CENOZOIC Quaternary

Q a Alluvium and colluvium Q t Gravel, pediment, and fan deposits Q g Glacial deposits Q ls Landslide deposits Q s Dune sand and loess Q u Surficial deposits, undifferentiated

Quaternary and Tertiary Q Tg Terrace gravel

Tertiary Tmu U pper Miocene rock s Tml Low er Miocene rock s Tmo Low er Miocene and upper Oligocene rock s or rock s equivalent to upper

and low er Miocene rock s and W hite R iver Formation Tw b W agon Bed Formation Tw r W hite R iver Formation Tw ru U pper conglomerate member Tie Intrusive and extrusive igneous rock s–incorporates masses of Mississippian through Cambrian formations Tw W asatch Formation

Tw mo Moncrief Member Tw k Kingsbury Conglomerate Member Tfu Fort U nion Formation Tftr Tongue R iver Member Tftl Tongue R iver and Lebo Members Tfl Lebo Member Tflt Lebo and Tullock Members Tft Tullock Member

MESOZOIC Cretaceous

Kl Lance Formation Klm Lance Formation, Fox Hills Sandstone, Meeteetse Formation, and

Bearpaw and Lew is Shales Kfh Fox Hills Sandstone Kfl Fox Hills Sandstone and Lew is Shale Kfb Fox Hills Sandstone and Bearpaw Shale Kmv Mesaverde Formation Kc Cody Shale Kp P ierre Shale Kn Niobrara Formation Knc Niobrara Formation and Carlile Shale Kcl Carlile Shale Kgb Greenhorn Formation and Belle Fourche Shale

Kgbm Greenhorn Formation, and Belle Fourche and Mow ry Shales Kf Frontier Formation Kft Frontier Formation, and Mow ry and Thermopolis Shales Kmr Mow ry Shale Kmt Mow ry and Thermopolis Shales Kns New castle Sandstone and Sk ull Creek Shale Kle Lew is Shale

Cretaceous and Jurassic KJ Cloverly Formation (Hartville U plift) or Inyan Kara Group (Black Hills)

and Morrison Formation KJs Cloverly, Morrison, and Sundance Formations KJg Cloverly, Morrison, Sundance, and Gypsum Spring Formations

Jurassic Js Sundance Formation Jsg Sundance and Gypsum Spring Formations

Triassic ^c Chugw ater Formation ^cd Chugw ater and Dinw oody Formations MESOZOIC AND PALEOZOIC ^P cg Chugw ater and Goose Egg Formations ^P g Goose Egg Formation ^P s Spearfish Formation

MzP z Mesozoic and P aleozoic rock s, undifferentiated

PALEOZOIC Permian

P p P hosphoria Formation and related rock s P mo Minnek ahta Limestone and Opeche Shale

Permian and Pennsylvanian P *c Casper Formation P *h Hartville Formation–low ermost unit may be Late Mississippian P *m Minnelusa Formation

Permian, Pennsylvanian, and Mississippian P M Tensleep Sandstone and Amsden Formation P *M Casper Formation and Madison Limestone

Mississippian Mm Madison Limestone or Group–includes w edge edge of Bighorn Dolomite

in Tps. 43 and 44 N., R gs. 85 and 86 W Mississippian and Devonian

MD Madison Limestone and Darby Formation MDe P ahasapa and Englew ood Limestones MDg Guernsey Formation–locally includes dolomite and sandstone of

Devonian and Cambrian(?) age Mississippian and Ordovician

MO Madison Limestone and Bighorn Dolomite–east side of Bighorn Mountains Mississippian, Devonian, Ordovician, and Cambrian

P zr Minnek ahta Limestone, Opeche Shale, Minnelusa Formation, P ahasapa and Englew ood Limestones, W hitew ood Dolomite, and W innipeg and Deadw ood Formations–various combinations

Ordovician Ob Bighorn Dolomite

Ordovician and Cambrian O_ Bighorn Dolomite, Gallatin Limestone, Gros V entre Formation, and

Flathead Sandstone Cambrian

_u Gallatin Limestone, Gros V entre Formation and equivalents, and Flathead Sandstone

PRECAMBRIAN =u P recambrian rock s, undifferentiated

Ob

O_

_u

=u

104°0'W

104°30'W

104°30'W

105°0'W

105°0'W

105°30'W

105°30'W

106°0'W

106°0'W

106°30'W

106°30'W

107°0'W

107°0'W

107°30'W

107°30'W

45°0'N

45°0'N

44°30'N

44°30'N

44°0'N

44°0'N

43°30'N

43°30'N

43°0'N

43°0'N

42°30'N

42°30'N

Scale 1:350,000

WYOMING STATE GEOLOGICAL SURVEYThomas A. Drean

Director and State GeologistLaramie, Wyoming

Map Projection: Lambert Conformal Conic False Easting: 500000, False Northing: 200000Central Meridian: -107.5 degrees WestStandard Parallel 1: 41 degrees NorthStandard Parallel 2: 45 degrees NorthLatitude of Origin: 41 degrees NorthLinear Unit: MeterHorizontal Datum: North American Datum of 1983 (NAD 83)Ellipsoid: Geodetic Reference System 80

GEOLOGIC MAP OF THE POWDER RIVER BASIN, WYOMING

DISCLAIMERS U sers of these maps are cautioned against using the data at scales different from those at w hich the maps w ere compiled. U sing this data at a larger scale w ill not provide greater accuracy and is, in fact, a misuse of the data. The W yoming State Geological Survey (W SGS) and the State of W yoming mak e no representation or w arranty, expressed or implied, regarding the use, accuracy, or completeness of the data presented herein, or of a map printed from these data. The act of distribution shall not constitute such a w arranty. The W SGS does not guarantee the digital data or any map printed from the data to be free of errors or inaccuracies. The W SGS and the State of W yoming disclaim any responsibility or liability for interpretations made from these digital data or from any map printed from these digital data, and for any decisions based on the digital data or printed maps. The W SGS and the State of W yoming retain and do not w aive sovereign immunity. The use of or reference to trademark s, trade names, or other product or company names in this publication is for descriptive or informational purposes only, or is pursuant to licensing agreements betw een the W SGS or State of W yoming and softw are or hardw are developers/vendors, and does not imply endorsement of those products by the W SGS or the State of W yoming.

NOTICE TO USERS OF INFORMATION FROM THE WYOMING STATE GEOLOGICAL SURVEY

The W SGS encourages the fair use of its material. W e request that credit be expressly given to the “W yoming State Geological Survey” w hen citing information from this publication. P lease contact the W SGS at 307-766-2286, ext. 224, or by email at w sgs.sales@w yo.gov if you have questions about citing materials, preparing ack now ledgments, or extensive use of this material. W e appreciate your cooperation. Individuals w ith disabilities w ho require an alternative form of this publication should contact the W SGS. For the TTY relay operator call 1-800-877-9975. For more information about the W SGS or to order publications and maps, go to w w w .w sgs.uw yo.edu, call 307-766-2286, ext. 224, or email w sgs.sales@w yo.gov.

EXPLANATION

Geology - Interpreting the past - providing for the future

GEOLOGIC UNITS(Geology enlarged from 1:500,000 scale to improve readability)

0 10 20 30 40 50Miles

0 20 40 60 80Kilometers

Qa

Qt

Qg

Qls

Qs

Qu

QTg

Tmu

Tml

Tmo

Twb

Twr

Twru

Tie

Kl

Klm

Kfh

Kfl

Kfb

Kp

Kmv

Kc

Knc

Kcl

Kgb

Kf

Kft

Kgbm

Kmr

Kmt

Kns

KJ

KJg

KJs

Kn

Js

Jsg

^c

^cd

^Ps

^Pcg

^Pg

MzPz

Pp

Pmo

P*c

Pzr

P*h

P*m

P*M

PM

Mm

MD

MDe

MDg

MO

MAP SYMBOLS

DATA REFERENCE Love, J.D., and Christiansen, A.C., comps., 1985, Geologic map of W yoming: U .S. Geological Survey, 3 sheets, scale

1:500,000.

BASE MAP REFERENCES Bureau of Indian Affairs, 2005, Boundaries— Indian Lands, R aw Data R elease, December, 2005: National Atlas of the

U nited States, at http://nationalatlas.gov/. Bureau of Land Management, 2011, Cadastral National Spatial Data Infrastructure (CadNSDI) P ublic Land Survey System

(P LSS) for W yoming, at http://w w w .geocommunicator.gov/geocomm/ lsis_home/home /index.htm. National Oceanic and Atmospheric Administration, 1985, Digital magnetic declination: National Geophysical Data Center,

at http://w w w .ngdc. noaa.gov/geomagmodels/struts/calcDeclination. Stoeser, D.B., Green, G.N., Morath, L.C., Heran, W .D., W ilson, A.B., Moore, D.W ., and V an Gosen, B.S., 2005, P reliminary

integrated geologic map databases for the U nited States— Central states— Montana, W yoming, Colorado, New Mexico, North Dak ota, South Dak ota, Nebrask a, Kansas, Ok lahoma, Texas, Iow a, Missouri, Ark ansas, and Louisiana: U .S. Geological Survey Open-File R eport 2005-1351, 18 p.

U .S. Census Bureau, 1996, Cities, tow ns, census designated places of W yoming at 1:100,000, at http://w ygl.w ygisc.org/w ygeolib/catalog/main/home.page.

U .S. Census Bureau, 1997, W yoming roads at 1:100,000, at http://piney.w ygisc.uw yo.edu/data/transportation/road100k .zip. U .S. Geological Survey, 2002, The National Elevation Dataset: P hotogrammetric Engineering and R emote Sensing, v. 68,

no. 1, at http://ned.usgs.gov. W yoming Geographic Information Science Center, 1997, Internet mapping service— Basemap data for W yoming: Spatial

Data and V isualization Center, at http://w ygl.w ygisc.org/w ygeolib/catalog/main/home.page.

BASIN LOCATION MAP

Edited by Phyllis A. Ranz and Suzanne C. LuhrDigital cartography and layout by Suzanne C. Luhr

Geology modified from Love and Christiansen (1985)

Kle

Formation contact Normal fault— Dotted w here concealed; ball and bar on dow nthrow n block ; no designation

on fault trace indicates undetermined motion

Thrust fault— Dotted w here concealed; saw teeth on upthrow n (tectonically higher) block

:

( (

Magnetic Declination = 9° 38' Eat center of map(Feb. 12, 2013)

N MN

County boundaryState boundaryCity or tow n

County seat_

U

Lak e or reservoir

Interstate highw ayU .S. highw ayState highw ayCounty or other road

§̈¦8 0(/3 0

!(89

")1

Twmo

Tw

Twk

Tfu

Tftr

Tftl

Tfl

Tflt

Tft

M O N T A N A

SOUTH D A K O

TAN E B R A S K A