rather Ihan an autochthonous assemblage.

INTRODUCfION

Virtuallyall knowledge regarding the Twocreekan paleoen­vironment of the western Lake Michigan basin has been derived from extensive studies of the type locaIity of !he Two Creeks Forest Bcd (Fig. 1), located approximately at the border of Ke­waunee and Manitowoc Counties, Wisconsin, between Seco 35,T.22N.,R.24E. and Sec.2,T.2IN.,R.24E. (44°19'30"N, 87°32'36"W). The average radiocarbon date on wood from the fores! bed is 11,850 D.P. (Broecker and Farrand, 1963; Morgan and Morgan, 1979); these dates have becn used to establish the chronology of Ihe northward recession of ice in the Lake Michi­gan basin associated with the Twocreekan Substage (Evenson and others, 1976).

The type locality of the Two Creeks Fores! Bed has gener­ated considerable interest in the late-glacial history of the Lake

Michigan basin. Goldthwait (1907) recognized that red tills He stratigraphically aboye and below the forest bed and interpreted !he sequence as recording more than one glacial advance. Later, the upper red till was corcelated with the red surface till at Valders, Wisconsin (Bretz, 1951; Thwaites and Bertrand, 1957; Frey and others, 1968; B1ack, 1970, 1980), suggesting a major post-Twocreekan readvance. Evenson (19733, b) was the first to suggest that this corcelation was erconeous. He argued that the surface tm at Valders corcelated with the lower red till at Two Creeks and the upper red till represented a significantiy less exten­sive readvance than previously believed. This view has becn sup­ported by subsequent studies in the central Great Lakes region (Evenson and Mickelson, 1974; Mickelson and Evenson, 1975; Evenson and others, 1976; Evenson and Dreimanis, 1976; Far-

Garry, C. B" Baker, R. W., Scbwert. D. P" and Scbneider, A. F., 1990, Environmental analysis or a Twocreekan-aged beetle (Coleoptera) a.ssemblage rrom Kewaunee, Wisconsin, in Schneider, A. F., and Fraser, G. S., eds., late Quatemary history or tbe Lake Michigan basin: Boulder, Colorado, Geological Society oC America Special Paper 251.

107

58 C. E. Garry and Olhers

Manitowoc

I 10ml I 16km

Figure l. Map showing the location of the Kewaunee site in relation to . the type section of the Two Creeks Forest Bed.

rand, 1976; Acomb and others, 1982; Miekelson and olhers, 1983).

In Ihis ehapler, we describe aD organie horizon of Two­ereekan age al Kewaunee, Wisconsio, and compare ils inseet remains lo Ihose previously described from Ihe Two Creeks Iype seelion 14 km lo Ihe soulh (Fig. 1).

PREVlOUS STUDIES

Sludies of Ihe pollen and planl remains of Ihe Two Creeks Foresl Bed were initiated by Goldlhwail (1907, p. 61), who described !he preseoce of a "conspicuous bed of peal, stieks, logs, and large Iree lrunks, whieh unmistakably represenls a glacialed forest." Cheoey (1930,1931), Wilson (1932,1936), and Culber­son (1955) described 23 species of mosses allogelher, mosl of whieh were associaled with floras of more northem affinities. In addition lo mosses, Wilson (1932, 1936) idenlified macrofossils of bolh blaek spruce (Picea mariana) and white spruce (P. glauca).

The firsl detailed palynologie analyses of Ihe Two Creeks Foresl Bed localily were condueled by Wesl (1961). He found Ihal spruce made up 80 lo 90 percenl of Ihe lotal pollen conlenl, wilh Ihe pollen of while spruce far exceeding Ihal ofblaek spruce. He coneluded Ihal Ihe flora was elearly boreal in eharaeler.

Sludies of Ihe invertebrale remains associaled with Ihe planls al Ihe Iype localily have cenlered primarily 00 molluscs and iosecls. Eighl species of molluscs described by Wilson (1932) from Ihe forest bed were primarily oorthern forms. Morgan and Morgan (1979) ideolified a fauna of 49 taxa (21 species) of beetles (Coleoplera). The fauoa ineluded six species of bark bee­tles (Scolytidae), nearly al1 of whieh are associaled wilb spruce. They inlerpreled Ihis "reslrieled" assemblage as haviog accumu­laled in situ aod as represeoling a dry boreal foresl eoviroomenl wilh sorne opeoings and a sparsely vegetaled grouod suñace.

LOCATION, STRATIGRAPHY, AND AGE OF THE KEWAUNEE SECTION

Our study seelion (Fig. 1) is localed along Ihe shoreline of Lake Miehigan 00 a 30-m bluff al Ihe soulh edge of Kewauoee, Wisconsin (NE\4SEIJ<8E\4,Sec.19,T.23N.,R.25E., Kewauoee 7.5-min Quadrangle; 44"26'49"N., 87°30'8"W.). The stratigraphy of!he sile is described in Table I aod iIIuslrated in Figure 2.

Two radiocarbon dales were obtained on wood from Ihe Kewauoee sile: 11,700 ± 110 B.P. (ISGS-I061) and 11,650 ± 170 B.P. (ISGS-1234). These dales compare favorably wilh Ihose from Ihe Two Creeks Foresl Bed reported by Broecker and Far­rand (1963), wilh ao average radiocarbon dale of 11,850 B.P., and by Morgán and Morgao (1979), with dales of 11,810 ± lOO B.P. (GSC-2166) and 11,860 ± 110 B.P. (WAT-57) .

MEmODS

Malrix partiele-size analyses for all uoils were made using Ihe bydromeler melhod (Blaek, 1965) wilh measuremeols given io U.S.D.A. partiele size elasses and q, unils [sand = 2.0 lo 0.05 mm (-1.0 lo 4.25 q,), silt = 0.05 lo 0.002, mm (4.25 lo 9.0 q,), and elay <0.002 mm «9.0 q,)]. Clay-mineral delerminalions were made by H. D. Glass of Ihe lIlinois Stale Geological Survey. . A lotal of 64 kg of sedimenl was col!eeled in bulk for inseet analyses from Ihe orgaoie horizon. Chilinous remains were ex­lraeled from Ihe organics followiog a lechnique described by Schwert and Morgan (1980). Bulk samples were lirsl washed Ihrough a 52-mesh (300-l'm) sieve lo remove Ihe silt and elay fraelioos. The residue was subjecled lo a kerosene flotalioo lo concenlrale Ihe insecl remains. The parts were mouoled wilh gum tragacanlb onlo mieropaleonlological slides. As al! of Ihe species represenled appear lo be extanl, identilicalions were made using the modem reference colleclions of Ihe Geology Depart­ment and Ihe Stale Insect Col!eclion, bolh al North Dakota Stale Universily. The fossils have been deposiled in the colleclioo oí Ihe Departmen! of Biology, Universily of Wisconsin-River Falls.

DESCRIPTION OF mE FAUNA

Among Ihe ehitioous remains exlraeled are oslracods, ela­doceran ephippia, spiders, and oribalid miles. Additionally, al leasl six orders of inseels, ineluding Hemiplera (Pentalomidae,

108

AlUllyses 01 a Twocreekan-aged beetle assemb/age 59

Saldidae), Homoptera (Cicadellidae), Coleoptera (17 families), Triehoptera, Diptera (Chironomidae), and Hymenoptera (For­micidae) were present. The insects are dominated by Coleoptera; over 600 beetle individuals representing 59 taxa have been identi­fied (Table 2)_ AIso present in the horizon were six species of aquatie molluscs, including Stagnico/a elodes, Fossaria obrussa, Gyraulus ef_ parvus, G. er. deflectus, G. ef. altissimus, and Pis­Idium casertanum, and one terrestrial taxon, Vertigo spp. (B. B. Miller, written communication, 1983).

STRATIGRAPHIC UNIT

DEPTH PARTICLE SIZE %

o 25 50 75 100

ela)' 5111 Sond

2 Both the sediments and inseet fauna evidently accumulated

in a shallow body of water. That this water was in part open is apparent rrom the presence of sueh aquatic beetles as Dytiseus, Colymbetes, agabine dytiscids, and at least one gyrinid (Fig. 3f). The local presence of marshy rones of sedges or grasses is indi­cated by the chrysomelids Donada and P/ateumaris (Fig. 3g), as well as by omaliine staphylinids and two species of the carabid Elaphrus. These zones were in part bordered by open, probably sandy patches that supported heterocerids, scarabs (Aegialia), carabids (Bembidion sordidum, B. grapii (grapei), and Dyschi­rius spp.), staphylinids (Stenus and Bledius), and byrrhids. Indi­cators of drier upland habitats are also present in the assemblage. These inelude the carabids Carabus taedatus, Pterostichus (Cry­obius) spp., Pterostichus adstrictus, Cymindis unicolor, Notiophi­fus sp., and Miscodera aretica.

TWO RIVERS MEMBER 111111

ORGANIC SEDIMENT __ _

BEACH GRAVEL

HAVEN MEMBER

11/111

3

4

5

6

7

Figure 2. Stratigraphy ofthe Kewaunee Formation at the Kewaunee site.

TABLE 1. SECTlON DESCRIPTlON OF THE KEWAUNEE FORMATlON AT THE KEWAUNEE SITE'

Unit Deplh (m)

Two Rlvers Member (till) 0.00-3.66

Organle Sediment 3.66-4.33

Beacll Gravel 4.33-5.70

Haven Member (till) 5.7+

• Deseription

Cslcareous, Ioam-texrurad till averaglng 43.7 pereent sand, 31.3 pereent silt, and 25 pereent e/ay. Modem solum lo deplh 010.4 m wllh leaehing to deplh 01 0.55 m. Cólor vartes Irom light reddish brown (5YR 6/4) In wealhered zona to reddish brown (5YR 4/4) in unwealhered state to dark brown (7.5YR 4/4) near base. Pebbly, cantalnlng numerous dolomite elasts as well as Igneous e/asts 01 rhyolite porphyry. Matrix e/ay-mineral content averages 60.5 pereent iIIite. 16.5 pereent kaalinite plus chlorite, and 23 percent expandables. lower 0.3 m contains numerous iron-oxide stre.ks, discontinuous /enses 01 dark graylsh brown (10YR 4/2) organie-rleh Ioam, and lewer pebb/e-sizad elasts. Abrupt lower boundary.

S~ong/y calcareous very dark gray (10YR 311) silt 108m averaging 30 pereent sand, 61 pereent sllt, and 9 percant elay. Conta/ns abundant wood Iragments, mol/uses, and insects. Interpreted to be shallow-watar lacustrine In origino

S~ong/y calcaraous, very gravelly sandy 108m averaging 58.5 pereent sand, 31.8 percant silt, and 9.7 pareent e/ay. Colorvarles Irom dark yellowish brown (10YR 4/4) to dark brown (7.5YR 4/4). Contalns many angular to suban guiar pebblas and Is inlerpretad to be be.eh or shallow lacustrine In origln. Lower contact abrupt.

S~ongly calcaraous Ioam-textured till avaraging 39.0 pereent sand, 31.4 pereent silt, and 29.4 percant e/ay. Matrix color varles Irom dark yaUowish brown (10YR 4/4) near top to pinkish gray (5YR 7/2) wilh depth. Clay-mineral content averages 54.0 pereent iIIite, 20 pereent kaolinite plus cIllorlte, and 26 pereent expendables. Total thickness undeterminad due to poor exposura.

'Elevatlon 01 upper surfaca approximate/y 204 m.

109

110

Ana(yses of a Twocreekan-aged beetle assemb/age

10.1

a b

d

1 f 9

Figure 3. Selected fossils from the Kewaunee site. Seale ba, equals I mm, except whe,e indicated as a f,action (0.1) of I mm. a, pronotum of Acldota quadrata; b, pronotum of Cymindis unicolor; e, left elytron of Asaphldion yukonense; d, right elytron of Bembldion moru/um; e, left elyt,on of Cymindis unicolor; f, left elytron of Gyrinus sp.; g, left elytron of Plafeumaris sp.

111

61

62 C. E. Garry and Olhers

Among the laxa are beetIes that are typically northem. These inelude Acidola quadrala, Pterosnchus punclalissimus, and Miscodera arclica. Acidola quadrala (Fig. 3a) is a staphylinid beetle that today ranges from tbe southem Iimit of tbe boreal fores! into arctic and alpine environments (Fig. 4a; Campbell, 1982); it iohabits leaf Iitter, moss, aod clumps of sedges (Carex; Campbell, 1982). Pterosnchus punctalissimus is a large ground beetle Ibat presently raoges throughout tbe boreal forest (inelud­ing oorthem Wiscoosin) up to treeline, but it has yet to be re­corded from Alaska (Fig. 4b; Lindroth, 1966); it is the dominant forest-floor carabid of the northem boreal forest. Miscodera arc­l/ca is distributed across northern North America from Alaska to Labrador, south to Maine, New Hampshire, New York, Wiscon­sin, Montana, an\! Washington (Lindroth, 1961). We bave col­leeted M arcnca on dry, sandy areas in both open and elosed environments.

Additionally, several beetles are of particular interest be­cause of their ecology or distribution:

Asaph/d/on yukonense (Fig. 3c). This carabid beetle is pres­ently restricted lo northwestern North America (Fig. 4f), ranging from easlem Alaska soulhward into the mountains of Alberta. The beetle inhabits open palches of clay and sill substrales with sparse vegetation, often in riparian habitats (Lindroth, 1963; Morgan and Morgan, 1979). A. yukonense has previously been' recorded as fossils from Ihe Two Creeks Forest Bed (Morgan and Morgan, 1979).

Cymindis un/color (Fig. 3b, e). Lindroth (1969) described tbis beetle as an arctic-alpine species occurring in tundra and tundra-Corest transition zones from Alaska to Labrador (Fig. 4d). !solated populations occur in tundra-like microenvironments on tbe northem shore of Lake Superior and in alpine zones in the Rockies and New England.

Carphoborus andersoni This scolytid beetle inhabits white spruce (Picea glauca), burrowing in the inner bark and sapwood of the lower shaded and broken branches (Bright, 1976; Ash­worth, 1977) and also inhabits shaded-<lut and dying spruce (Morgan and Morgan, 1980). Its modem dismbution is distinctly northwestem (Bright, 1976; Wood, 1982; Fig. 4e). C. andersonl was the only bark beetle found in the Kewaunee assemblage; this is surprising because spruce needles were found in tbe associated planl debris, although not in great numbers.

Bemb/dion morulum (Fig. 3d). The modem distribution of this carabid beetle is described by Lindroth (1963) as being dis­tinctly northem, almost transamerican, and not found in the United States. Records occur from Newfoundland, northem Mani!oba, A1berta, Northwest Territories, British Columbia, and tbe Yukon, as well as Alaska (Lindroth, 1963; Fig. 4c). This carabid usually inhabits pond-marginal vegetalion.

Pterosl/chus (Cryobius) spp. The Cryobius subgenus of Pteroslichus is, according to Lindrolh (1966), " ... the mos! strik­ing elemenl of tundra." We appear to have two species. One pronotum is similar to P. (Cryobius) riparius, a species now confined to westem North America, raoging from Alaska south­ward to Oregon and probably oorthem Califomia (Ball, 1966).

Three prQnota are close to P. (Cryobius) brevicomis, a species that has a range similar to that of Cym/ndis unicolor, including an isolated occurrence on the oorth shore of Lake Superior.

DISCUSSION

Because the Kewauoee and Two Creeks sites are virtually the same age and are located witbio 14 km of each other (Fig. ¡), ooe might expect tbem to have experienced a similar sequence of events during late Wisconsinan time. Al both sites the organic sediments are underlain and overlain by tills of the Haven Member and tbe Two Rivers Member of the Kewaunee Forma­tion, respectively (Mickelson and others, 1984; Fig. 2). Sedimen­tologically, bowever, they are somewhat different. At the Two Creeks site the organicsediments are thin (0.03 to 0.3 m) and are ineluded within a 5-m sequence of lacustrioe sediments (Mickel­son and others, 1984), while at Kewaunee they are tbicker (0.35 to 0.70 m) and are located near Ihe top of a 2-m sequence of shallow lacustrine sedimenl (Fig. 2).

The Kewaunee insect fauna has many elements in common with that of the Two Creeks Forest Bed (Table 2; Morgan and Morgan, 1979), ineluding the northwestem carabid Asaphidion yukonense .. northem carabids Carabus laedalus and Bembid/on grapii, and the northem staphylinid" Acidola quadrala. Specific habitat indicators common to both sites inelude the water­marginal limnebiid Ochlheb/us sp., staphylinids Bledius sp., Slen~ sp., and Olophrum sp., scarab Aegialia sp., and byrrhid Cylilus sp. However, in contrast to the fauna at Two Creeks is the presence of opeo-water beetle species at Kewaunee. Close ana­logues to both the Kewaunee and the Two Creeks faunas occur today in the boreal forest of North America. This generalized interpretation is compatible with conelusioos published on the Two Creeks Forest Bed from vegetational sludies of Cheney (1930,1931), Wilson (1932,1936), Culberson (1955), .nd West (1961).

The fauoa ofthe Two Creeks site was interpreted as repre­senting the southem half of the boreal forest (Morgan and Mor­gan, 1979). That the Kewaunee fauna appears to have inhabited a somewhat colder environment and is more representative of the nortbern boreal forest zone is indicated by the occurrences of Bembidion morulum, Cym/ndis unicolor, and beetles of the arctic/ subarctic subgenus Cryobius. The latter two taxa indicate an oyen forest environment, perhaps even spruce parkland uplands sur­rounding the depositional basin.

It appears tha! tbe fragmeots of the upland speeies are more abraded than those of the aquatic and water-marginal beetles. This is an important consideration as it may il1dicate tha! frag­meots of the upland beetles were transported sorne distance to the site. Therefore, the assemblage may be more regionally represen­tative than that at Two Creeks.

In addition to Two Creeks, the Kewaunee fauna can be compared to other midcontinental ioseet assemblages of similar age along the southem margin of the Laurentide ice sheet. Two faunas of special interest are those at Norwood, Minnesola (upper

112

l.

Anolyses 01 a Twocreekan-aged beelle assemb/age

Pleroslichus punclatlsslmus

d

f

Figure 4. Maps sbowing modem distributions oC selected beetles (black dots) and location oC tbe Kewaunee site (open cirele).

113

63

64 C. E. Garry and O/hers

section; Asbwortb and others, 1981), and Eighteen Mile River, Huron County, Ontario (Ashwortb, 1977). The ioseet assem­blage ofNorwood (uPPer section) is most like that of Kewaunee. Beetles in common with Kewaunee between the two.assemblages inelude the carabids Carabus /aedatus, Bembidion sordidum, B. morulum, Pte,osiichus punc/atissimus, Cymindis unicolor, and the scolytid Carphoborus andersonL Upper Norwood was inter­preted to be a stable coniferous forest within a relatively uniform c1imate. Temperatures were infereed to be similar to !hose now associated with the boreal forest south ofthe tundra-forest transi­tion zone (Ashworth and others, 1981). Faunal elements in common ~tween Kewaunee and the Eighteen Mile River as~ semblages ¡nelude the beetle species Miscodera are/ka, Asaphid­ion yukonense, Bembidion sordidum, and Carphoborus ander­soni Eighteen Mile River inseet fossils were interpreted to represent a cold valley microenvironment with conditions similar to ¡hose of the tundra-forest transition zone of northem Canada (Ashworth, 1977).

REFERENCES CITED

Acomb, L. J., Mickelson, D. M" and Evenson, E. 8., 1982, TiII stratigraphy and late glacial events in the lake Michigan 10be oC easlem Wísconsin: Geologi­cal Society of America BuUetin, v. 93, p. 289-2%.

Ashwortb, A. C" 1977, A late Wisconsinan coleopterous assemblage rrom solltb· ero Ontarío aM ilS environmental significance: Canadian Joumal oC Eanb

. Sciences, v. 14, p. 1625-1634. Ashworth, A. C., Schwert, D. P., Watts, W. A., and Wrigh~ H. E., Jr., 1981,

Plant and insect füssils at Norwocxl in soutb-central Minnesota; A record oC late-glacial successioo: Quatemary Research, v. 16, p. 66-79.

Dall, G. B" 1966, A revisíon oC tbe North American species of tbe subgenus Cryohius Chaudoir (Pterostichus, Carabidae, Coleoplera): Opuscula Ento­mologica Supplementum, v. 28, p. 83-88.

Blaek, C. A., ed., 1965, Metbods oC soil analysis; Part 1, Pbysical and mineralogi. cal properties: Madison, Wisconsin, Amefican Society of Agronomy, Inc., p.545-566.

Black, R. F., 1970, Glacial geotogy ol Two Creeks Forest Sed, Valderan type locality, and nortbem Kettle Moraine State Porest: Wi.sconsin Geological and Natural History Survey lnlormation Circular 13, 40 p.

- , 1980, Valders-Two Creeks, Wisconsin, revisited; Tbe ValdersTiU is most likely post-Twocreekan: Geological Society of America Bulletin, Part 1, v. 9t, p. 713-723.

Bretz, J H., 1951, The stages oC lake Chicago; Tbeir causes and correlations: American Joumal ofScience, v. 249, p. 401-429.

Brigh~ D. E., Jr., 1976, The bark beeUes of Canada and Alaska (Co1eoptera: ScoIytidae); Tbe in.seclS and arachnids of Canada, Part 2: Canada Depart-ment of Agriculture Publication 1576,241 p. .

Broecker, W. S. and Farrand, W. R., 1963, Radiocarbon age of Ihe Two Creeks Forest Bed, Wisconsin: Geological Society cñ America Bulletin, v. 74, p.795-802.

Campbell, J. M., 1982, A revision oflbe Nortb American Omalünae (Coleoptera: Stapbylinidae); 3, The genus Acidota Stepbens: Canadian Entomologist, v. 114, p. 1003-1029.

Cheney, L S., 1930, Wisconsin f""il mDSSeS: Bryologis~ v. 33, p. 66-68. - , 1931, More fossil mosses from Wisconsin: Bryologist, v. 34, p. 93-94. Culberson, W. L, 1955, Th.e fossil mosses of the Two Creeks Porest Sed of

Wisconsin: The American Midland NaturaUst, v. 54, p. 452-459. Evenson, E. B., 1973a, Late Pleistocene shoretine:s and stratigraphic relations in

the Lake Micbigan basin: Geological Saciety of America Bullelin, v. 84, p.2281-2298.

ACKNOWLEDGMENTS

The autbors are indebted to A. C. Asbworth, North Dakota Sta1e University, and S. A. Elias, University of Colorado, Cm reviewing the manuscript. We appreciate the assistance ofE. U. Balsbaugb, North Dakota State University, and R. Freitag, Lake· bead University, in beetle identification. We also thank B. B. Miller, Kent State University, foe mollusc identification and R. G. Baker, University of Iowa, foe identification of the plant macr(}o fossils. Radiocarbon analyses and elay mineralogy determinations were provided with the help of L. R. Foll¡ner and H. D. Glass, respectively, of the lllinois State Geological Survey. Lab assist· ance was provided by B. Lagos, S. Fritsche, D. Johnson, S. Scheder, and D. Garey. This study was supported by University of Wisconsin-River Falls Grants 1015-2-83 and 1065-2-84 and the Department of Biology. •

- , 1973b, A reevalualion oftbe "Valders"limit in tbe lake Michigan basin, In Evenson, E. B., Eschman, D. F., and Farrand, W. R" eds., The "Valders" problem, Lake Michigan basin, 22nd Annual Midwest Friends of the Pleis­tocene Field ConCerence Guidebook: Midwest Friends of the Pleistocene, p. 1-29 .

Evenson, E. B., and Dreimanis, A., J 976, Late glacial (14,000-10,000 years B.P.) bistory of tbe Great Lakes region and possibte correlations, in Easterbrook., D. H., and Sibrava, V., eds., Quatemary glaciations in tbe Northem Hemi­spbere: Prague, IUGS-UNESCO Intemational Geological Corcelation PrOc grarnme, p. 217-239.

Evenson, E. B. and Mickelson, D. M., 1974, A reevaluation oC the Jabation and red titl stratigraphy and nomenclalure in part of eastem Wi.sconsin, In Knox. J. C., and Mickelson, D. M" eds., Late Quatemary environments oC Wiscon­sin: Wisconsin Geological and Natural History Survey, p. 102-117.

Evenson, E. B., Farrand, W. R., Eschman, D. F., Mickelson, D. M., and Maber, L J., 1976, Greallakean Substage; A replacement for Valderan Subslage in tbe Lake Michigan basin: Quatemary Researcb, v. 6, p. 411-424.

Farrand, W. R., 1976, Was tbere really a Valders?: Michigan Academician, v. 8, p.477-486.

Frey, J. e., Willman, H. B., Rubin, M" and Black, R. F., 1968, Definition of Wisconsin Stage: U.S. Geological Survey Bulletin 1274-E, 22 p.

Goldtbwait, J. W., 1907, The abandoned shore-Iines of eastem Wisconsin: Wisa consin Geolagical and Natural History Survey Bulletin 17, 134 p.

Lindroth, C. H., 1961, The ground·beetles (Carabidae, excl. Cicindetidae) of Canada and Alaska, 2: Opuscula Entomologica Supplementum, v. 20, p.I-200.

- , 1963, The ground-beetles (Carabidae, excl. Cicindelidae) oC Canada and Alaska, 3: Opuscula Entomologica Supplementum, v. 24, p. 201-408.

~ , 1966, The gróund-beetles (Carbidae, excl. Cicindelidae) of Canada and Alaska, 4: Opuscula Entomologica Supplementum, v. 29, p. 409-648.

- , 1969, The ground-beetles (Carabidae, excl. Cicindelidae) ofCanada and Alaska, 6: Opuscula Entomologica Supplementum, v. 34, p. 945-1192.

Mickelson, D. M., and Evenson, E. B., 1975, PremTwocreekan age oC tbe type Valders till, Wisconsin: Geology, v. 3, p. 587-590.

Mickelson, D. M., Clayton, L., Fullerton, D. S., and Boros, H. W., Jr., 1983, The Jate Wisconsin glacial record of Ihe Laurenlide ice sheet in the United States, in Wrigbt, H. E., Jr., oo., Late Quatemary environments oftbe United States; volume 1, The late Pleislocene: Minneapolis. Uníversity oC Minnesola Press, p.3-37.

114

Analyses 01 a Twocreekan-aged beetle assemb/age 65

Mickelson, D. M" Clayton, L., Baker, R. W., Mode, W. N., and Schneider, A. F.o 1984, Pleistocene stratigrapbic units oC Wisconsin: Wisconsin Geotogica1 and Natural History Survey Miscellaneous Papee 84-1, 91 p.

Morgan, A. V., and Morgan, A., 1979, Tbe fossit Coleoptera oC tbe Two Creeks Foces! Bed, Wisconsin: Quatemary Resea.rcb, v. 12, p. 226-240.

- ) 1980, Faunal assembtages and distnoutional sbifts oC Coteoptera during tbe lale PleLstocene in Canada and (he northem United States: Canadian Entomologis4 v. 112, p. 1105-1128.

Scbwert, D. P., and Morgan, A. V., 1980, Paleoenvironmental implications of a late glacial insect assemblage (rom northwestem New York: Qualemary Research, v. 13, p. 93-110.

Thwaites, F. T., and Bertrand, K.o 1957, Pleistocene geology oC Ihe Door Penin~ sula, Wisconsin: Geotogica1 Society oC America BuUetin, v. 68, p. 831-839.

115

West, R. G" 1961, Late- and postglacial vegetational bistory in Wisconsin, par­ticularly cbanges associated witb tbe Vatders readvance: American Joumal orsaeoce, v. 259, p. 766-7n

Wilson, L. R., 1932, The Two Creeks Forest Bed, Manitowoc County, Wiscon­sin: Transactions of the Wiscons1n Academy of Sciences, Arts and Letters, v. 27, p. 31-46.

-- ,1936, Furtber studies oribe Two Creeks Forest Bed, Manitowoc County, Wisconsin: Torcey Botanical Club Bulletin, v. 63, p. 317-325.

Wood, S. L, 1982, The bark and ambrosia beetles oC Nortb and Central America (Coleoptera: Scolytidae); A taxonomic monograpb: Great Basin Naturalist Memoirs 6, p. 380-382.

MANUSCRIPT ACCEPTED BY THE SocIETY OcrOBER 9, 1989

•

Printed in U.S.A.

116

ROADLOG

DAY 1 Saturday, May 22

0.0 0.0 Leave Maritime Inn at intersection of Egg Harbor Road (Business 42-57) and N 14th Avenue. Follow Busines 42-57 southwestward to downtown Sturgeon Bay.

1.1 1.1 Turn right onto N 3rd Avenue and pass shipbuilding facilities on the left. Sturgeon Bay has long had a close association with ships and has been one of the largest shipbuilding ports on the Great Lakes. Long before the railroad into Sturgeon Bay (which passed into oblivion many years ago) was constructed, the area was dependent on water transportation. The first shipbuilding business began in the 1880s, and severa! other companies subsequently located here. During World War 1, the Leatham and Smith Company built tugboats. During World War JI, the company employed 5,000 'Vorkers in three shifts building patrol boats for the U.S. Navy. The Sturgeon Bay Shipbuilding and Dry Dock Company employed 1,600 men in three shifts building supply ships, cargo ships, tugs, and retrieving vessels. The Peterson Boat Works, with 350 employees, launched seventeen 110-foot submarine chasers, eight 85-foot high-speed aircraft rescue vessels, and other ships. AH types of boats have been constructed in Sturgeon Bay, includingfreighters, gilnboats, tugs, luxury yachts, tuna boats, and hydrojets. In recent years, however, the shipbuilding industry has' suffered a significant decline; the Bay Shipbuilding Company, for example, now employs only a skeleta! work force.

1.5 0.4 The huge crane of the Bay Shipbuilding Company is the largest of its kind in the world. Continue on N 3rd Avenue past entrance to Maritime Museum and Sunset Park on the left.

2.1 0.6 N 3rd Avenue becomes County Trunk Highway B. Continue ahead on B.

2.8 0.7 Junction with County BB (Gordon Rd.). Continue ahead on County B.

4.8 2.0 Abandoned quarry in Silurian dolomite on righl.

6.1 1.3 Ruins of loading and shipping facilities on left. View beyond (SW) is across the head of Sturgeon Bay to Idlewood, a large spit. Government Bluff in Potawatomi Statll Park is the high bluff beyond.

6.2 0.1 Note large abandoned quarry in Silurian dolomite on the right, most of which cannot be seen from the road. This quarry was opened in 1893 and ceased operation in 1944. Stone quarrying in the Sturgeon Bay area began in 1832 and once was a major industry. Stone was shipped on barges to severa! Lake Michigan ports, including Milwaukee and Chicago, chiefly for use in harbor construction.

For the next severa! miles our route will foHow a!ong or near the base of tbe Niagara Escarpment on a relatively undissected wave-cut terrace of the Nipissing phase.

6.9 0.7 Enter unincorporated village of Little Harbor.

117

9.0 2.1 STOP 1, Abandoned Chateau Hutter golf course. SWl/4 SEl/4 seco 31, T. 29 N., R. 26 E.; Idlewild 7.5-minute quadrangle.

Note Ihe Nipissing shoreline about 300 m (1,000 feet) to Ihe east and a higher terrace tread, perhaps Ihe main Algonquin, behind it, wilh Ihe Niagara Escarpment beyond Ihat. Why does Ihis upper surface descend soulhward wilh such a high gradient?

9.4 0.4 Turn right (E) onto W Carlsville Road and ascend to upland surface.

11.6 2.2 Stop sign. Junction wilh Wisconsin Highway 42 in small village of Carlsville. Turn left (N) onto Highway 42. Note Door Peninsula Winery in old schoolhouse at northeast corner of intersection.

Highway 42 traverses Ihe till-veneered bedrock upland at a general elevation of about 229 m (750 feet). The drift nearly everywhere is less Ihan 3 m (10 feet) Ihick.

13.9 2.3 Highway descends into a wide, shallow NW-SE-trending linear bedrock lowland Ihat was possibly submerged durihg Ihe main or highest A1gonquin phase.

17.8 3.9 Begin descent into village of Egg Harbor into another NW-SE-trending bedrock lowland (Fig. 1).

18.5 0.7 Turn left near bottom of hill onto Soulh Trail and contÍl¡ue descent past exposures of Silurian dolomite on Ihe left.

18.9 0.4 Stop sign. Turn right onto County G (Horseshoe Bay Road).

The road follows Ihe crest of a gigantic bar or beach ridge at Ihe head of Egg Harbor Iha! was built across a deep bay of Green Bay (Fig. 1). Bolh Chamberlin (1877) and Goldlhwait (1907) were much impressed by Ihe size of Ihis bar. Goldthwait (1907, p. 89), described it as "probably Ihe most remarkable beach on Ihe Wisconsin shore, a great barrier bar of coarse chipstone which reaches from Ihe village southward across a broad deep valley for half a mile to sorne high limestone ledges. . .. On Ihe eastern side of it a steep slope descends to Ihe swampy valley, and on Ihe western side a1so Ihe ground slopes steeply down to Ihe bay. At a clearing by Ihe road, where Ihe great bar connects wilh Ihe limestone bluff at its soulh end, Ihe form and structure of it are plainly revealed .... The inland slope of Ihe bar is very precipitous, far steeper Ihan ordinary beach slopes;and Ihe lakeward side of Ihe great ridge has been deeply cut into during a 20-foot stage. which is marked by a high cliff and bench, a few rods back from Ihe lake. Large borrow pits expose a tightI y packed mass of discoidal pebbles ofwhite Iimestone, nearly a11 oflhem between Ihree and six inches in diameter and very well rounded' as if by vigorous wave action. While the unusual size of Ihe ridge and its steep slopes suggest Ihat it is an esker ralher Ihan a barrier bar, Ihere is abundant proof of its true nature: -- it joins a wave-cut cliff and bench of rock, at precisely Ihe expected level of Ihe highest shore-Iine; it sweeps around Ihe head of Ihe harbor, where, if anywhere, a barrier would be built; its crest line is quite even; it is made of Ihoroughly waterworn pebbles and chipstone of nearly uniform size, no erratics whatever being seen in Ihe large pit, and containing hardly any sandy or earthly material;' Ihere are distinct beaches on its top and outer slope. Clearly Ihe whole ridge is a shore embankment, built up in deep water across Ihe head of Ihe bay, from headland to headland, to a height of about seven feet aboye Ihe water. The Iimestone cliffs from which Ihe bar tails out have an unusually Ihin-bedded structure and abundant joint planes, affording favorable supply of rock debris to Ihe waves."

118

+ Leroys

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25

Par! of the Egg Harbor 7.5-mi11ute quadrangle map. Seale 1:24,000; contour '\ ,interval 10 feet. Egg Harbor (bay) occupies par! of a NW-SE-trending preglaciai (interglacial?) bedrock lowland. TIte Ni.gam Escarpment here is about 120 feet bigh. Note \ ,,\) '&j:;¡¡ f' ~'~ '[ dle prominent AlgonquinlNipissing terrace below the escarpment and another terrace on top ",;:", \, r ~\~ >o, of lbe escarpment with a possible sboreline at 750-760 feet. Note also the massive gravel bar i at the bead of Egg Harbor lhat \VdS built across par! of a lake plain at 600 feet nt the moutb ;­

of tbis bedrock lowland. Th,e gmvel pit ot lb,e east edge o, f the map is located at the \Vest end~ of a narrow end mom;oe tbal erosses the peninsul. with a general east-west orientation. I e

I ,Jyc .U'~? ~'--~-1 l~-! ): p'~' 00

, I ~" l' l 'r "'"/' , . . I~~c~ __ -, ,.- e I 1" I " ,.

Allhough Goldlhwait infers Ihat Ihe bar was cut into during Ihe Nipissing phase (lhe "20-foot stage") and Iherefore must have built during an earlier phase, it seems possible Ihat it was built eilherin late Nipissing or early post-Nipissing time because Ihe elevation of Ihe area behind Ihe bar (about 183 m or 600 feet) corresponds wilh Ihat of Nipissing terraces elsewhere in Ihe region.

19.3 004 Stop signo Tum left in village of Egg Harbor, rejoining Wisconsin Highway 42.

19.6 0.3 Junction wilh County E from Ihe right. Continue ahead on Highway 42. Retum to upland and note numerous road cuts in Silurian dolomite Ihat attest to Ihe Ihinness of Ihe drift cover.

21.0 lA Junetion wilh County EE. Continue ahead on Highway 42.

22.1 1.1 Small village ofJuddville.

24.6 2.5 Begin deseent into village ofFish Creek. Note eontinuous exposure of Silurian dolomite in road eut on left. The Fish.Creek hill served as a challenge to motorists during Ihe early days of Ihe automobile; Ihe road gradient has been lowered several times during Ihe past 60 years.

25.2 0.6 Stop sign at bottom of hill. Tum right (E). Fish Creek is built mostIy on a wave-eut platform formed during Ihe Nipissing and Algoma phases. Goldlhwait (1907, p. 88) identified eight shorelines in Fish Creek, ranging from 4 feet to 59 feet aboye modero lake level (Fig. 2). The highest and strongest of Ihe lower beaehes, at 21 feet aboye Ihe bay, is a "eoarse ridge of shingle" Ihat undoubtedly represents Ihe Nipissing phase.

EPHRAIM

.----ALGONQUIN 54 56 59/

39......--33

1----16 21 NIPISSING---l 4

FISH CREEK Figure 2. Topographic. profiles showing multiple abandoned shorelines at Fish Creek and Ephraim. Figures are in reet aboye lake leve!. Note that the main A1gonquin beach is about 3 feet higher at Ephraim than at Fish Creek, but that the elevation of the Nipissing beach is constant. (Adapted from Goldthwait, 1907, figs. 30 and 31.)

120

•

25.7 0.5 Turn left onto Shore Road and enter Peninsula State Park (Fig. 3).

25.8 0.1

26.2 0.4

26.7 0.5

27.2 0.5

27.8 0.6

Peninsula State Park is one offue gems offue Wisconsin state park system. The park is one of fue oldest, largest, and most popular parks in fue state. It is also one of fue most scenic parks in fue state, 'which partly explains why it attracts more fuan ,?ne million visitors annually. Alfuough 77% of fue park's 3,763 acres is designated low-use natural area, fue park is clearly a major recreational center. Four family campgrounds provide 472 campsites, 100 of which have electrical hookups. AH family campgrounds now have flush toilets and laundry facilities (tubs) fuat are open from early May furough mid-October; pit toilets are available furoughout fue year. The park contains 20 miles of paved roads, 20 miles of hiking trails, 19 miles of cross-country ski trails, 17 miles of snowmobile trails, 9 miles of bieycle paths, a fine sand beach and bath house, a nature center and nature program, a vita course, a historie 125-year old lighfuouse, playground equipment, a tennis court, and one of fue most beautiful and challenging l8-hole golf courses in fue U.S.

Stop signo Pass contact station and continue ahead on Shore Road.

Cross causeway between Weborg Marsh and Green Bay. Village of Fish Creek across harbor to fue left.

Nelson Point picnic area on left. Note low Nipissing beach ridge on fue right. Shore Road follows fue Nipissing shoreline for a considerable distance . . Turn right onto Skyline Road. Cross beach ridge and ascend to upland.

PHOTO STOP, Sven's Bluff overlook atop the Niagara Escarpment. The escarpment here rises about 49 m (160 feet) aboye Green Bay. The fureeislands directly to fue west are called· fue Strawberry Islands; from left to right, fuey are Adventure Island, Little Strawberry Island, and Jack Island. The larger island in fue middle distance is Chambers Island. The Upper Perunsula of Michigan is in fue far distance.

Throughout much of fue Door Peninsula, fue Green Bay shoreline is characterized by steep dolomite bluffs and by pebble or cobble beaches. These features are especially characteristic of fue shoreline north of Sturgeon Bay in northern Door County, as here at Svens Bluff. Till bluffs are absent and sand beaches are rare features of fue Green Bay shoreline.

Continue ahead 01). Skyline Road, which follows fue crest of fue Niagara Escarpment.

28.5 0.7 Turn left onto Hernlock Road, which descends a preglacial valley reentrant in fue escarpment (Fig. 4).

Alfuough cornmon1y categorized as northern hardwood forest, fue vegetation here actually consists of bofu hardwoods and conifers. The main species inelude sugar maple, white birch, American beech, oak, ironwood, aspen, northern white cedar, white pine, red pine, hernlock, and balsam fir. Two areas of fue State's "Natural Area" system managed by fue State Natural AreasCouncil are included in fue park and serve as outdoor laboratories for research and nature study. These are fue Peninsula Park White Cedar Forest and the Peninsula Park Beech Forest.

28.9 0.4 Note low beach ridge on fue right.

121

Oreen Bay

ROUTE MAP PENINSULA STATE PARK

WlSCOI1Sin Department oC Nalma1 Resourees P.O. Box218

F'OO Creek, WI 54212 (414)868-3258

CAMPGROUND MAPS " INFORMATION

Nlcofer Bar

LEGEND Park Boundary Paved Road Hlklng Trall

¡ I

Vlta Coursa Blke Trall Aouta Roek Qulerop Vista Picnic Atea Amph1thealer Phone Campground Group Campground

Stale Natural A. oVe, _ - -- - Nor1h

Figure 3. Map of Peninsula State Park showing location of Photo Stop and Stop 2. Arrow heads show direction of field-trip route through the park.

29.0 0.1 Stop sign. Turn right onto Bluff Road and note beach ridge on right-hand side of road.

29.2 0.2 Stop sign at junction wilh Shore Road; continue ahead on Shore Road.

29.3 0.1 Note wave-cut bluff on right.

30.0 0.7 Junction wilh Skyline Road. Continue ahead on Shore Road.

30.2 0.2 Eagle Bluff vista on left.

30.4 0.2 Eagle Tower atop Eagle Bluff at lhe entrance to Eagle Harbor. Eagle Bluff rises nearly 58 m (190 feet) aboye water leve!. Maximum water deplhs irnmediately to lhe north exceed 18 m (60 feet), lhus making lhe escarpment about 76 m (250 feet) high. Farther to lhe north, lhe water is about 24m (80 feet) deep, except near shoals oc- reefs.

Bear left just beyond Eagle Tower, leaving Shore Road and following road to Eagle Terrace picnic area.

30.5 0.1 STOP 2, Eagle Terrace. NEl/4 SEl/4 seco 15, T. 31 N., R. 27 E.; Ephraim 7.5-minute quadrangle.

Park on right side of road in first small parking area, which is situated on a bedrock terrace. Rest facilities are located on top of a low bedrock cliff lhat is eilher part of a preglacial valley wall or more probably a wave-cut cliff. The elevation at lhe base of lhe cliff, however, is at least 36 m (120 feet) higher lhan lhat of lhe rebounded main Algonquin shoreline at lhis latitude.

Walk down !he road to lhird parking area and descend stairway to Eagle Terrace overlook, which is lhe site of an old quarry. Eagle Harbor is one of lhe finest harbors along lhe Green Bay shoreline, and during lhe surnmer monlhs it is lhe site of numerous recreational activities, particularly sailing. Across lhe bay is lhe village of Ephraim, which for many years was considered to be lhe Midwest capitol of lhe Flying Seot.

Eagle Harbor and lhe Ephraim Swamp beyond (Fig. 4) occupy lhe west end of a major bedrock valley lhat crosses lhe peninsula from northeast to soulhwest (Sherrill, 1978). It is one of at least four such valleys, a11 of which were probably cut by preglacial streams lhat f10wed soulheastward toward Lake Michigan (Martin, 1916). Baileys Harbor, Moonlight Bay, and lhe Baileys Harbor Swamp occupy lhe lhe dowstream end of lhe valley on lhe Lake Michigan side of lhe peninsula. Jt seems likely lhat lhe valley was scoured and enlarged by advance tongues of ice (valley glaciers, in a sense) from lhe Green Lobe prior to general glaciation of lhe upland in late Woodfordian time. However, no glacial striae have yet been found on lhe sides of lhe valley to verify lhis hypolhesis; perhaps lhey have been destroyed by intensive frost wedging following lheir formation. Subsequent to glaciation lhe Ephraim-Baileys Harbor lowland was completely submerged during bolh lhe main Algonquin and Nipissing phases. A1lhough lhey have not been traced continuously across lhe peninsula, shorelines mapped by Thwaites and Bertrand (1957, PI. 8) have been largely confirmed.

Note lhe notches or steps in lhe bedrock headlands to lhe northeas!. Allhough one unfamiliar wilh lhis area might easily interpret lhe terraces as stripped surfaces on more resistant bedrock units, lhey are indeed levels oflate glacial and early postglaciallake phases -- as Goldlhwait (1907) long ago concluded.

123

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+

. STOP 2

Figure 4. Part of!he Ephraim 7.s-minute quadrangle map. Scale 1:24,000; contour interval 10 feet. Eagle Harbor and !he Ephraim Swamp occupY par! of a preglacial bedrock lowland. Note tbe high shoreline bluffs, up to 180 feet high, !hat define the Niagara Escarpment; a preglacial reentrant in the escarpment; wave-cut terraces (for example, at !he Peninsula Golf Club); and tbe Nipissing shoreline at 600 feet.

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Return to vehicles and, if time permits, climb Eagle Tower for a spectacular panoramic view of the landscape.

Continue south on Eagle Terrace road.

30.7 0.2 Stop signo 'Turn left and rejoin Shore Road.

31.0 0.3 Descend slope 0I1to bedrock terrace on which the lower part of Peninsula State Park golf course is built (Fig. 4). The elevation of this terrace is 6-12 m (20-40 feet) higher than that of the uplifted main AIgonquin and is terminated on the bay side by a steep wave-cut cJiff that is a1most certain1y AIgonquin. Is the terrace a pre-AIgonquin wave-cut platform or a stripped surface (preglacial?) on a resistant bedrock unit? Continue along Shore Road and note probable wave-cut cJiff on right side of road.

31.8 0.8 Stop signo Turn left (NE) onto Wisconsin Highway 42.

31.9 0.1 Descend hill into Village of Ephraim onto broad Nipissing and post-Nipissing surface at the head of Eagle Harbor and continue around the bay part way through the village.

Ephraim was, and to a large extent still is, the quaintest and most conservative village in Door County. It has been called "The Pearl of the Peninsula," "A Village of Values," and "The Resort Center of Door County." Until relatively recently, all buildings in the village were required to be painted white and, in contrast to the remainder of Door County, the village has a1ways been dry. As recently as 1992, the residents rejected a referendum that would have a1IOWed wine to be served with meals in the local eating places.

Ephraim was fourided in 1853 by a group of Moravians, including the Reverend Andrew Iverson, Ole Larson, and other Scandinavians. The big event of the year is the Fyr Bal Festival, held every June to celebrate the burning of the winter witch and the beginning of summer. The event is cJimaxed by the crowning of the Fyr BaI Chieftan -- a distinguished Ephraim citizen selected by vote of village residents -- who lights the first of many bonfires around the shore.

The early industry of Ephraim was the production of cedar fenceposts, but like the remainder of Door County the village gradually evolved into a major tourist community.

33.0 1.1 Turn right (E) onto County Trunk Q (Church Sto). Cross the ill-defined Nipissing shoreline and ascend hill to base of wave-cut cliff.

33.2 0.2 Stop signo Turn left (N) onto Moravia St. and proceed northward just below the uplifted AIgonquin shoreline. Note wave-cut cliff on right, which is pocked by numerous shallow sea caves.

33.4 0.2 Stop signo The road ahead follows the crest oh distinct 9-m (30-foot) ridge -- probably a massive gravel bar similar to that traversed just south of Egg Harbor. Turn right onto Anderson Lane and ascend about 24 m (80 feet) onto the upland surface.

33.7 0.3 Bear left at Y-intersection with Norway Lane and continue around curve to right onto Settlement Road.

125

34.3 0.6 Stop signo 1ntersection of Settlement Road with Townline Road. The elevation of the upland in this area is from 46 to 52 ni (150 to 170 feet) aboye modern lake leve!.

STOP 3, Fresh road cut in Liberty Grove tilI on south side of' Settlement Road immediately east ofintersection with TownlineRoad. NW1/4 SW1I4 seco 18, T. 31 N., R. 28 E.; Ephraim 7.5-minute quadrangle.

Here, as in most places, Liberty grove tUl is a very stony, strongly calcareous loam till containing a high percentage of dolomite cJasts. 1t is just slightly less sandy and more silty at this site than typical. Grain-size analyses of the matrix (less than 2 mm) of two samples from this location average 46% sand, 42 % silt, and 12% clay. Here, also as in most places, the till is brown (7.5YR 5/4) to yellowish brown (lOYR 5/4); note, however, that it has a very weak pink or salmon tinge, which possibly reflects a high content of magn'esium from ground-up dolomite. No clay-mineral data are available for this location. Note also that bedrock is present at the very base of the exposure at the west end of the cut. This drift was first called Liberty Grove till by Schneider (1981) and soon thereafter was formally named the Liberty Grove Member of the Horicon Formation (Mickelson and others, 1984); the latter has recently been renamed the Holy Hill Formation (Mickelson and Syverson, in press). Liberty Grove till was deposited during late Woodfordian time by ice of the Green Bay Lobe, which crossed the upland of northern Door County with a flow direction of S S-2()<, E, as indicated by both striae and drumlin axes. The thinness of the till coupled with low exposures virtually precludes reliable fabric analyses.

The Liberty Grove till correlates with Mapleview till on the west side of the Green Bay 10wJand and with New Berlin till of southeastern Wisconsin. Thwaites and Bertrand (1957) mapped it as till of the Cary Substage.

Turn left (N) onto Townline Road. Proceed past the new Ephraim wastewater treatment facility on the left. Mandated by the State to do so, many of the villages in Door County (including Baileys Harbor, Egg Harbor, Ephraim, and Fish Creek) have recently completed the installation of municipal sewer systems and the construction of sewage trearment plants.

35.3 1.0 Stop signo Turn right (NE) onto Wisconsin Highway 42.

35.4 0.2 Turn left onto Little Sister Hill Road.

35.6 0.2 Stop signo Turn left onto PebbleBeach Road.

35.7 0.1 Turn left into Little Sister Cemetery.

35.8 0.1 STOP 4, Little Sister Bay and Pebble Beach. NW1I4 NW1I4 seco 7, T. 31 N., R. 28 E.; Ephraim 7.5-minute quadrangle.

Walk along base of bedrock cliff 10 north end of cemetery, then eastward to road, down the road to a strong cobble beach ridge, eastward along the path at crest of this ridge for a few hundred feet, through the woods lo the beach, then westward along the beach, and return lO vehicles through the woods or along the east side of the road. How many beach ridges are present between the modern shoreline and the strong cobble beach? How many between this cobble beach and the cemetery?

126

Little Sister Bay is tbe site of a cIassie study of a pebble beaeh environment, involving statistieal analyses of pebble size, roundness, and sphericity, during tbe middle 1930s by Krumbein and Griffitb (1938). Pebble Beaeh is also weIl known, indeed famous, to non-geologists for its smootb weIl-rounded beaeh pebbles. TItousands of homes tbroughout tbe world utnize stones from here as paperweights. Cornmonly tbe pebbles have hand paintings or decals of eherries or Christmas items on tbem, and for many years tbey were widely sold as souvenirs of Door County.

TIte erest of tbe strong beaeh ridge is about 6 m (20 feet) aboye lake leve!. Botb its elevation and its eharaeter lead to tbe inevitable eoncIusion tbat it is tbe Nipissing beaeh. Several of tbe higher ridges, tberefore, must represent late Algonquin (Le., post-main AIgonquin) phases formed during periods of stability as lake level was dropping to tbe low-water Chippewa phase.

TIte bedroek cliff is interpreted as a wave-eut cliff. TIte base of tbe bluff is between 206 and 207 m (675 and 680 feet) elevation, or about 30 m (100 feet) aboye lake leve!. TItus it appears to be much too high for tbe rebounded AIgonquin shoreline, which Goldtbwait (1907) and otber workers placed at about 196 m (644 feet) at tbis latitude. Is it a pre-Algonquin cliff or has tbe Algonquin shoreline rebounded more tban previously believed?

35.9 0.1 Stop sign at intersection of Pebble Beach Road and Little Sister Road. Continue ahead on Pebble Beach Road and bear left at Y -intersection.

36.1 0.2 Stop signo Turn left (NE) onto Wisconsin Highway 42.

37.1 1.0 Begin descent into village of Sister Bay.

37;2 0.1 Junetion of Wisconsin Highways 42 and 57. Continue ahéad tbrough village of Sister Bay.

Sister Bay has long been tbe most progressive village north of Sturgeon Bay, serving as tbe cornmercial and residential center of tbe northern part of Door County. Whereas otber villages have only recently bunt sewers and wastewater treatment plants (by State mandate), Sister Bay has had municipal sewer and water facilities for many years and recently tripled tbe capaeity of its sewage-treatment facilities.'

37.7 0.5 Turn right (E) at Bhirdo's Union 76 onto Scandia Road one short block past tbe marina. Witbin tbe next half-mne cross two, possibly tbree, shorelines and rise back onto tbe till-veneered upland surface. TIte lower shoreline, at nearly 183 m (600 feet), is interpreted as tbe Nipissing. TIte middle shoreline, at about 195 m (640 feet), is interpreted as tbe uplifted Algonquin; low roadcuts in tbe area at or just below tbis elevation have revealed tbe presence of lacustrine sediments. TIte upland is underlain by tbin Liberty Grove till; note low roadcuts in tbe coarse-grained til!.

39.0 1.3 Stop signo Turn left (N) onto Old Stage Road, continuing across tbin ground-moraine upland underlain by Liberty Grove till.

39.5 0.5 Turn right (E) onto HiII Road at Sister Bay Moravian Church cemetery and enter tbe Liberty Grove drumlin field (Fig. 5).

40.7 1.2 Note roadeuts tbrough drumlins, exposing Liberty Grove tn!.

41.0 0.3 Stop signo Turn left (N) onto County Trunk ZZ. Note NNW-SSE orientation of drumlin axes.

127

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41.3. 0.3 Note "Drumlin Place" sign at home of WiIliam Christiansen on right. Drumlin landscape to the left.

41.5 0.2 Turn right (E) onto Waters' End Road.

41.9 0.4 Cross the Algonquin shoreline. The Algonquin beach in this area is marked by a discontinous string of abandoned gravel pits at an elevation of 195-198 m (640-650 feet).

42.3 0.4 Cross the Nipissing shoreline. The Nipissing beach in this area is marked by sand dunes at an elevation of about 183 m (600 feet).

42.4 0.1 Turn left (N) onto Sand Bay Lan~ North.

42.6 0.2 Turn right into Sand Bay Town Park for LUNCH STOP.

Retrace route southward to Waters End Road and then westward to County ZZ, recrossing the Nipissing and Algonquin shorelines.

44.0 1.4 Stop signo Junction with County Trunk ZZ. Continue ahead on Waters End Road.

44.1 0.1 STOP 5, Krumenacher drumlin and Liberty Grove till. SE1I4 NWI/4 seco 35, T. 32 N., R. 28 E.; Sister Bay 7.5-minute quadrangle.

Examine till in road cut and then walk northward along crest of drumlin on property owned by Carol and Fred Krumenacher. Please be careful of both seedlings and fox holes.

This. road cut was designated as the type section oí the Liberty Grove Member of the Horicon Formation by Schneider (in Mickelson and others, 1984). The Liberty Grove here is very similar to that examined at Stop 3: it is a strongly calcareous brown (7.5YR 5/4-IOYR 5/3) stony loam till in which the matrix (less than 2 mm) contains 47% sand, 39% silt, and 14% clay. The el ay-mineral assemblage is.16% expandables, 67% iIlite, and 17% kaolinite plus chlorite. Samples from two drumlins one-half mile to the south have nearly identical average compositions of 52% sand, 38% silt, and 10% c1ay in the matrix and 15% expandable minerals, 67 % iIlite, and 18 % kaolinite plus chlorite.

The Liberty Grove drumlin field (Fig. 5) is a small but distinct group of low drumlins whose long axes trend afew degrees east of soulh. Many of the hills are only lO to 20 feet (3 to 6 m) high, although a few of the more prominent forms have relief of 30 to 40 feet (9 to 12 m). The orientation of the long axes of these drumlins averages about S. 15° E. Several of these features, inc1uding the Krumenacher drumlin, display distinctiy asymmetric longitudinal profiles, having steeper north-facing (up-ice) slopes.

The Liberty Grove drumlins were initially mapped and described by Kowalke (1952), and they are also shown on the glacial map of Ihe Door Peninsula by Thwaites and Bertrand (1957, pI. 8). In neither of these papers, however, do we find interpretive statements regarding the origin of the drumlins or their relationship to the regional glacial history. The current interpretation (Schneider, 1981, 1989, 1990a) is that both the morphology and composition of the features are the result of the advance of the Green Bay Lobe in late Woodfordian time.

Continue westward Ihrough the drumlin field on Waters End Road.

129

45.5 1.4 Stop signo Turn right (N) onto Old Stage Road.

46.0 0.5 Stop signo Turn right (E) onto Wildwood Road (County Trunk Z).

46.4 0.4 Note the low, narrow recessional moraine on the left (N) side of the road (Fig. 5), .which nearly parallels the road for sorne distance eastward and marks the northern extent of the Liberty Grove drumlins. Although the signifcance of the moraine is not known, it appears to truncate the drumlins and therefore may represent a minor readvance of the ice.

47.0 0.6 Turn left (N) onto Lakeview Road. Cross the low end moraine and continue northward. Drumlin field to the south.

47.5 0.5 T-junction with Méadow Road from the east. Continue ahead toward the highest part of northern Door County.

48.0 0.5 Junction with Highview Road. Continue ahead on Lakeview Road.

48.6 0.6 Note exposure of dolomite bedrock on the left. This is interpreted as part of a former wave-cut cliff. The terrace associated with this lake stage is apparently truncated immediately east of the road by a slightly lower surface. Several high-level shorelines have recently been recogruzed in the Ellison Bay area (Figs. 5 and 6), but the correlation of virtually all ofthem is unclear.

Begin step-like descent into village of Ellison Bay, crossing several additional abandoned shorelines and associated terraces. The lake stages responsible for the formation of these features have not been identified:

49.5 0.9 Stop signo Turn left (NW) onto Mink River Road at the Nipissing shoreline.

49.6 0.1 Stop signo Turn left (SW) onto Highway 42 and proceed through the village of Ellison Bay. Near the south end of the village, cross several old shorelines arid ascend to the upland surface.

50.3 0.7 Note prominent riser to the south with a row of poplar trees on the top (Fig. 5). The base of the riser is interpreted as a probable water plane. The riser can be traced directly to the highest wave-cut cliff on Highview Road (mile 48.6) .. This apparent shoreline occurs at an elevation of226-229 m (740-750 feet), or nearly 30 m (100 feet) higher than the presumed elevation of the uplifted AIgonquin shoreline at this latitude; the Algonquin shoreline has generally been assumed to be the highest shoreline in the area.

Similar appearing, but less impressive, features at approximately the sarne elevation (750 feet) occur farther south in northern Door County. These latter features cannot logically correlate with the shoreline at this locality, however, assuming a reasonable arnount of mirthward-increasing isostatic rebound. The more southern features are probably stripped surfaces on more resistant layers in the bedrock. Perhaps they are schichttreppen (see paper by Stieglitz and Schuster elsewhere in this guidebook).

50.5 0.2 Turn right (W) onto Porcupine Bay Road.

51.3 0.8 Turn right (N) onto Ellison Bluff Road, shortly after crossing beach ridge at about 226 m (740 feet). Follow Ellison Bluff Road 10 Ellison Bay Bluff County Park.

130

52.4 1.1 STOP 6, ElIison Bluff County Park. NW1I4 NW1I4 seco 16, T. 32 N., R. 28 E.; Ellison Bay 7.5-mimute quadrangle.

TIte rugged character of the Green Bay shoreline, with its high dolomite bluffs and rubbly beaches is well displayed here at Ellison Bluff. Por a spectacular view of the Green Bay shoreline, descend the stairway to the observation platform. TIte view is southwestward along the dissected and partially submerged Niagara Escarpment on the west side or antidip slope of the Niagara Cuesta. Tbe large island is Chambers Island, and the smaller islands are Horseshoe (Eagle) Island and the Strawberry Islands. Across Green Bay to the west and northwest is the Upper Peninsula of Michigan.

In terms of its height and general topographic express ion, Ellison Bluff is typical of the many high dolomite bluffs that characterize the modern Green Bay shoreline along the Niagara Escarpment in northern Door County. In fact, none of the bluffs display the character of the shoreline any better than Ellison Bluff, although several are probably better known. ElIison Bluff rises about 55 m (180 feet) aboye the level of Green Bay. Tbe full height of the escarpment is not visible, however, because the lower part is submerged beneath the water plane. Water depths not far offshore cornmonIy exceed a little over 30 m (100 feet); thus the full height of the escarpment probably exceeds 76 m (250 feet), and in sorne places it may approach 91 m (300 feet).

Remnants of at least one and possibly two high-Ievel abandoned shorelines pass through the park. TIte most apparent of these is a low wave-cut cliff directly behind the old well site. TIte base ofthe cliffhas an elevation of approximately 233 m (765 feet), or about 56 m (185 feet) aboye modern lake leve!. Correlation of this feature with the established history of late-glacial and postglaciallake phases in the Lake Michigan and Green Bay basins is not possible, however. Tbe highest abandoned shore feature of known correlation is the uplifted AIgonquin shoreline, which in this area has an altitude of about 198 m (650 feet), or well over 30 m (lOO feet) below the wave-cut cliff at the top of ElIison Bluff.

Question. Is the low cliffbehind the picnic area correctly identified? Is it indeed a wave-cut feature? Does a cobble beach possibly exist at its base? Or is the cliff instead an erosional feature related to preglacial stream dissection of the dolomite upland? Was it produced mainIy by frost shattering or onIy modified by frost action? Although the answers are not particularly critical at this specific location, the problem is illustrative of one of the problems that exist in the northern Door Peninsula in identifying remnants of abandoned shorelines.

Retrace route to Wisconsin Highway 42 via ElIison Bluff Road and Porcupine Bay Road.

54.2 1.8 Stop signo Note again the apparent high-Ievel shoreline and wave-cut slope directly ahead and to the southeast. Turn left (NE) onto Wiseonsin Highway 42.

54.5 0.3 Begin deseent into vi)Iage of ElIison Bay. Note notched eharacter of bluffs in the distance to the north.

55.3 0.8 Turn left (N) onto Garret Bay Road.

55.5 0.2 Entrance to TIte Clearing on left. Tbe Clearing is a unique adult education center offering non-eredit courses in Iiterature, philosphy, religion, foreign language, music, arts, erafts, and nature study. Tbe name refers not to a meadow or open space but to "a clearing ofthe mind. n It was founded in 1935 by Danish-born landseape architect Jens Jensen at age 75,

131

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severa! places by gravel pits .. Virtuallyall sand and gravel in northem Door County is ,1 =' 'V rO ~ I obtained from beach deposits, especially those deposited during tbe Algonqilinstage, which

on Ibis map is identified generally by the 6S0-foo! contour lineo

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who is better remembered as head of Ihe Chicago Park District and Ihe inspiration behind Cook County's Forest Preserve District.

56.6 1.1 Junction wilh Maplewood Road from Ihe left. Continue ahead on Garret Bay Road.

57.4 0.8 Turn left ry.t) onto Door Bluff Road.

57.5 0.1 Turn right onto Door Bluff Park Road and proceed to Door Bluff County Park.

58.3 0.8 Cross highest abandoned beach ridge.

58.5 0.2 STOP 7, Door Bluff County Park at Death's Door Bluff. NWl/4 NEl/4 seco 35, T. 33 N., R. 28 E.; EIlison Bay 7.5-minute quadrangle.

Dealh's Door Bluff is at Ihe western end of Dealh's Door or Porte del! Morts, Ihe passage Ihat separates Ihe waters of Green Bay from Lake Michigan. Dealh's Door was named by Ihe Indians long before Ihe French arrived. Because of unusually strong currents and at times strong winds Ihat characterize Ihe strait, an unknown number of ships have foundered or been driven ashore. At least eight large vessels were wrecked or stranded here in one week in September, 1872.

FoIlow palh down to water level across Ihree prominent wave-cut cliffs cut into Ihe dolomite. It is unlikely Ihat differential resistance of Ihe bedrock has exerted any control over Ihe formation of Ihese cliffs. How many shorelines or lake phases are represented by Ihese cliffs (certainly more Ihan Ihree), and how do Ihey correlate wilh Ihe beach ridges at Little Sister Bay and elsewhere? Note exceIlent examples of joint-controIled rockfaIls from lowest cliff onto Ihe beach.

Goldlhwait (1907, p. 81, 85, 103) was much impressed by Ihe wave-cut cliffs Ihat form Ihe notched or stepped headlands at Ihe north end of Ihe peninsula, especially those here at Dealh's Door Bluff.He remarked Ihat Ihe steps are " ... so strongly outlined Ihat Iheir wave-cut origin was at first hard to believe. Qne would be indined to refer them to structural differences on Ihe bed rock, emphasized by wealhering; but cIoser examination and comparison wilh Ihe present cIiffs left no doubt regarding Iheir true nature. These great step-like notches . . . are Ihe deeply engraved high water marks of an extinct Lake Michigan, or more accurately of Lake AIgonquin and Lake Nipissing."

At Hedgehog Harbor, immediately to Ihe east (Fig. 6), Goldlhwait identified six abandoned shorelines -- at 7, 22, 46, 62, and 79 feet aboye modern lake leve!. The highest, a cobblestone bar at 200 m (658 feet) elevation, was interpreted as Ihe highest (main) A1gonquin. If Goldlhwait's measurements and uplift curve are indeed correct, Ihe main AIgonquin shoreline has rebounded about 12 m (40 feet) between here and Sturgeon Bay.

Retrace route to EIlison Bay, foIlowing Door Bluff Park Road, Door Bluff Road, and Garret Bay Road.

61.6 3.1 Turn left (E) onto School Road.

61.8 0.2 Stop signo Rejoin Wisconsin Highway 42 and proceed eastward.

133

ROUTE

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WELCOME TO NEWPORT STATE PARK

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Figure 7. Map of Newport State Park showing loeation of Stop 8 and Europe Lake. Arrow heads show direction of field·trip route.

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62.1 0.3 The highway descends into a conspicuous north-soulh bedrock trough (Fig.6), which was apparently occupied during several phases oflake history in late-glacial and postglacial time. The road crosses Ihe Nipissing shoreline on bolh sides of Ihe trough and rises eastward to Ihe uplifted Algonquin shoreline at 198 m (650) feet at Ihe intersection wilh Blackberry Road. The elevation at Ihe bottom of Ihe trough is somewhat below 181 m (595 feet).

63.8 1.7 Highway 42 curves to Ihe left (N). Continue straight ahead (E).on Europe Bay Road (Fig. 7).

64.5 0.7 Stop signo Junction wilh Timberline Road. Continue ahead on Europe Bay Road.

64.7 0.2

65.5 0.8

65.7 0.2

Cross Ihe Algonquin beach, marked by inactive gravel pits on both sides of the road.

Cross Ihe Nipissing shoreline, marked by sand dunes.

STOP 8, Europe Bay and Europe Lake, Newport State Park and Ferdinand Hotz Town Park. NWl/4 NWl/4 seco 16 and SWl/4 seco 9, T. 32 N., R. 29 E.; Washington 1sland 7.5-minute quadrangle.

Newport State Park (Fig. 7) is open year-round for recreation and camping. Unlike Peninsula State Park, however, Newport is a semi-wilderness park. In contrast wilh Peninsula, wilh its nearly 500 campsites and flush toilets, Newport has only 16 campsites, all of which are primitive and can only be reached by backpacking. The closest site is 1.5 km (0.9 mile) from Ihe park road, Ihe farthest 5.6 km (3.5 miles). Drinking water must be carried in to Ihe campsites and only pit toilets are available. The park has more Ihan 45 km

. (28 miles) of shoreline and inland hiking trails. Cross-country skiing is stronglyencouraged; snowmobiles are prohibited.

During Ihe 1800s, Newport was a logging village -- one of several small "pier cornmunities" in northern Door County Ihat centered around long piers Ihat stretched into Lake Michigan and Green Bay. Great Lakes schooners docked at Ihese piers to load cordwood and Christmas trees bound for Lake Michigan ports in Wisconsin, Illinois, and Michigan. Large logs found on Ihe beach are aH Ihat remain of Newport's long pier and white pine foresto Por a short history of Newport Village, see paper by Coggin Heeringa, Ihe park naturalist, elsewhere in Ihis guidebook.

The modern shoreline here contrasts strongly wilh Ihat on Ihe west side of Ihe Door Península. Whereas high bedrock bluffs and cobble beaches are characteristic of the Green Bay shoreline, Ihe Lake Michigan shore is, in general, characterized by gentle slopes, extensive sand beaches, dune complexes, and comparatively few exposures of bedrock.

Europe Bay (Fig. 8) is Ihe northernmost bay on Ihe Lake Michigan side of Ihe peninsula. 1t is a broadly arcuate feature, at least by comparison wilh many oflhe bays Ihat characterize Ihe Door County shoreline. As measured along Ihe lake shore, Ihe bay is about 4 km (2.5 miles) long. Much oflhe shoreline Ihroughout Ihis distance is characterized by a wide sandy beach, bordered on Ihe west by low sand dunes. No bedrock is known to be present in Ihis central part of Ihe bay. The points or headlands Ihat define Ihe northern and soulhern limits of Ihe bay are composed of bedrock, however -- dominantly Ihin-b~ded Silurian dolomite wilh nodules or interbeds of chert. As Ihese headlands are approached, Ihe sand beaches narrow and disappear, passing into pebble or cobble beaches near Ihe bedrock headlands.

135

Europe Lake is located a short distance behind (west oí) tbe nortbern half of Europe Bay, and is separated from Lake Michigan by tbe bedrock headland (on tbe nortb) and a moderately large dune complex (on tbe soutb). Europe Lake is tbe smallest of only tbree large inland lakes in Door County, tbe otber two being Kangaroo Lake southhwest of Baileys Harbor and Clark Lake south of Jacksonport. The formalion of all tbree lakes appears to be similar.

Europe Lake is a shallow medium-size lake witb a maximum deptb of 3 m (10 feet). It is about 1,450 m (4,750 feet) long from nortb to soutb, 1,250 m (4,100 feet) wide from east to west, covers an area of 273 acres, and has a shoreline perimeter of nearly 5.5 km (3.4 miles). The surface of tbe lake is about 6 m (20 feet) higher than Lake Michigan, at an elevation of 183 m (600 feet).

Almost certainly, tbe area now occupied by Europe Lake was formerly part of Europe Bay -- a larger and more deeply indented Europe Bay. Both Europe Lake and Europe Bay appear to occupy a bedrock lowland, possibly a preglacial valley, located between tbe dolomite headlands that form tbe horns of tbe bay. The area of tbe lake was slowly sealed off by tbe growtb of a baymoutb bar built across tbe moutb of tbe bay. The bar probably began its formation as a spit anchored to tbe nortbern bedrock headland, and tbrough continued accretion of sand tbe bar grew soutbward, eventually isolating part of tbe bay from Lake Michigan. Strong nortbeasterly winds offtbe lake tben reworked tbe sand, piling it into tbe dune complex tbat now separates Europe Lake from Lake Michigan (Fig. 8).

The bar apparently began to form during tbe Nipissing phase of lake history at about 5,000 B.P:, or shortly tbereafter. A well-defined and continuous AIgonquin shoreline is present a short distance west of Europe Lake, and botb tb,e character of tbe dunes imd tbeir general elevation are typical or" tbe Nipissing and' post-Nipissing shoreline tbroughout tbe Door Peninsula and fartber soutb adjacent to tbe modern shoreline of Lake Michigan.

Three 2-m cores of lake sediment were obtained from tbe bottom of Europe Lake in February, 1992 (Fig. 9). Peat from below tbe lowest lake sediment in one of tbe cores was radiocarbon dated at 6,610 ± 150 yr B.P. (Beta-563 10). Detrital wood from tbe base of a second core has not yet been dated. Studies of tbe sedimentology, palynology, and tbe snail and ostrocode faunas are in progress and will be reported upon. Please see contributed papers by Mode and Maher, Miller, and Smitb elsewhere in tbis guidebook.

End of road log for Day 1. Return to Sturgeon Bay via Europe Bay Road and Wisconsin Highways 42 and 57 or, if time permits, by more scenic alternalive routes.

137

EUROPE LAKE

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138

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DAY2 Sunday, May 23

(All distances have not been map corrected. Depending on the setting of the odometer in your vehic1e, mileages may be slightly different from those recorded here.)

0.0 0.0 Best Western Maritime Inn at intersection ofEgg Harbar Road (Business 42-57) and N 14th Avenue. Head south on 14th Avenue.

0.9 0.9 Stop signo Turn left (E) onto Michigan Street.

1.6 0.7 Stop signo Turn right (S) onto Wisconsin Highway 42-57.

2.6 1.0 Cross Sturgeon Bay on the Bay View Bridge. Sturgeon Bay occupies a linear bedrock valley (Martin, 1916; Sherrill, 1978) similar to those farther north (e.g., the Porte des Morts Passage or Death's Door between the tip ofthe peninsula and Washington Island). The lower or eastern end of the ship canal between Lake Michigan and Green Bay does not, however, coincide with the axis ofthe valley, according to Sherrill's bedrock topography map (Sherrill, 1978, PI. 1), but follows a shorter route between the city and the lake.

The ship canal is about 17.7 km (11 miles) long and from 5.2 to 6.4 m (17 to 21 feet) deep. Dredging for the canal began in 1872; the canal was opened for commerce in 1881 and full navigation began in 1882. Completion of the canal shortened the water route from Green Bay to Milwaukee andChicago by about 160 km (100 miles), as well as avoiding the dangerous Porte des Morts Passage at the north end of the peninsula. During'the peak years of the timber industry in the 1880s and 1890s the canal annually handled 7,000 vessels carrying a cargo of 600,000,000 board feet of lumber. The City of Sturgeon Bay rapidly became an important port city and eventually attracted a large maritime industry.

4.8 2.2 Stop light. Ahead and to the south is a small drumlin field consisting of about a dozen drumlins composed of Liberty Grove till (Fig. 10). Sorne carry a thin blanket of red c1ayey till currently assigned to the Glenmore Member of the Kewaunee Formation. The drumlins trend S. 25 o E. To the best of our knowledge, these features were first noted by F. T. Thwaites; an air photo of the drumlins appears in Thwaites and Bertrand's (1957) paper on the Pleistocene geology of the Door Peninsula.

The matrix of the till in these drumlins appears to be much more sandy than is typical for the Liberty Grave. Laboratory analyses of only two samples are available to confirm this observation, however; both samples contain 70% or more sand and average 71 % sand,23% silt, and 6% c1ay. No explanation is offered for the significantly higher sand contento

Turn right (N) at stop light onto Duluth Avenue (County Trunk Highway C).

5.8 1.0 Stop signo Turn left (W) onto W Elm, following County C and continue west past Cherryland Airport on the right.

8.8 3.0 Turn ri~ht (N) onto County Trunk Highway M (Idlewild Road) and stop about 150 feet north of the intersection.

139

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STOP 9, Stream swallet and spring complexo This stop consists of two parts and will be handled by Ron Stieglitz and BiII Schuster, who contributed the description ofthe stop. (See also contributed paper by Stieglitz and Schuster elsewhere in this guidebook.) The area was described by Wiersma and others (1986) and currently serves as a field-study area for several master's theses in progress at the University of Wisconsin-Green Bay.

STOP 9a, Sinkhole/swallet. SWl/4 SWl/4 seco 3, T. 27 N., R. 25 E.; Sturgeon Bay West 7.5-minute quadrangle.

This sinkhole intercepts the flow of a tributary to Larson Creek (formerly called Sawyer Creek). The abandoned channel appears to have extended northward to the spring and over the escarpment just to the southwest of the main channel. That channel is found across the field in the trees to the northeast. The headwater area of the watershed consists of relatively low-relief farrnland and wetlands to the south and southwest. Surface flow in the channels is intermittent and occurs primarily during and shortly after the snow melt in the spring of the year. Several swallets located in the main channel intercept water until the shallow aquifer is full and surface flow occurs.

Field mapping has located a variety of karst features ranging from small-scale surface karren to sinkholes up to several meters in diarneter. The dominant set of bedrock joints, sorne of which have been widened by solution, strike N 73 ° E. A more variable set strikes from N 40° W to N 50° W. Probes in the wetlands indicate that 1 t03 m of organic soils are separated from the bedrock by thin clays of probable glacial origino

Continue ahead (N) on County M.

9.8 1.0 Turn left (W) onto Sand Bay Road.

9.9 0.1 STOP 9b, Spring complex on property ofRobert Sperber. NEl/4 seco 4, T. 27 N., R. 25 E.; Sturgeon Bay West 7.5-minute quadrangle.

Below the escarpment water discharges from a number of places along the rock face and forrns a permanent strearn that flows approximately 2.5 km (1.5 miles) 10 Green Bay. The volume and level of discharge vary seasonally and with available recharge. More and higher outflow points are active in the spring of the year. Tracer studies indicate that both the sinkhole at Stop 9a and the main swallet in the strearn channel are directly connected to the spring complexo A tracer injected into a swallet in the main channel during a period of high flow reached the spring about 1 km (0.6 mile) away in less than two hours. Tracer placed in the sinkhole at Stop 9a traveled the nearly 2 km (1.2 miles) in just over two hours.

The spring discharge, swallet inflow, and both surface and shallow subsurface water in the wetlands have been monitored for a number of water-quality pararneters. The results indicate that the turbidity and the concentrations of nitrate-nitrogen, arnrnonia-nitrogen, and total phosphorous of the discharge at the spring complex are affected by direct mnin to the swallets, inflltration through the soils, and retention and/or resuspension ofparticulates in the karst conduits.

Turn around and head east on Sand Bay Road.

141

10.0 0.1 Stop signo Turn left (N) onto County M. Note quarry to the northeast in the Byron and Hendrieks Formations of the Burnt Bluff Group (Iower middle Silurian) at erest of the Niagara Esearpment.

10.2 0.2 Note broad wave-eut terrace of the Nipissing phase ahead and to the left.

10.5 0.3 Cross the Nipissing shoreline at approximately 184 m (605 feet).

11.0 0.5 Turn right (E) onto Hainesville Road. Note prominent Nipissing shoreline trending NE-SW cuton reddish-brown clay-rich till assigned to the Glenrnore Member of the Kewaunee Formation.

11.4 0.4 Leave the Nipissing terrace and recross the Nipissing shoreline. Door County sanitary landfill on the right, Hainesville Cemetery on the left, Lost Creek golf eourse farther to the north. Note low road cuts in red till all along this road.

12.0 0.6 Stop signo Turn right (S) onto Gitchee Gumee Road.

12.5 0.5 Turn left (E) onto Park Drive.

13.0 0.5 Turn right (S), following Park Drive.

13.4 0.4 Entrance to Potawatomi State Park on left. ·Continue ahead past Cherryland Airport on left.

14.5 1.1 Stop signo Turn left (E) onto County Trunk C.

16.0 1.5 Turn right (S) onto Duluth Avenue (County C).

17.0 1.0 Stop Iight. Turn left (E) onto Wisconsin Highway 42-57.

18.7 1.7 Turn right (S) onto County Trunk U (Claybanks Road).

,

18.9 0.2 Bear left at Y -junction with Division Road and parallel a prominent shoreline on the right for the next mile and a half. This shoreline, at about 189 m (620 feet), was interpreted by Goldthwait (1907, p. 71; PI. 23, fig. 1) to be the AIgonquin shore. It is elearly cut on red clayey till of the Kewaunee Formation, which is eurrently interpreted to be the post-Two Creeks Glenrnore Member deposited by the Green Bay Lobe.

19.2 0.3 Pit on right exposes up to 6 m (20 feet) of red till overlying 2.8 m (9 feet) of sand with sorne gravel layers, interpreted to be mostly lacustrine and beaeh deposits. Samples of till from this pit and nearby exposures have virtually the same grain-size distribution and clay-mineral composition (27% expandables, 58% illite, 15% kaolinite plus ehlorite) as sampleS from exposures several miles to the northwest in the area of Stop 9.

Several years ago Dave Mickelson observed shallow grooves oriented NW -SE at the base of the till, which is consistent with the interpretation that the unit was deposited by the Green· Bay Lobe. This interpretation is well supported by two till-fabrie analyses (Fig. 11) made at this exposure by Ardith Hansel and myself in 1991; one shows a distinct, the other a strong NW-SE orientation (azimuths of 320 and 323 degrees, plunge values of 10 degrees).

142

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S, 320° 10° 0.84 S, 323° 10· 0.65 . S, 51° 8° 0.14 S, 55° . 7° 0.30

S, 178° 77° 0.02 S, 180° 78° 0.04

Figure 11. Fabrics on prolate pebbles io the red till (Gleomore) exposed io pil 00 Claybanks Road south of Slurgeon Bay. (Courtesy of Ardilh Hansel.)

20.4 1.2 Bear right at Y-intersectioo, continuing south on County Trunk U. Cross the AIgonquin shoreline and rise onlo the upland. Note exposure of red till on the right.

25.2 4.8 Junction with County Trunk 00 from the right. Continue ahead on County U.

26.2 1.0 Bear left at intersection with Midway Road, descend to wave-cut terrace at mouth of Schuyler Creek, and then rise about 12 m (40 feet) back onto the upland.

27.4 1.2 Junction with County Trunk J from the right. Continue ahead on County U.

27.8 0.4 Turn left into upper parking lot at LaSalle County Park.

143

27.9 0.1 STOP 10, Rohert LaSalle County Park. SWl/4 SEl/4 seco 29 and NWl/4 NEl/4 seco 32, T. 26 N., R. 26 E.; AIgoma NE 7.5-minute quadrangle. Rest facilities are available.

Tbe inscription on tbe monument at tbe top of tbe stairway reads as follows:

rhe Most I/lustrious Son of Normandy

Storm driven and without food, in October 1679, Roben LaSaUe with founeen men, on a voyage to explore the interior of Amerlea, landed at this place. Expecting hostile Indians he erected a barricade, but instead of war they brought provisions and saved his lije.

Descend stairs to lower level of tbe park and walk across bedrock-defended terrace to tbe lakeshore. In places where tbis surface is hest preserved, tbe elevation at tbe upper edge of tbe tread (near tbe base oftbe stairs) is 183-184 m (600-605 feet), suggesting tbat tbe terrace is Nipissing. At tbe lakeshore, however, tbe surface is only a few feet aboye tbe modern water plane, suggesting tbat it is an AIgoma terrace. Tbe tread was probably cut during Nipissing time and subsequently stripped during tbe AIgoma phase. Tbe prominent riser behind tbe terrace here and immediately to tbe nortb was described by Goldtbwait (1907, p. 69), who stated tbat "nowhere along tbe eastern Wisconsin shore is tbere a bluff of more remarkable strengtb." It seems reasonable to conclude tbat tbe blúff was cut initially during tbe Algonquin stage, and tbe AIgonquin tread was stripped during at least two subsequent lake phases (Nipissing and AIgoma).

Walk soutb along tbe Lake Michigan shoreline several hundred .yards to a long 21-24 m (70-80 foot) bluff tbat exposes red clayey diamicton of tbe Kewaunee Formation. AIl evidence of former shorelines here has been erased by shoreline recession associated witb tbe modernlake phase (i.e., post-Algoma).

Several years ago two red tm units separated by 1-3 m (3-10 feet) of sand, witb an average tbickness of 2.5 m (8 feet), were observed near tbe nortb end of tbis exposure. The upper till was about 2.5 m tbick; tbe tbickness of tbe lower tm coulq not be determined. The same stratigraphy has not been seen on subsequent visits, however.

At tbe time when tbe two units were observed, tbe upper tm was tentatively correlated as tbe Glenmore Member (Green Bay Lobe) on tbe basis of surficial distribution and locallandform orientation, and tbe lower tm was considered to be tbe Two Rivers Member (Lake Michigan Lobe). Thus, botb units were considered to be post-Two Creeks in age. Tbe same conclusions were independently infened by J anet Heiny (unpublished manuscript), who identified Glenmore tm aboye Two Rivers 1m after studying a Lake Michigan bluff cut on tbe nortb side of tbe Kewaunee River valley. Soutb of Kewaunee, however, tbe Glenmore tm appears to be below tbe Two Rivers till (Acomb and otbers, 1982).

Herb Glass, to whom 1 am indebted for all tbe clay-mineral analyses cited here, has suggested tbat tbe red tills can be differentiated on tbe basis of illite percentages. However, tbere appears to be no more consistency in illite content tban in tbe percentages of tbe otber clay-mineral groups.

144

The clay-mineral composition of fue upper till at LaSalle Park is 25% expandables, 59% illite, and 16% kaolinite plus chlorite -- virtually identical to samples from farther north. A sampleof Two Rivers tm from its type locality is similar in composition (28/60/12) to fue upper till here, but a second sample from Two Rivers is quite dissimilar (38/48/14). The lower percentage of expandable mineral s in fue lower tm (17% expandables, 62 % illite, 21 % kaolinite plus· chlorite) may or may not be significant. This composition is virtually identical wifu fuat of a sample of pre-Two Creeks till from below fue forest bed at Two Creeks (17/61/22), but a second sample from below fue Two Creeks forest bed has a dissimilar composition (24/53/23). The results of clay-mineral analyses fróm shoreline and inland exposures soufu of here are equally confusing. Twenty-one samples of Glenmore till from fue Denmark Moraine and Glenmore ground moraine farther to fue west, however, are much more consistent and show a significantly higherpercentage of expandable mineral s, averaging 34% expandables, 50% illite, and 16% kaolinite plus chlorite.

A single fabric analysis of 30 prolate pebbles from fue tm here at LaSalle Park shows only a weak fabric (azimufu of 268 degrees, plunge 16 degrees). More analyses are c1early needed.

Thus, many critical questions regarding fuis exposure remain unanswered. What unit or units are present here? Is only one tm present? Or is more fuan one tm present? If only one till is present, was it deposited by fue Lake Michigan Lobe or by fue Green Bay Lobe? In eifuer case, is fuat till pre-Two Creeks or post-Two Creeks in age? If two unÍts are present, are

. they bofu Lake Michigan Lobe tills, are they bofu Green Bay Lobe tills, or isthere one of each? Are fuey bofu pre-Two Creeks in age, are fuey bofu post-Two Creeks, or is one unit pre-Two Creeks and the other post-Two Creeks? Ifboth units are post-Two Creeks and fue upper one is indeed the Glenrnore,. why did the Green Bay Lobe reach fue Michigan shoreline prior to the transgression 'of fue Lake Michigan Lobe? .

Continue southwestward on County Trunk U.

29.2 1.3 Leave Door County, enter Kewaunee County. Continue soufu and west on County U.

31.2 2.0 Stop signo Turn left (S) onto County Trunk S.

32.4 1.2 Note prominent riser and terrace tread on left side of road. This surface most certainly was cut during the Nipissing phase.

33,9 1.5 Enter village of AIgoma. AIgoma is fue home ofthe von Steil Winery, which is well known for its production of Door County cherry wines.

34.8 0.9 Cross the Ahnapee River and follow County S south -- do nQ! turn right on S west after crossing fue river. The Ahnapee River valley is the lowest and last outlet for overflow waters of glacial Lake Oshkosh in the Fox River lowland prior to fue retreat of ice from fue Sturgeon Bay lowland (Wielert, 1980).

35,3 0.5 Stop sign at junction with Wisconsin Highway 42. Turn half left onto 42.

35.4 0.1 Junction wifu Wisconsin Highway 54. Continue ahead on 42 through AIgoma toward Kewaunee.

145

36.7 1.3 Note terrace below highway level on left side of road. Although the elevation ofthe terrace suggests that it was occupied during the AIgoma phase, it was probably formed during the Nipissing phase and then stripped during the AIgoma, as at LaSalle Park.

38.0 1.3 Wayside park on left. Nipissing or early post-Nipissing sand dune on right side of highway near south end of the park.

40.2 2.2 Enter Alaska.

40.6 0.4 East Alaska Lake to the right and West Alaska Lake to the southwest (not visible from highway) occupy large kettles near the south end of a moraine of undetermined signifícance. Possibly it is the end moraine of the late Woodfordian Lake Michigan Lobe which farther to the southwest forms a major component of the Kettle Interlobate Moraine.

43.5 2.9 Crossroads of Rostok.

45.1 1.6 Enter the City of Kewaul,lee and descend into the Kewaunee River valley.

45.6 0.5 Cross the Kewaunee River valley (Fig. 12). This impressive valley served as an important oudet for glacial Lake Oshkosh at a higher and earlier phase than the Ahnapee level (Wielert, 1980) .. Terraces and other features a10ng the valley indicate a complex history that warrants investigation. Continue south on Highway 42 through the city of Kewaunee and return to the upland.

47.1 1.5 Across the fíeld to the left (E) on the lakeshore is a 29-m (95-foot) bluff composed entirely of drift (no bedrock). A Two Creeks-age organic horizon, with radiocarbon dates of 11,700 ± 110 (ISGS-I061) and 11,650 ± 170 (ISGS-1234) yr B.P., occurs near the top ofthe bhiff under red till. See reprint ofpaper by Garry and others (1990) from GSA Special Paper 251 elsewhere in this guidebook. This exposure is the site of a memorable international fíeld-trip experience several years ago (see Dave Mickelson for details).

55.5 8.4 Kewaunee Nuclear Power Plant, operated by Wisconsin Public Service Corporation, on left.

56.6 1.1 Manitowoc County lineo Junction with County Trunk BB on the right, GIBS restaurant on the left. Turn left into parking area irnmediately south of GIBS (excellent meaIs!)

STOP 11, Two Creeks Forest Bed Site. NEl/4 NEl/4 seco 2, T. 21 N., R. 24 E.; Two Creeks 7.5-minute quadrangle.

The Two Creeks Forest Bed (Fig. 13) was described fírst by James Walter Goldthwait (1907) and more recently by Thwaites and Bertrand (1957) and in several papers by Bob Black. Please refer to reprint of paper by Black (1970) elsewhere in this guidebook; Black's paper was prepared for the Annual Meeting of the Geological Society of America in Milwaukee, but the site has not been visited on a Friends of the Pleistocene. field trip since 1953. Although the full stratigraphic section is now only partially and poorly exposed, it seems appropriate to examine the site again 40 years later,

146

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Figure 13. Diagrarnmatic cross section along the Lake Michigan shore at the Two Creeks site. (prom Black, 1970, fig. 7; modified from Thwaites and Bertrand; 1957, fig. 12.)

The Two Creeks Forest Bed, with an average radiocarbon age of 11,850 yr B.P. (Broecker and Farrand, 1963), remains a significant time-stratigraphic horizon for late Wisconsinan events in the Lake Michigan basin. The stratigraphy at the site not only records the growth of a spruce forest, but it also attests to a series of events that include two advances and retreats of the Lake Michigan Lobe and three lake phases. The forest bed clearly defines an interstadial interval (Twocrookan Interstade) that separates the Woodfordian Substage from the Greatlakean (formerly Valderan) Substage.

This site (Fig. 14), as one of the units in Wisconsin's Ice Age National Scientific Reserve, is under the jurisdiction of the National Park Service. As such, digging and sample collecting are iIlegal activities.

The following description of the site is modified from Black's description in the road log from the 1970 GSA guidebook. When it is completely exposed, the section (Fig. 15) shows a gray to red clayey till at lake level that grades upward into massive lake sediments, which ¡i¡ turo grade upward into rhythmically bedded clays and silts overlain by beach sand and grave!. The Two'Crooks buried soil was formed on these beach sediments'and is an immature Podsol (Udorthent). The forest was drowned by rising lake waters represented by lacustrine sand deposited irnmediately prior to and during the last readvance of the Lake Michigan Lobe (the Two Rivers advance). The glacier contorted and eroded the soH in many places and deposited several foot of till aboye the lake sediments. The till is overlain by additional lacustrine sediments, which extend to the top of the bluff.

The lower till unit was called Cary till by Thwaites and Bertrand (1957); it is currently interpreted as either the Valders till (Evenson, 1973) or the Haven till (Acomb and others, 1982). The upper till is the Two Rivers till (Evenson, 1973). The lowermost lake sediments represent either the Glenwood TI phase or the Calumet 1 phase of Glacial Lake Chicago; very possibly they correlate with the lacustrine sands below the Two Rivers till at its type locality 17.7 km (11 miles) to the south (Evenson, 1973; Schneider, 1990b). The lake sediments aboye the forest bed a1most certainly represent the Calumet phase of Lake Chicago and those at the top of the section were probably deposited during the late Calumet-Kirkfield (main Algonquin) phase.

Continue south on Wisconsin Highway 42.

148

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• 18 Depth in feet to Two Creeks soil

o '33 Depth in feet of dril I hole without Two Creeks soil

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Figure 14. Map of the Two Creeks area showing loeations of drill holes. Topography derived from U.S. Geologieal Survey Kewaunee and Manitowoe Quadrangles. (From Black, 1970, fig. 5.)

149

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Figure 15. Diagrammatic section of the stratigraphy at the Two Creeks si te. (From Black, 1970, fig. 6.)

150

58.6 2.0 Crossroads of Two Creeks.

59.6 1.0 Point Beach Nuclear Power Plant, owned and operated by Wisconsin Electric Power Company, on lakeshore to the east. This facility has been cited regularly as one ofthe most efficient and reliable nuclear plants in the nation. When the plant was under construction about 25 years ago, the Two Creeks Forest Bed, with large trees in growth position, was encountered by earth-moving equipment. This event led directiy to the purchase of the classic Two Creeks site (Stop 11) by The Nature Conservancy, primarily through the efforts of Bob Black.

62.8 3.2 Turn left (E) onto County Trunk V (formerly Wisconsin Highway 177).

64.5 1.7 Cross the Nipissing shoreline, then the northern end of a former lagoon now occupjed by Molash swamp (Fig. 16), and then an early post-Nipissing baymouth bar.

65.4 0.9 Turn right (S) and follow County Trunk O.

67.1 1.7 Entrance road to Point Beach State Forest. Turn left and proceed across a series of beautiful beach-dune ridges and intervening swales.

67.4 0.3 Contact station, Point Beach State Forest. Turn left just beyond contact station and follow park road northward to stop sign and then eastward to the main parking area and shelter-concession-IÍature center building.

68.2 0.8 STOP 12, Point Beach State Forest. NWl/4 NEl/4 seco 9, T. 20 N., R. 25 E.; Two Rivers 7.5-minute quadrangle.

This stop will be handled by Eric Dott, who contributed the following description of the stop and a contributed paper elsewhere in this g\lidebook ..

Two beach-ridge complexes occur at Two Rivers, one north and one south of the city. At this stop we will visit the northern ridge complex, which is included in Point Beach State Forest. The visitor's center is near the middle of this northern complex, an arcuate-shaped group of low (0.5 to 8 m high) north-south trending ridges. We will frrst observe the Lake Michigan shoreline and then follow a short nature trail to the west to observe sorne beach ridges and intervening peat-filled swales. .

The Point Beach complex is the larger of the two ridge complexes and contains as many as 30 ridges. The ridges occur in groups of truncated subparallel ridges. The southern Woodland Dunes complex also exhibits this pattern of groups of truncated ridges, which represent realignments of the shoreline due to changes in sediment influx and/or changes in lake leve!. The two ridge complexes have undergone up to eight such realignments during their development.

Progradation ofthe shoreline has occurred at Two Rivers primarily over the last 3,000 years, as indicated by radiocarbon dates on peat and detrital wood. Evidence of lake transgression prior to the progradational development of the ridges is indicated by a sharp wave-cut till scarp that occurs along the western border of Point Beach State Forest. This abandoned scarp is located inland and aboye the ridge complex. It was crossed on County Trunk V between Highway 42 and the lake.

151

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Radiocarbon dates for basal peat samples collected from selected swales in tbe ridge complex decrease in age toward tbe lakeshore. Basal peat from tbe prominent swampy swale tbat parallels County Trunk O was dated at 3,150 ± 110 yr B.P. Basal peat samples from tbe two strong nortb-soutb water-filled swales tbat bound a sharp beach ridge crossed on tbe entrance road gave distinctly younger dates: peat from tbe large western swale (Clam Swale) was dated at 1;540 ± 70 yr B.P., and peat from tbe eastern swale (Snake Swale) was dated at 1,390 ± 130 yr B.P. (See paper elsewhere in tbis guidebook for radiocarbon dates from tbe ridge complexes.)

The beach ridges, like tbose along tbe nature trail west of tbe visitar center, contain beach sediments capped by dune deposits tbat range from 0.5 to 2 m tbick. Most of tbe ridges are separated by low wet swales, which in sorne cases contain peat deposits up to 1.5 m tbick. Back-beach facies witb laminated sands overlie coarse-grained, laminated, and cross-laminated foreshore sediments tbat form tbe cores of tbe ridges and extend beneatb tbe swales. The foreshore sediments are underlain by rippled cross-laminated or subparallel laminated sands tbat represent upper shoreface deposits.

End of road lag. Rave a safe trip home.

153

REFERENCES CITED (Road Log Only)

Acomb, L. J., Mickelson, D. M., and Evenson, E. B., 1982, TiII stratigraphy and late glacial events in the Lake. Michigan Lobe of eastern Wisconsin: Geological Society of America Bulletin, v. 93, p.289-296.

B1ack, R. F., 1970, Glacial geology ofthe Two Creeks Forest Bed, Valderan type locality, and northern Kettle Moraine State Forest: Wisconsin Geological and Natural History Survey Information Circular No. 13, 40 p.

Broeker, W. S., and Farrand, W. R., 1963, Radiocarbon age ofthe Two Creeks Forest Bed, Wisconsin: Geological Society of America Bulletin, v. 74, p. 795-802.

Chamberlin, T. C., 1877, Geology of eastern Wisconsin, in Geology of Wisconsin, v. 2, p. 91-405. Evenson, E. B., 1973, Late Pleistocene shorelinesand stratigraphic relations in the Lake Michigan basin:

Geological Society of America Bulletin, v. 84, p. 2281-2298. Garry, C. E., Baker, R. W., Schwert, D. P., and Schneider, A. F., 1990, Environmental analysis of a

Twocreekan-aged beetle (Coleoptera) assemblage from Kewaunee, Wisconsin, in Schneider, A. F., and Fraser, G. S., eds., Late Quaternary history of the Lake Michigan basin: Geological Society of America Special Paper 251, p. 57-65.

Goldthwait, J. W., 1907, The abandoned shore Iines of eastern Wisconsin: Wisconsin Geological and Natural History Survey Bulletin 17, 134 p.

Heiny, J. S., unpub., Glacigenic sediment facies associations along the western shore of Lake Michigan near Kewaunee, Wisconsin.

Kowalke, O. L., 1947, Highest abandoned beach ridges in northern Door County, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Transactions (for 1946), v. 38, p. 293-298.

__ , 1952, Location of drumlins in the town of Liberty Grove, Door County, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Transactions, v. 41, p. 15-16. .

Krumbein, W.C., and Griffith, J.S., 1938, Beach environment in Little Sister Bay, Wisconsin: . Geological Society of America Bulletin, v. 49, p. 629-652. .

Leverett, F., and Taylor, F. B., 1915, The Pleistocene of Indiana and Michigan and the history of the Great Lakes: U.S. Geological Survey Monograph 53, 529 p ..

. Martin, Lawrence, 1916, The physical geography of Wisconsin: Wisconsin Geological and Natural History Survey Bulletin 36, 608 p. (Second edition published in 1932, third edition in 1965.)

Mickelson, D. M., Clayton, L., Baker, R. W., Mode, W. N., and Schneiqer, A. F., 1984, Pleistocene stratigraphic units of Wisconsin: Wisconsin Geological and Natural History Survey Miscellaneous Paper 84-1, 97 p.

Mickelson, D. M., and Syverson, K. M., in press, Pleistocene geology of Ozaukee and Washington Counties, Wisconsin: Wisconsin Geological and Natural History Survey Information Circular.

Schneider, A. F., 1981, Late Wisconsinan glaciation of Door County, Wisconsin: Geological Society of America Abstracts with Programs, v. 13, p. 316.

__ ' 1988, Late Quaternary shorelines of the Door Peninsula, Wisconsin: American Quaternary Association Program and Abstracts, 10th Biennial Meeting, University of Massachusetts, Arnherst, p. 148.

__ ' 1989, Geomorphology and Quaternary geology of Wisconsin's Door Peninsula, in Palmquist, J. C., ed., Wisconsin's Door Peninsula; A Natural History: Perin Press, Appleton, Wisconsin, p. 32-48.

__ ' 1990a, Door County's glacial heritage; A foundation for the future, in Hershbell, K. E., ed., Door County and the Niagara Escarpment; Foundations for the future: Wisconsin Academy of Sciences, Arts and Letters Conference Proceedings, October 1989, p. 15-35.

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__ ' 1990b, Radiocarbon confirmation of Ihe Greatlakean age of Ihe type Two Rivers till of eastern Wisconsin, in Schneider, A. F., and Fraser, G. S., eds., Late Quaternary history of Ihe Lake Michigan basin: Geological Society of America Special Paper 251, p. 51-55.

Sherrill, M. G., 1978, Geology and ground water in Door County, Wisconsin, wilh emphasis on contamination potential in Ihe Silurian dolomite: U. S. Geological Survey Water-Supply Paper 2047,38 p.

Thwaites, F. T., and Bertrand, Kennelh, 1957, Pleistocene geology of Ihe Door Peninsula, Wisconsin: Geological Society of America Bulletin, v. 68, p. 831-880.

Wielert, J. S., 1980, The late Wisconsinan glacial lakes of Ihe Fox River watershed, Wisconsin: Wisconsin Academy of Sciences, Arts and Letters Transactions, v. 68, p. 188-201.

Wiersma, 1. H., Stieglitz, R. D., Cecil, D. L., and Metzler, G. M., 1986, Characterization of Ihe shallow ground-water system in an area of Ihin soils and sinkholes (Door County, Wisconsin): Environmental Geology and Water Science, v. 8, no. 1/2, p. 99-104 .

155

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LITHOSTRATIGRAPHIC

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