United StatesDepartment ofAgriculture

NaturalResourcesConservationService

Soil Survey ofRock IslandCounty, Illinois

In cooperation with IllinoisAgricultural ExperimentStation

The Natural Resources Conservation Service (NRCS) is committed to making itsinformation accessible to all of its customers and employees. If you are experiencingaccessibility issues and need assistance, please contact our Helpdesk by phone at1-800-457-3642 or by e-mail at helpdesk@helpdesk.itc.nrcs.usda.gov. For assistancewith publications that include maps, graphs, or similar forms of information, you mayalso wish to contact our State or local office. You can locate the correct office andphone number at http://offices.sc.egov.usda.gov/locator/app.

NRCS Accessibility Statement

http://offices.sc.egov.usda.gov/locator/appmailto:helpdesk@helpdesk.itc.nrcs.usda.gov

This publication consists of a manuscript and a set of soil maps. The information provided can be useful in planningthe use and management of small areas.

To find information about your area of interest, locate that area on the Index to Map Sheets. Note the number ofthe map sheet, and turn to that sheet.

Locate your area of interest on the map sheet. Note the map unit symbols that are in that area. Turn to theNumerical Index to Map Units, which lists the map units by symbol and name and shows the page where eachmap unit is described. The map unit symbols and names also appear as bookmarks, which link directly to theappropriate page in the publication.

The Contents shows which table has data on a specific land use for each soil map unit. Also see the Contents forother sections of this publication that may address your specific needs.

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How To Use This Soil Survey

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Additional information about the Nation’s natural resources is available on theNatural Resources Conservation Service homepage on the World Wide Web. Theaddress is http://www.nrcs.usda.gov.

This soil survey is a publication of the National Cooperative Soil Survey, a joint effortof the United States Department of Agriculture and other Federal agencies, Stateagencies including the Agricultural Experiment Stations, and local agencies. TheNatural Resources Conservation Service (formerly the Soil Conservation Service) hasleadership for the Federal part of the National Cooperative Soil Survey.

Major fieldwork for this soil survey was completed in 1998. Soil names anddescriptions were approved in 1998. Unless otherwise indicated, statements in thispublication refer to conditions in the survey area in 1998. This survey was madecooperatively by the Natural Resources Conservation Service and the IllinoisAgricultural Experiment Station. It is part of the technical assistance furnished to theRock Island County Soil and Water Conservation District. Financial assistance wasprovided by the Rock Island County Board and the Illinois Department of Agriculture.

Soil maps in this survey may be copied without permission. Enlargement of thesemaps, however, could cause misunderstanding of the detail of mapping. If enlarged,maps do not show the small areas of contrasting soils that could have been shown at alarger scale.

The United States Department of Agriculture (USDA) prohibits discrimination in all ofits programs on the basis of race, color, national origin, gender, religion, age, disability,political beliefs, sexual orientation, and marital or family status. (Not all prohibited basesapply to all programs.) Persons with disabilities who require alternative means forcommunication of program information (Braille, large print, audiotape, etc.) shouldcontact the USDA’s TARGET Center at 202-720-2600 (voice or TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights,Room 326W, Whitten Building, 14th and Independence Avenue SW, Washington, DC20250-9410, or call 202-720-5964 (voice or TDD). USDA is an equal opportunityprovider and employer.

Cover: A view from the loess hill bluffs overlooking the Mississippi River Valley.

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Contents

How To Use This Soil Survey ................................. 3Numerical Index to Map Units ............................. 10Foreword ............................................................... 13General Nature of the Survey Area ......................... 15

Settlement, Industry, and Farming ...................... 15Relief, Physiography, and Drainage .................... 16Climate ............................................................... 17

How This Survey Was Made ................................... 18Formation and Classification of the Soils .......... 21

Factors of Soil Formation ................................... 21Parent Material ............................................... 21Living Organisms ........................................... 21Climate ........................................................... 21Topography .................................................... 21Time ............................................................... 22

Classification of the Soils .................................... 22Soil Series and Detailed Soil Map Units .............. 25

Ambraw Series ................................................... 268302A—Ambraw loam, 0 to 2 percent

slopes, occasionally flooded ........................ 27Atlas Series ........................................................ 27Atterberry Series ................................................ 2861A—Atterberry silt loam, 0 to 2 percent

slopes .......................................................... 29Biggsville Series ................................................. 30671A—Biggsville silt loam, 0 to 2 percent

slopes .......................................................... 30671B—Biggsville silt loam, 2 to 5 percent

slopes .......................................................... 31Birds Series ........................................................ 311334A—Birds silt loam, undrained, 0 to 2

percent slopes, frequently flooded ............... 32Bold Series ......................................................... 32Buckhart Series .................................................. 33705A—Buckhart silt loam, 0 to 2 percent

slopes .......................................................... 34Burkhardt Series ................................................ 34961A—Burkhardt-Saude complex, 0 to 2

percent slopes ............................................. 35Calco Series ....................................................... 351400A—Calco silty clay loam, undrained,

0 to 2 percent slopes, frequently flooded ..... 36

3400A—Calco silty clay loam, 0 to 2 percentslopes, frequently flooded ............................ 36

8400A—Calco silty clay loam, 0 to 2 percentslopes, occasionally flooded ........................ 37

Chute Series ...................................................... 37Coatsburg Series ............................................... 38Coffeen Series ................................................... 393428A—Coffeen silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 407428A—Coffeen silt loam, 0 to 2 percent

slopes, rarely flooded ................................... 40Coloma Series .................................................... 41689B—Coloma sand, 1 to 7 percent slopes ....... 41689D—Coloma sand, 7 to 15 percent

slopes .......................................................... 42Coyne Series ...................................................... 42764A—Coyne fine sandy loam, 0 to 2

percent slopes ............................................. 43764C—Coyne fine sandy loam, 5 to 10

percent slopes ............................................. 44Denny Series ...................................................... 4445A—Denny silt loam, 0 to 2 percent slopes ...... 45Dickinson Series ................................................ 4687A—Dickinson sandy loam, 0 to 2 percent

slopes .......................................................... 4687C2—Dickinson sandy loam, 5 to 10

percent slopes, eroded ................................ 47Dorchester Series .............................................. 473239A—Dorchester silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 487239A—Dorchester silt loam, 0 to 2 percent

slopes, rarely flooded ................................... 48Elkhart Series ..................................................... 49567C2—Elkhart silt loam, 5 to 10 percent

slopes, eroded ............................................. 50567D2—Elkhart silt loam, 10 to 18 percent

slopes, eroded ............................................. 50Fayette Series .................................................... 51280B—Fayette silt loam, 2 to 5 percent

slopes .......................................................... 51280B2—Fayette silt loam, 2 to 5 percent

slopes, eroded ............................................. 52

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280C2—Fayette silt loam, 5 to 10 percentslopes, eroded ............................................. 52

280C3—Fayette silty clay loam, 5 to 10percent slopes, severely eroded .................. 53

3646L—Fluvaquents, loamy, 0 to 2 percentslopes, frequently flooded, long duration ...... 53

Greenbush Series .............................................. 54675A—Greenbush silt loam, 0 to 2 percent

slopes .......................................................... 55675B—Greenbush silt loam, 2 to 5 percent

slopes .......................................................... 55Hickory Series .................................................... 568D2—Hickory silt loam, 10 to 18 percent

slopes, eroded ............................................. 578D3—Hickory clay loam, 10 to 18 percent

slopes, severely eroded ............................... 578F—Hickory silt loam, 18 to 35 percent

slopes .......................................................... 588F3—Hickory clay loam, 18 to 35 percent

slopes, severely eroded ............................... 58898F3—Hickory-Sylvan complex, 18 to 35

percent slopes, severely eroded .................. 59898G—Hickory-Sylvan silt loams, 35 to 60

percent slopes ............................................. 59946D3—Hickory-Atlas complex, 10 to 18

percent slopes, severely eroded .................. 60946F3—Hickory-Atlas complex, 18 to 35

percent slopes, severely eroded .................. 61960D2—Hickory-Sylvan-Fayette silt loams,

10 to 18 percent slopes, eroded ................... 61960D3—Hickory-Sylvan-Fayette complex,

10 to 18 percent slopes, severely eroded ..... 62960F—Hickory-Sylvan-Fayette silt loams,

18 to 30 percent slopes ................................ 63Hoopeston Series ............................................... 64172A—Hoopeston sandy loam, 0 to 2

percent slopes ............................................. 65Joslin Series ....................................................... 65525A—Joslin loam, bedrock substratum,

0 to 2 percent slopes.................................... 66763A—Joslin silt loam, 0 to 2 percent

slopes .......................................................... 66

763B—Joslin silt loam, 2 to 5 percentslopes .......................................................... 67

Joy Series .......................................................... 67275A—Joy silt loam, 0 to 2 percent slopes ......... 68Landes Series .................................................... 697304A—Landes fine sandy loam, 0 to 2

percent slopes, rarely flooded ...................... 69Lawler Series ..................................................... 70647A—Lawler loam, 0 to 2 percent slopes ......... 71Lawson Series .................................................... 713451A—Lawson silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 727451A—Lawson silt loam, 0 to 2 percent

slopes, rarely flooded ................................... 72Marseilles Series ................................................ 72913D2—Marseilles-Hickory silt loams, 10

to 18 percent slopes, eroded........................ 73913F—Marseilles-Hickory silt loams, 18 to

35 percent slopes ........................................ 74913G—Marseilles-Hickory silt loams, 35 to

60 percent slopes ........................................ 75Martinsville Series .............................................. 75570B—Martinsville silt loam, 2 to 5 percent

slopes .......................................................... 76570C3—Martinsville clay loam, 5 to 10

percent slopes, severely eroded .................. 77570D3—Martinsville clay loam, 10 to 18

percent slopes, severely eroded .................. 77Millington Series ................................................. 781082A—Millington silt loam, undrained,

0 to 2 percent slopes, frequently flooded ..... 783082A—Millington silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 79Millsdale Series .................................................. 79317A—Millsdale silty clay loam, 0 to 2

percent slopes ............................................. 80M-W—Miscellaneous water ................................ 80Moline Series ..................................................... 801654A—Moline silty clay, undrained, 0 to 2

percent slopes, frequently flooded ............... 817654A—Moline silty clay, 0 to 2 percent

slopes, rarely flooded ................................... 81

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Muscatune Series .............................................. 8251A—Muscatune silt loam, 0 to 2 percent

slopes .......................................................... 83Niota Series........................................................ 83261A—Niota silt loam, 0 to 2 percent

slopes .......................................................... 84Oakville Series ................................................... 85741F—Oakville fine sand, 20 to 30 percent

slopes .......................................................... 85917C2—Oakville-Tell complex, 5 to 10

percent slopes, eroded ................................ 85917D2—Oakville-Tell complex, 10 to 18

percent slopes, eroded ................................ 86Orion Series ....................................................... 873415A—Orion silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 877415A—Orion silt loam, 0 to 2 percent

slopes, rarely flooded ................................... 88802B—Orthents, loamy, undulating .................... 88Osco Series ....................................................... 8986B—Osco silt loam, 2 to 5 percent slopes ........ 9086C2—Osco silt loam, 5 to 10 percent

slopes, eroded ............................................. 90Otter Series ........................................................ 911076A—Otter silt loam, undrained, 0 to 2

percent slopes, frequently flooded ............... 913076A—Otter silt loam, 0 to 2 percent slopes,

frequently flooded ........................................ 927076A—Otter silt loam, 0 to 2 percent slopes,

rarely flooded ............................................... 92864—Pits, quarries ............................................. 93865—Pits, gravel ................................................ 93800C—Psamments, sloping ............................... 93Raddle Series ..................................................... 93430A—Raddle silt loam, 0 to 2 percent

slopes .......................................................... 94430B—Raddle silt loam, 2 to 5 percent

slopes .......................................................... 95Radford Series ................................................... 953074A—Radford silt loam, 0 to 2 percent

slopes, frequently flooded ............................ 96Rozetta Series .................................................... 96

279A—Rozetta silt loam, 0 to 2 percentslopes .......................................................... 97

279B—Rozetta silt loam, 2 to 5 percentslopes .......................................................... 97

Sable Series ....................................................... 9868A—Sable silty clay loam, 0 to 2 percent

slopes .......................................................... 99Saude Series ...................................................... 99774A—Saude loam, 0 to 2 percent slopes ....... 100Sawmill Series .................................................. 1001107A—Sawmill silty clay loam, undrained,

0 to 2 percent slopes, frequentlyflooded ....................................................... 101

3107A—Sawmill silty clay loam, 0 to 2percent slopes, frequently flooded ............. 101

7107A—Sawmill silty clay loam, 0 to 2percent slopes, rarely flooded .................... 102

8107+—Sawmill silt loam, 0 to 2 percentslopes, occasionally flooded, overwash ..... 102

Seaton Series ................................................... 103274B—Seaton silt loam, 2 to 5 percent

slopes ........................................................ 104274B2—Seaton silt loam, 2 to 5 percent

slopes, eroded ........................................... 104274C2—Seaton silt loam, 5 to 10 percent

slopes, eroded ........................................... 105274D2—Seaton silt loam, 10 to 18 percent

slopes, eroded ........................................... 105943D2—Seaton-Timula silt loams, 10 to 18

percent slopes, eroded .............................. 105943F2—Seaton-Timula silt loams, 18 to 35

percent slopes, eroded .............................. 106Sparta Series ................................................... 10788A—Sparta loamy sand, 0 to 2 percent

slopes ........................................................ 107Strawn Series ................................................... 108959G—Strawn-Chute complex, 18 to 60

percent slopes ........................................... 108Stronghurst Series ........................................... 109278A—Stronghurst silt loam, 0 to 2 percent

slopes ........................................................ 110Sylvan Series ................................................... 110

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19C3—Sylvan silty clay loam, 5 to 10percent slopes, severely eroded ................ 111

19D—Sylvan silt loam, 10 to 18 percentslopes ........................................................ 112

19D3—Sylvan silty clay loam, 10 to 18percent slopes, severely eroded ................ 112

19F—Sylvan silt loam, 18 to 35 percentslopes ........................................................ 113

19F3—Sylvan silty clay loam, 18 to 35percent slopes, severely eroded ................ 113

962F—Sylvan-Bold silt loams, 18 to 35percent slopes ........................................... 114

Tell Series......................................................... 114Thebes Series .................................................. 115212B—Thebes silt loam, 2 to 5 percent

slopes ........................................................ 116Timula Series ................................................... 116Titus Series ...................................................... 1178404A—Titus silty clay loam, 0 to 2 percent

slopes, occasionally flooded ...................... 118Velma Series .................................................... 119250D—Velma silt loam, 10 to 18 percent

slopes ........................................................ 119944D2—Velma-Coatsburg silt loams, 10 to

18 percent slopes, eroded ......................... 120Wabash Series ................................................. 1203083A—Wabash silty clay, 0 to 2 percent

slopes, frequently flooded .......................... 1217083A—Wabash silty clay, 0 to 2 percent

slopes, rarely flooded ................................. 122Waukee Series ................................................. 122727A—Waukee loam, 0 to 2 percent

slopes ........................................................ 123Use and Management of the Soils .................... 125

Interpretive Ratings .......................................... 125Rating Class Terms ...................................... 125Numerical Ratings ........................................ 125

Crops and Pasture ........................................... 125Crop Yield Estimates .................................... 126Land Capability Classification ...................... 126Prime Farmland ........................................... 127

Forestland Management and Productivity ........ 127Windbreaks and Environmental Plantings ........ 129

Recreation ........................................................ 130Wildlife Habitat ................................................. 131Hydric Soils ...................................................... 132Engineering ...................................................... 133

Building Site Development ........................... 133Sanitary Facilities ......................................... 134Construction Materials ................................. 136Water Management ...................................... 137

Soil Properties .................................................... 139Engineering Index Properties ........................... 139Physical Properties .......................................... 140Chemical Properties ......................................... 141Water Features ................................................. 141Soil Features .................................................... 142

References .......................................................... 145Glossary .............................................................. 147Tables .................................................................. 157

Table 1.—Temperature and Precipitation .......... 158Table 2.—Freeze Dates in Spring and Fall ........ 159Table 3.—Growing Season ............................... 159Table 4.—Classification of the Soils .................. 160Table 5.—Acreage and Proportionate

Extent of the Soils ...................................... 162Table 6.—Land Capability and Yields per

Acre of Crops and Pasture ......................... 164Table 7.—Prime Farmland ................................ 170Table 8.—Forestland Productivity ..................... 172Table 9a.—Forestland Management ................. 177Table 9b.—Forestland Management ................. 182Table 9c.—Forestland Management ................. 187Table 9d.—Forestland Management ................. 191Table 9e.—Forestland Management ................. 194Table 10.—Windbreaks and Environmental

Plantings .................................................... 196Table 11a.—Recreation .................................... 220Table 11b.—Recreation .................................... 230Table 12.—Wildlife Habitat ................................ 239Table 13.—Hydric Soils .................................... 246Table 14a.—Building Site Development ............ 249Table 14b.—Building Site Development ............ 260Table 15.—Sanitary Facilities ........................... 273Table 16.—Construction Materials .................... 292Table 17a.—Water Management ...................... 312

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Table 17b.—Water Management ...................... 323Table 18.—Engineering Index Properties ......... 336Table 19.—Physical Properties of the Soils ...... 360

Table 20.—Chemical Properties of the Soils ..... 371Table 21.—Water Features ............................... 382Table 22.—Soil Features .................................. 389

Issued 2004

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8D2—Hickory silt loam, 10 to 18 percentslopes, eroded .................................................... 57

8D3—Hickory clay loam, 10 to 18 percentslopes, severely eroded ...................................... 57

8F—Hickory silt loam, 18 to 35 percentslopes ................................................................. 58

8F3—Hickory clay loam, 18 to 35 percentslopes, severely eroded ...................................... 58

19C3—Sylvan silty clay loam, 5 to 10 percentslopes, severely eroded .................................... 111

19D—Sylvan silt loam, 10 to 18 percentslopes ............................................................... 112

19D3—Sylvan silty clay loam, 10 to 18 percentslopes, severely eroded .................................... 112

19F—Sylvan silt loam, 18 to 35 percentslopes ............................................................... 113

19F3—Sylvan silty clay loam, 18 to 35 percentslopes, severely eroded .................................... 113

45A—Denny silt loam, 0 to 2 percentslopes ................................................................. 45

51A—Muscatune silt loam, 0 to 2 percentslopes ................................................................. 83

61A—Atterberry silt loam, 0 to 2 percentslopes ................................................................. 29

68A—Sable silty clay loam, 0 to 2 percentslopes ................................................................. 99

86B—Osco silt loam, 2 to 5 percent slopes ............ 9086C2—Osco silt loam, 5 to 10 percent slopes,

eroded ................................................................ 9087A—Dickinson sandy loam, 0 to 2 percent

slopes ................................................................. 4687C2—Dickinson sandy loam, 5 to 10 percent

slopes, eroded .................................................... 4788A—Sparta loamy sand, 0 to 2 percent

slopes ............................................................... 107172A—Hoopeston sandy loam, 0 to 2 percent

slopes ................................................................. 65212B—Thebes silt loam, 2 to 5 percent

slopes ............................................................... 116250D—Velma silt loam, 10 to 18 percent

slopes ............................................................... 119261A—Niota silt loam, 0 to 2 percent slopes .......... 84274B—Seaton silt loam, 2 to 5 percent

slopes ............................................................... 104

274B2—Seaton silt loam, 2 to 5 percentslopes, eroded .................................................. 104

274C2—Seaton silt loam, 5 to 10 percentslopes, eroded .................................................. 105

274D2—Seaton silt loam, 10 to 18 percentslopes, eroded .................................................. 105

275A—Joy silt loam, 0 to 2 percent slopes ............. 68278A—Stronghurst silt loam, 0 to 2 percent

slopes ............................................................... 110279A—Rozetta silt loam, 0 to 2 percent

slopes ................................................................. 97279B—Rozetta silt loam, 2 to 5 percent

slopes ................................................................. 97280B—Fayette silt loam, 2 to 5 percent

slopes ................................................................. 51280B2—Fayette silt loam, 2 to 5 percent

slopes, eroded .................................................... 52280C2—Fayette silt loam, 5 to 10 percent

slopes, eroded .................................................... 52280C3—Fayette silty clay loam, 5 to 10

percent slopes, severely eroded ......................... 53317A—Millsdale silty clay loam, 0 to 2 percent

slopes ................................................................. 80430A—Raddle silt loam, 0 to 2 percent

slopes ................................................................. 94430B—Raddle silt loam, 2 to 5 percent

slopes ................................................................. 95525A—Joslin loam, bedrock substratum,

0 to 2 percent slopes .......................................... 66567C2—Elkhart silt loam, 5 to 10 percent

slopes, eroded .................................................... 50567D2—Elkhart silt loam, 10 to 18 percent

slopes, eroded .................................................... 50570B—Martinsville silt loam, 2 to 5 percent

slopes ................................................................. 76570C3—Martinsville clay loam, 5 to 10 percent

slopes, severely eroded ...................................... 77570D3—Martinsville clay loam, 10 to 18

percent slopes, severely eroded ......................... 77647A—Lawler loam, 0 to 2 percent slopes ............. 71671A—Biggsville silt loam, 0 to 2 percent

slopes ................................................................. 30671B—Biggsville silt loam, 2 to 5 percent

slopes ................................................................. 31

Numerical Index to Map Units

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675A—Greenbush silt loam, 0 to 2 percentslopes ................................................................. 55

675B—Greenbush silt loam, 2 to 5 percentslopes ................................................................. 55

689B—Coloma sand, 1 to 7 percent slopes ............ 41689D—Coloma sand, 7 to 15 percent

slopes ................................................................. 42705A—Buckhart silt loam, 0 to 2 percent

slopes ................................................................. 34727A—Waukee loam, 0 to 2 percent slopes ......... 123741F—Oakville fine sand, 20 to 30 percent

slopes ................................................................. 85763A—Joslin silt loam, 0 to 2 percent slopes ......... 66763B—Joslin silt loam, 2 to 5 percent slopes ......... 67764A—Coyne fine sandy loam, 0 to 2 percent

slopes ................................................................. 43764C—Coyne fine sandy loam, 5 to 10

percent slopes .................................................... 44774A—Saude loam, 0 to 2 percent

slopes ............................................................... 100800C—Psamments, sloping ................................... 93802B—Orthents, loamy, undulating ........................ 88864—Pits, quarries ................................................. 93865—Pits, gravel .................................................... 93898F3—Hickory-Sylvan complex, 18 to 35

percent slopes, severely eroded ......................... 59898G—Hickory-Sylvan silt loams, 35 to 60

percent slopes .................................................... 59913D2—Marseilles-Hickory silt loams, 10 to 18

percent slopes, eroded ....................................... 73913F—Marseilles-Hickory silt loams, 18 to 35

percent slopes .................................................... 74913G—Marseilles-Hickory silt loams, 35 to 60

percent slopes .................................................... 75917C2—Oakville-Tell complex, 5 to 10 percent

slopes, eroded .................................................... 85917D2—Oakville-Tell complex, 10 to 18

percent slopes, eroded ....................................... 86943D2—Seaton-Timula silt loams, 10 to 18

percent slopes, eroded ..................................... 105943F2—Seaton-Timula silt loams, 18 to 35

percent slopes, eroded ..................................... 106944D2—Velma-Coatsburg silt loams, 10 to 18

percent slopes, eroded ..................................... 120

946D3—Hickory-Atlas complex, 10 to 18percent slopes, severely eroded ......................... 60

946F3—Hickory-Atlas complex, 18 to 35percent slopes, severely eroded ......................... 61

959G—Strawn-Chute complex, 18 to 60percent slopes .................................................. 108

960D2—Hickory-Sylvan-Fayette silt loams,10 to 18 percent slopes, eroded ......................... 61

960D3—Hickory-Sylvan-Fayette complex,10 to 18 percent slopes, severely eroded ........... 62

960F—Hickory-Sylvan-Fayette silt loams, 18to 30 percent slopes ........................................... 63

961A—Burkhardt-Saude complex, 0 to 2percent slopes .................................................... 35

962F—Sylvan-Bold silt loams, 18 to 35percent slopes .................................................. 114

1076A—Otter silt loam, undrained, 0 to 2percent slopes, frequently flooded ...................... 91

1082A—Millington silt loam, undrained, 0 to 2percent slopes, frequently flooded ...................... 78

1107A—Sawmill silty clay loam, undrained,0 to 2 percent slopes, frequently flooded .......... 101

1334A—Birds silt loam, undrained, 0 to 2percent slopes, frequently flooded ...................... 32

1400A—Calco silty clay loam, undrained, 0 to 2percent slopes, frequently flooded ...................... 36

1654A—Moline silty clay, undrained, 0 to 2percent slopes, frequently flooded ...................... 81

3074A—Radford silt loam, 0 to 2 percentslopes, frequently flooded................................... 96

3076A—Otter silt loam, 0 to 2 percent slopes,frequently flooded ............................................... 92

3082A—Millington silt loam, 0 to 2 percentslopes, frequently flooded................................... 79

3083A—Wabash silty clay, 0 to 2 percentslopes, frequently flooded................................. 121

3107A—Sawmill silty clay loam, 0 to 2 percentslopes, frequently flooded................................. 101

3239A—Dorchester silt loam, 0 to 2 percentslopes, frequently flooded................................... 48

3400A—Calco silty clay loam, 0 to 2 percentslopes, frequently flooded................................... 36

3415A—Orion silt loam, 0 to 2 percent slopes,frequently flooded ............................................... 87

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3428A—Coffeen silt loam, 0 to 2 percentslopes, frequently flooded................................... 40

3451A—Lawson silt loam, 0 to 2 percentslopes, frequently flooded................................... 72

3646L—Fluvaquents, loamy, 0 to 2 percentslopes, frequently flooded, longduration .............................................................. 53

7076A—Otter silt loam, 0 to 2 percent slopes,rarely flooded ..................................................... 92

7083A—Wabash silty clay, 0 to 2 percentslopes, rarely flooded ....................................... 122

7107A—Sawmill silty clay loam, 0 to 2 percentslopes, rarely flooded ....................................... 102

7239A—Dorchester silt loam, 0 to 2 percentslopes, rarely flooded ......................................... 48

7304A—Landes fine sandy loam, 0 to 2 percentslopes, rarely flooded ......................................... 69

7415A—Orion silt loam, 0 to 2 percent slopes,rarely flooded ..................................................... 88

7428A—Coffeen silt loam, 0 to 2 percentslopes, rarely flooded ......................................... 40

7451A—Lawson silt loam, 0 to 2 percentslopes, rarely flooded ......................................... 72

7654A—Moline silty clay, 0 to 2 percentslopes, rarely flooded ......................................... 81

8107+—Sawmill silt loam, 0 to 2 percentslopes, occasionally flooded, overwash ............ 102

8302A—Ambraw loam, 0 to 2 percentslopes, occasionally flooded ............................... 27

8400A—Calco silty clay loam, 0 to 2 percentslopes, occasionally flooded ............................... 37

8404A—Titus silty clay loam, 0 to 2 percentslopes, occasionally flooded ............................. 118

M-W—Miscellaneous water .................................... 80

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This soil survey contains information that affects land use planning in this surveyarea. It contains predictions of soil behavior for selected land uses. The survey alsohighlights soil limitations, improvements needed to overcome the limitations, and theimpact of selected land uses on the environment.

This soil survey is designed for many different users. Farmers, foresters, andagronomists can use it to evaluate the potential of the soil and the management neededfor maximum food and fiber production. Planners, community officials, engineers,developers, builders, and home buyers can use the survey to plan land use, select sitesfor construction, and identify special practices needed to ensure proper performance.Conservationists, teachers, students, and specialists in recreation, wildlifemanagement, waste disposal, and pollution control can use the survey to help themunderstand, protect, and enhance the environment.

Various land use regulations of Federal, State, and local governments may imposespecial restrictions on land use or land treatment. The information in this report isintended to identify soil properties that are used in making various land use or landtreatment decisions. Statements made in this report are intended to help the land usersidentify and reduce the effects of soil limitations on various land uses. The landowner oruser is responsible for identifying and complying with existing laws and regulations.

Great differences in soil properties can occur within short distances. Some soils areseasonally wet or subject to flooding. Some are shallow to bedrock. Some are toounstable to be used as a foundation for buildings or roads. Clayey or wet soils arepoorly suited to use as septic tank absorption fields. A high water table makes a soilpoorly suited to basements or underground installations.

These and many other soil properties that affect land use are described in this soilsurvey. The location of each soil is shown on the detailed soil maps. Each soil in thesurvey area is described, and information on specific uses is given. Help in using thispublication and additional information are available at the local office of the NaturalResources Conservation Service or the Cooperative Extension Service.

William J. GradleState ConservationistNatural Resources Conservation Service

Foreword

15

ROCK ISLAND COUNTY is in northwestern Illinois(fig. 1). It has a total area of about 288,910 acres, or451 square miles. It is bounded by Whiteside andHenry Counties on the east, by Mercer County on thesouth, and by the Mississippi River on the west andnorth.

This soil survey updates the survey of Rock IslandCounty published in 1977 (Acker, 1977). It providesadditional information and has larger maps, whichshow the soils in greater detail.

General Nature of the Survey AreaThis section provides some general information

about the survey area. It describes settlement,industry, and farming; relief, physiography, anddrainage; and climate.

Settlement, Industry, and Farming

This section was originally written by the late Emil Kubalek,former district conservationist, Rock Island County.

Rock Island County was established in 1831. In2000, the population of the county was 149,374 andthat of Rock Island, the county seat, was 39,684 (U.S.Department of Commerce, 2002).

The center of the county is part of the metropolitan

complex known as the Quad Cities. This metropolitanarea includes Davenport and Bettendorf in Iowa andRock Island and Moline in Illinois.

The county has a well developed transportationsystem. Interstate Highway 74 and U.S. Highways 6,67, and 150 bisect the county from north to south.Interstate 80 and Interstate 280 cross the county fromeast to west. The county also has several State roads.The main secondary roads are blacktop. Railroadsfurnish freight service to the county. Facilities forloading commodities onto river barges are availablealong the Mississippi River. The Quad City Airportoffers connections to all points throughout the UnitedStates.

The Quad Cities is considered the “tractor capital ofthe world.” The county has several small industries andis also the home of the U.S. Army WeaponsCommand, Rock Island Arsenal. Several limestonequarries and gravel pits provide crushed rock forroads, finely ground material for limestone applicationon fields, and sand and gravel for building materials.Hybrid seed corn is produced in the county. CordovaTownship also has a large industrial complex. Thenuclear generating station in Cordova Townshipprovides power for much of east-central Iowa andnorthwestern Illinois and generates power for theChicago metropolitan region.

The Quad Cities area offers many educational

Soil Survey of

Rock Island County, IllinoisBy Steve Elmer, Natural Resources Conservation Service

Original fieldwork by L.L. Acker, R.D. Busby, L.A. Dungan, G.T. Keller, R. Rehner,L.M. Reinebach, J.A. Thompson, and S.E. Zwicker

Updated fieldwork by Steve Elmer and Dave Preloger, Natural Resources ConservationService

Compilation and resource analysis by Steve Elmer, Frank Heisner, Amy Kuhel, DavePreloger, and Jonathan Wald, Natural Resources Conservation Service

United States Department of Agriculture, Natural Resources Conservation Service,in cooperation with the Illinois Agricultural Experiment Station

16 Soil Survey of

facilities. Augustana College, Western IllinoisUniversity, and Blackhawk Junior College are on theIllinois side of the Mississippi River. St. AmbroseCollege and Scott County Junior College are on theIowa side of the river.

Farming has been a major enterprise in Rock IslandCounty since its settlement. In 2000, there were 318farms in the county (Illinois Agricultural StatisticsService, 2001). Crops and livestock are raised in thesurvey area.

Corn and soybeans are the main crops. In 2000,the acreage used for corn was 65,000 and theacreage used for soybeans was 55,000 (IllinoisAgricultural Statistics Service, 2001). Small grain andhay also are grown in the county, and there are severalapple orchards.

The total number of cattle in 2000 was 11,000, and

the total number of swine was 35,900 (IllinoisAgricultural Statistics Service, 2001). Sheep andchickens also are raised.

Relief, Physiography, and Drainage

Dr. Richard C. Anderson, retired, Department of Geology,Augustana College, helped prepare this section.

The topography of Rock Island County consists ofupland plains, highly dissected valley sides, terraces,and flood plains (fig. 2). Although the county wascovered by glaciers that greatly modified the pre-existing landscape, the present topography is almostentirely the result of stream erosion (Willman andFrye, 1970). Thus the upland plains represent a gentlyrolling surface produced by glacial deposition, and the

LEGEND

95B—Southern Wisconsin and Northern Illinois DriftPlain

98—Southern Michigan and Northern Indiana DriftPlain

105—Northern Mississippi Valley Loess Hills

108A and 108B—Illinois and Iowa Deep Loess andDrift

110—Northern Illinois and Indiana Heavy Till Plain

113—Central Claypan Area

114B—Southern Illinois and Indiana Thin Loess andTill Plain

115A, 115B, and 115C—Central Mississippi ValleyWooded Slopes

120A—Kentucky and Indiana Sandstone and ShaleHills and Valleys

131A—Southern Mississippi Valley Alluvium

134—Southern Mississippi Valley Silty Uplands

Figure 1.—Location of Rock Island County and major land resource areas (MLRAs) in Illinois.

Rock Island County, Illinois 17

flood plains and dissected valley sides are the result ofsubsequent stream erosion (Leighton and Brophy,1961).

The upland plains are at elevations of 750 to 790feet between the Mississippi River and Copperas andMill Creeks. They are at an elevation of about 810 feetsouth of Copperas and Mill Creeks and at an elevationof about 700 feet in Coe Township at the northern endof the county. The upland areas are remnants of aonce-continuous glacial plain that extended far to thesouth and east (Leighton and Brophy, 1961). Althoughlargely of glacial origin, the upland areas are coveredwith 30 feet or more of wind-deposited loess. In mostplaces the loess is simply a veneer without atopographic expression of its own, but in CoeTownship it has been deposited in long, narrow ridgesas much as 50 feet high that give the topography adistinct northwest-southeast orientation. Sand dunesare on uplands in the extreme western part of thecounty and in Coe Township.

The flood plains are chiefly along the Mississippiand Rock Rivers and on the Meredosia bottom lands.The elevation on the flood plains ranges from 540 feetat the southwestern end of the county to 610 feet onthe sand plains in the northern part. Flood plains are

the floors of the valleys cut by the streams. The lowerareas are subject to periodic flooding. The flood plainsare underlain by water-deposited sand, silt, and clay.They are relatively shallow over limestone and shalebedrock. In the extreme northern end of the county,however, bedrock is at a depth of more than 100 feet.Sand and silt terraces are common on the flood plains.

Erosion by tributaries of the Mississippi and RockRivers has produced highly dissected topographyadjacent to these main streams. In many places thelocal relief varies by more than 200 feet. Steep slopescause landslides and soil instability.

The Mississippi River serves as the water sourcefor Rock Island, Moline, and East Moline, and thesmaller towns and rural areas are supplied by wellspumping from limestone crevices at depths of 100 to300 feet.

Climate

Table 1 gives data on temperature and precipitationfor the survey area as recorded at Moline during theperiod 1971 to 2000. Table 2 shows probable dates ofthe first freeze in fall and the last freeze in spring.Table 3 provides data on length of the growing season.

Figure 2.—A physiographic map of Rock Island County.

18 Soil Survey of

In winter, the average temperature is 25 degrees Fand the average daily minimum temperature is 16degrees. The lowest temperature on record, whichoccurred at Moline on February 3, 1996, is -28degrees. In summer, the average temperature is 73degrees and the average daily maximum temperatureis 84 degrees. The highest recorded temperature,which occurred at Moline on August 18, 1936, is 106degrees.

Growing degree days are shown in table 1. Theyare equivalent to “heat units.” During the month,growing degree days accumulate by the amount thatthe average temperature each day exceeds a basetemperature (50 degrees F). The normal monthlyaccumulation is used to schedule single or successiveplantings of a crop between the last freeze in springand the first freeze in fall.

Total annual precipitation is 38.04 inches. Of thistotal, 24.30 inches, or about 64 percent, usually falls inApril through September. The growing season for mostcrops falls within this period. In 2 years out of 10, therainfall in April through September is less than 11.85inches. The heaviest 1-day rainfall during the period ofrecord was 6.21 inches.

The average seasonal snowfall is 33.7 inches. Thegreatest snow depth at any one time during the periodof record was 29 inches. On average, 47 days of theyear have at least 1 inch of snow on the ground. Thenumber of such days varies greatly from year to year.

How This Survey Was MadeThis survey was made to provide updated

information about the soils and miscellaneous areas inRock Island County, which is a subset of Major LandResource Areas 108B and 115C (fig. 1). Major landresource areas (MLRAs) are geographicallyassociated land resource units that share a commonland use, elevation, topography, climate, water, soils,and vegetation (USDA, 1981). Map unit design and thesoil descriptions are based on the occurrence of eachsoil throughout the MLRA. In some cases a soil maybe referred to that was not mapped in the Rock IslandCounty subset but that is representative of the MLRA.

The information includes a description of the soilsand miscellaneous areas and their location and adiscussion of their properties and the subsequenteffects on suitability, limitations, and management forspecified uses. Soil scientists observed the steepness,length, and shape of the slopes; the general pattern ofdrainage; the kinds of crops and native plants; and thekinds of bedrock. They dug many holes to study thesoil profile, which is the sequence of natural layers, orhorizons, in a soil. The profile extends from the surface

down into the unconsolidated material in which the soilformed. The unconsolidated material is devoid of rootsand other living organisms and has not been changedby other biological activity.

The soils and miscellaneous areas in the surveyarea are in an orderly pattern that is related to thegeology, landforms, relief, climate, and naturalvegetation of the area. Each kind of soil andmiscellaneous area is associated with a particular kindor segment of the landscape. By observing the soilsand miscellaneous areas in the survey area andrelating their position to specific segments of thelandscape, soil scientists develop a concept, or model,of how the soils were formed. Thus, during mapping,this model enables the soil scientists to predict with aconsiderable degree of accuracy the kind of soil ormiscellaneous area at a specific location on thelandscape.

Individual soils on the landscape commonly mergeinto one another as their characteristics graduallychange. To construct an accurate map, however, soilscientists must determine the boundaries between thesoils. They can observe only a limited number of soilprofiles. Nevertheless, these observations,supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient toverify predictions of the kinds of soil in an area and todetermine the boundaries.

Soil scientists recorded the characteristics of thesoil profiles that they studied. They noted soil color,texture, size and shape of soil aggregates, kind andamount of rock fragments, distribution of plant roots,soil reaction, and other features that enable them toidentify soils. After describing the soils in the surveyarea and determining their properties, the soilscientists assigned the soils to taxonomic classes(units). Taxonomic classes are concepts. Eachtaxonomic class has a set of soil characteristics withprecisely defined limits. The classes are used as abasis for comparison to classify soils systematically.Soil taxonomy, the system of taxonomic classificationused in the United States, is based mainly on the kindand character of soil properties and the arrangementof horizons within the profile. After the soil scientistsclassified and named the soils in the survey area, theycompared the individual soils with similar soils in thesame taxonomic class in other areas so that theycould confirm data and assemble additional databased on experience and research.

While a soil survey is in progress, samples of someof the soils in the area generally are collected forlaboratory analyses and for engineering tests. Soilscientists interpret the data from these analyses andtests as well as the field-observed characteristics and

Rock Island County, Illinois 19

the soil properties to determine the expected behaviorof the soils under different uses. Interpretations for allof the soils are field tested through observation of thesoils in different uses and under different levels ofmanagement. Interpretations are modified asnecessary to fit local conditions, and some newinterpretations are developed to meet local needs.Data are assembled from other sources, such asresearch information, production records, and fieldexperience of specialists. For example, data on cropyields under defined levels of management areassembled from farm records and from field or plotexperiments on the same kinds of soil.

Predictions about soil behavior are based not onlyon soil properties but also on such variables as

climate and biological activity. Soil conditions arepredictable over long periods of time, but they are notpredictable from year to year. For example, soilscientists can predict with a fairly high degree ofaccuracy that a given soil will have a seasonal highwater table within certain depths in most years, butthey cannot predict that the water table will always beat a specific level in the soil on a specific date.

After soil scientists located and identified thesignificant natural bodies of soil in the survey area,they drew the boundaries of these bodies on aerialphotographs and identified each as a specific mapunit. Aerial photographs show trees, buildings, fields,roads, and rivers, all of which help in locatingboundaries accurately.

21

This section relates the soils in the survey area tothe major factors of soil formation and describes thesystem of soil classification.

Factors of Soil FormationThe principal factors of soil formation are parent

material, climate, plant and animal life, topography,and time (Jenny, 1941). The relative importance ofeach factor differs from place to place, and each factormodifies the effect of the other four. In some casesone factor may dominate the formation of a soil.Human activities, such as clearing forests, cultivatingthe soils, and using fertilizers, also change the courseof soil formation.

Parent Material

Peoria loess is the predominant parent material ofthe soils in Rock Island County (University of Illinois,1971). The Mississippi River Valley was the mainsource of the loess. The loess is about 30 feet thick onnearly level uplands. Muscatune and Rozetta soilsformed in these thick deposits of loess. In areas onslopes where the loess is thin or has been removed byerosion, the soils formed in such parent material asIllinoian till or Pennsylvania shale. Hickory soils formedin Illinoian till, and Marseilles soils formed inPennsylvania shale.

Terraces are in the valleys of the Mississippi andRock Rivers and in the valleys of the larger creeks. Onsome of these terraces, Niota and Moline soils formedin fine textured sediment. On other terraces, Spartaand Dickinson soils formed in sandy parent material.

Medium and moderately fine textured soils formedin alluvium in the valleys of the Mississippi and RockRivers. Coffeen and Sawmill soils are common inthese river valleys. In the smaller valleys, soils formedmainly in recent medium textured sediment washedfrom the uplands. Dorchester, Radford, and Orion soilsare examples.

Living Organisms

Plants have had a greater effect than animals onthe formation of soils in the survey area, but theanimals and organisms that live on and in the soilsalso have been important. The changes they bringabout depend mainly on the kind of life processesdistinctive to each. The kinds of plants and animalsthat live on and in the soils are affected, in turn, by theclimate, the parent material, the topography, and theage of the soil.

Some soils in the county formed under trees, andothers formed under prairie grasses. Most of thesloping soils formed mainly under such trees as oakand hickory. The nearly level soils formed under prairiegrasses. These soils have a darker, thicker surfacelayer than that of the soils that formed under forestvegetation and have a higher content of organicmatter.

Climate

Climate affects the formation of soils through itsinfluence on the rate of weathering of parent material.The humid, temperate climate of the countycontributes to the relatively rapid breakdown of soilminerals, to the formation of clay, and to the movementof these materials downward in the soil profile. Most ofthe upland soils in the county have considerably moreclay in the subsoil than in the surface layer.

Topography

Relief influences the amount of runoff, the degree oferosion, and the amount of water infiltrating andpercolating through the soil profile. Where the soilsformed in uniform, permeable parent materials, suchas loess, natural drainage is closely associated withslope. The moderately well drained and well drainedsoils are in the more rolling areas, and the somewhatpoorly drained to very poorly drained soils are mainly

Formation and Classification of the Soils

22 Soil Survey of

on flats or in depressions. Slopes in the county rangefrom less than 2 percent on the bottom land and in thenearly level uplands to more than 60 percent on thesteeper parts of the uplands that border valleys.

Time

The length of time necessary for the developmentof a soil depends on the other factors of soil formation.Soils that formed in parent material low in calcium(lime) develop more readily and become acid morereadily than soils that formed in material high incalcium. Permeable soils are leached of calcium andother soluble minerals much more rapidly than slowlypermeable soils. Soils form more quickly under forestvegetation than under prairie vegetation becausegrasses are more efficient in recycling calcium andother bases from the subsoil to the surface layer. Soilsgenerally form more quickly in a humid climate than ina dry climate.

In general, the longer the soils have been exposedto weathering processes, the more strongly developedthey are and the more evidence they show of horizondifferentiation. Most of the soils on uplands aremoderately developed. The soils in the western andnorthern parts of the county and on terraces, however,are only weakly developed. Because there has notbeen enough time for changes to take place, most ofthe soils on bottom land have no horizon differentiationor have only weakly expressed horizon differentiation.

Organic matter has accumulated in all of the soils.Soils that formed under prairie vegetation have athicker, darker surface layer than that of the soils thatformed under forest vegetation. In the poorly drainedsoils, iron compounds have been reduced and moveddownward in the profile. This process results in graycolors in the subsoil. Some of this iron hasaccumulated as concretions or small, round pellets. Inthe well drained soils, the iron compounds are oxidizedand are generally more diffuse. They result in ayellowish brown subsoil.

Classification of the SoilsThe system of soil classification used by the

National Cooperative Soil Survey has six categories(Soil Survey Staff, 1999). Beginning with the broadest,these categories are the order, suborder, great group,subgroup, family, and series. Classification is based onsoil properties observed in the field or inferred fromthose observations or from laboratory measurements.

Table 4 shows the classification of the soils in thesurvey area. The categories are defined in thefollowing paragraphs.

ORDER. Twelve soil orders are recognized. Thedifferences among orders reflect the dominant soil-forming processes and the degree of soil formation.Each order is identified by a word ending in sol. Anexample is Mollisol.

SUBORDER. Each order is divided into subordersprimarily on the basis of properties that influence soilgenesis and are important to plant growth orproperties that reflect the most important variableswithin the orders. The last syllable in the name of asuborder indicates the order. An example is Aquoll(Aqu, meaning water, plus oll, from Mollisol).

GREAT GROUP. Each suborder is divided intogreat groups on the basis of close similarities in kind,arrangement, and degree of development ofpedogenic horizons; soil moisture and temperatureregimes; and base status. Each great group isidentified by the name of a suborder and by a prefixthat indicates a property of the soil. An example isEndoaquolls (Endo, meaning within, plus aquoll, thesuborder of the Mollisols that has an aquic moistureregime).

SUBGROUP. Each great group has a typicsubgroup. Other subgroups are intergrades orextragrades. The typic is the central concept of thegreat group; it is not necessarily the most extensive.Intergrades are transitions to other orders, suborders,or great groups. Extragrades have some propertiesthat are not representative of the great group but donot indicate transitions to any other known kind of soil.Each subgroup is identified by one or more adjectivespreceding the name of the great group. The adjectiveTypic identifies the subgroup that typifies the greatgroup. An example is Typic Endoaquolls.

FAMILY. Families are established within asubgroup on the basis of physical and chemicalproperties and other characteristics that affectmanagement. Generally, the properties are those ofhorizons below plow depth where there is muchbiological activity. Among the properties andcharacteristics considered are particle-size class,mineral content, cation-exchange capacity,temperature regime, thickness of the root zone,consistence, moisture equivalent, slope, andpermanent cracks. A family name consists of thename of a subgroup preceded by terms that indicatesoil properties. An example is fine-silty, mixed,superactive, mesic Typic Endoaquolls.

Rock Island County, Illinois 23

SERIES. The series consists of soils that havesimilar horizons in their profile. The horizons aresimilar in color, texture, structure, reaction,consistence, mineral and chemical composition, and

arrangement in the profile. The texture of the surfacelayer or of the substratum can differ within a series.The Sable series is an example of a soil series in thissurvey area.

25

In this section, arranged in alphabetical order, eachsoil series recognized in the survey area is described.Each series description is followed by detaileddescriptions of the associated soil map units.

Characteristics of the soil and the material in whichit formed are identified for each soil series. A pedon, asmall three-dimensional area of soil, that is typical ofthe series in the survey area is described. The detaileddescription of each soil horizon follows standards inthe “Soil Survey Manual” (Soil Survey Division Staff,1993). Many of the technical terms used in thedescriptions are defined in “Keys to Soil Taxonomy”(Soil Survey Staff, 1998). Unless otherwise stated,colors in the descriptions are for moist soil. Followingthe pedon description is the range of importantcharacteristics of the soils in the series.

The map units on the soil maps in this surveyrepresent the soils or miscellaneous areas in thesurvey area. These soils or miscellaneous areas arelisted as individual components in the map unitdescription. The map unit descriptions in this section,along with the maps, can be used to determine thesuitability and potential of a unit for specific uses. Theyalso can be used to plan the management needed forthose uses. More information about each map unit isgiven under the headings “Use and Management ofthe Soils” and “Soil Properties.”

A map unit delineation on a soil map represents anarea dominated by one or more major kinds of soil ormiscellaneous areas. A map unit is identified andnamed according to the taxonomic classification of thedominant soils. Within a taxonomic class there areprecisely defined limits for the properties of the soils.On the landscape, however, the soils are naturalphenomena, and they have the characteristicvariability of all natural phenomena. Thus, the range ofsome observed properties may extend beyond thelimits defined for a taxonomic class. Areas of soils of asingle taxonomic class rarely, if ever, can be mappedwithout including areas of other taxonomic classes.Consequently, every map unit is made up of the soilsor miscellaneous areas for which it is named andsome minor components that belong to taxonomicclasses other than those of the major soils.

Most minor soils have properties similar to those of

the dominant soil or soils in the map unit, and thusthey do not affect use and management. These arecalled noncontrasting, or similar, components. Theymay or may not be mentioned in a particular map unitdescription. Other minor components, however, haveproperties and behavioral characteristics divergentenough to affect use or to require differentmanagement. These are called contrasting, ordissimilar, components. They generally are in smallareas and could not be mapped separately because ofthe scale used. Some small areas of stronglycontrasting soils or miscellaneous areas are identifiedby a special symbol on the maps. The contrastingcomponents are mentioned in the map unitdescriptions. A few areas of minor components maynot have been observed, and consequently they arenot mentioned in the descriptions, especially wherethe pattern was so complex that it was impractical tomake enough observations to identify all the soils andmiscellaneous areas on the landscape.

The presence of minor components in a map unit inno way diminishes the usefulness or accuracy of thedata. The objective of mapping is not to delineate puretaxonomic classes but rather to separate thelandscape into landforms or landform segments thathave similar use and management requirements. Thedelineation of such segments on the map providessufficient information for the development of resourceplans. If intensive use of small areas is planned,however, onsite investigation is needed to define andlocate the soils and miscellaneous areas.

An identifying symbol precedes the map unit namein the map unit descriptions. Each description includesgeneral facts about the unit and gives some of the soilproperties and qualities that may affect planning forspecific uses.

Soils that have profiles that are almost alike makeup a soil series. Except for differences in texture of thesurface layer, all the soils of a series have majorhorizons that are similar in composition, thickness,and arrangement.

Soils of one series can differ in texture of thesurface layer, slope, stoniness, salinity, degree oferosion, and other characteristics that affect their use.On the basis of such differences, a soil series is

Soil Series and Detailed Soil Map Units

26 Soil Survey of

divided into soil phases. Most of the areas shown onthe soil maps are phases of soil series. The name of asoil phase commonly indicates a feature that affectsuse or management. For example, Hickory silt loam,10 to 18 percent slopes, eroded, is a phase of theHickory series.

A map unit is named for the component orcomponents that make up a dominant percentage ofthe map unit. Many map units consist of one dominantcomponent. These map units are consociations. Sablesilty clay loam, 0 to 2 percent slopes, is an example.

Some map units are made up of two or moredominant components. These map units arecomplexes. A complex consists of two or morecomponents in such an intricate pattern or in suchsmall areas that they cannot be shown separately onthe maps. Attempting to delineate the individualcomponents of a complex would result in excessiveclutter that could make the map illegible. The patternand proportion of the components in a complex aresomewhat similar in all areas. Marseilles-Hickory siltloams, 35 to 60 percent slopes, is an example.

This survey includes miscellaneous areas. Suchareas have little or no soil material and support little orno vegetation. The map unit Pits, gravel, is anexample.

Table 5 gives the acreage and proportionate extentof each map unit. Other tables (see Contents) giveproperties of the soils and the limitations, capabilities,and potentials for many uses. The Glossary definesmany of the terms used in describing the soils ormiscellaneous areas.

Ambraw Series

Taxonomic classification: Fine-loamy, mixed,superactive, mesic Fluvaquentic Endoaquolls

Typical Pedon

Ambraw clay loam, 0 to 2 percent slopes, rarelyflooded; 2,400 feet north and 160 feet east of thesouthwest corner of sec. 11, T. 19 N., R. 3 E.; inWhiteside County, Illinois; USGS Erie Northwesttopographic quadrangle; lat. 41 degrees 38 minutes 57seconds N. and long. 90 degrees 07 minutes 54seconds W., NAD 27:

Ap—0 to 10 inches; black (10YR 2/1) clay loam, verydark grayish brown (10YR 3/2) dry; weak finesubangular blocky structure parting to weak finegranular; friable; slightly acid; abrupt smoothboundary.

A—10 to 20 inches; very dark gray (10YR 3/1) clayloam, dark grayish brown (10YR 4/2) dry; weak

fine subangular blocky structure parting to weakfine granular; friable; many distinct black (10YR2/1) organic coatings on faces of peds; few fineprominent yellowish brown (10YR 5/6) iron oxidemasses in the matrix; neutral; clear smoothboundary.

Bg1—20 to 27 inches; dark gray (10YR 4/1) clay loam;moderate medium and fine subangular blockystructure; friable; many distinct very dark gray(10YR 3/1) organic coatings on faces of peds; fewfine concretions of iron oxide throughout thematrix; common fine prominent strong brown(7.5YR 4/6) iron oxide masses in the matrix;neutral; clear smooth boundary.

Bg2—27 to 32 inches; dark gray (10YR 4/1) clay loam;weak medium prismatic structure; friable; few faintconcretions of iron oxide throughout the matrix;many medium prominent yellowish brown (10YR5/6) and few fine prominent strong brown (7.5YR4/6) iron oxide masses in the matrix; slightly acid;clear smooth boundary.

Bg3—32 to 36 inches; gray (5Y 5/1) clay loam; weakmedium subangular blocky structure; friable; verydark gray (10YR 3/1) krotovina 1 inch wide at adepth of 34 to 35 inches; few fine concretions ofiron oxide throughout the matrix; many mediumprominent yellowish brown (10YR 5/6) and fewfine prominent strong brown (7.5YR 4/6) iron oxidemasses in the matrix; neutral; abrupt smoothboundary.

Bg4—36 to 45 inches; gray (5Y 5/1) clay loam withthin strata of gray (10YR 5/1) sandy clay loam;weak medium subangular blocky structure; friable;few fine soft masses of iron oxide throughout thematrix; few fine prominent brown (7.5YR 5/4) andcommon fine prominent yellowish brown (10YR5/6) iron oxide masses in the matrix; slightly acid;gradual smooth boundary.

Cg—45 to 60 inches; stratified grayish brown (2.5Y5/2) clay loam, very dark grayish brown (2.5Y 3/2)sandy clay loam, and brown (10YR 5/3) loamysand; massive; friable; few fine prominentyellowish brown (10YR 5/6) iron oxide masses inthe matrix; neutral.

Range in Characteristics

Thickness of the mollic epipedon: 10 to 24 inchesDepth to free carbonates: More than 50 inchesThickness of the solum: 40 to 60 inches

Ap or A horizon:Hue—10YR, 2.5Y, or NValue—2 or 3Chroma—0 to 2

Rock Island County, Illinois 27

Texture—clay loam, loam, sandy loam, sandy clayloam, or silty clay loam

Bg horizon:Hue—10YR, 2.5Y, 5Y, or NValue—4 to 6Chroma—0 to 2Texture—loam, clay loam, sandy clay loam, sandy

loam, or silt loam

Cg horizon:Hue—10YR, 2.5Y, or 5YValue—4 to 6Chroma—1 to 4Texture—stratified sand, loamy sand, sandy loam,

loam, silt loam, and clay loam

8302A—Ambraw loam, 0 to 2 percentslopes, occasionally flooded

Setting

Landform: Flood plains

Composition

Ambraw and similar soils: 95 percentDissimilar soils: 5 percent

Minor Components

Similar soils:• Soils that contain more clay in the lower part• Soils that have a thicker surface layer

Dissimilar soils:• Moderately well drained soils on footslopes

Properties and Qualities of the Ambraw Soil

Parent material: AlluviumDrainage class: Poorly drainedSlowest permeability within a depth of 40 inches:

Moderately slowPermeability below a depth of 60 inches: Moderately

slow or moderateDepth to restrictive feature: More than 80 inchesAvailable water capacity to a depth of 60 inches: About

9.4 inchesContent of organic matter in the surface layer: 2 to 3

percentShrink-swell potential: ModerateDepth and months of the highest apparent seasonal

high water table: At the surface, January to MayPonding depth: 0.2 foot during wet periodsFrequency and most likely period of flooding:

Occasional, November to JunePotential for frost action: High

Hazard of corrosion: High for steel and moderate forconcrete

Surface runoff class: NegligibleSusceptibility to water erosion: SlightSusceptibility to wind erosion: Slight

Interpretive Groups

Land capability classification: 2wPrime farmland status: Prime farmland where drainedHydric soil status: Hydric

Atlas Series

Taxonomic classification: Fine, smectitic, mesic AericChromic Vertic Epiaqualfs

Map units in which this series occurs: 946D3, 946F3

Typical Pedon

Atlas silt loam, 5 to 10 percent slopes, eroded, at anelevation of 665 feet; 1,200 feet west and 50 feet southof the northeast corner of sec. 7, T. 1 N., R. 6 W.; inWarren County, Illinois; USGS Coatsburg topographicquadrangle; lat. 40 degrees 05 minutes 40 seconds N.and long. 91 degrees 07 minutes 52 seconds W., NAD27:

Ap—0 to 7 inches; dark grayish brown (10YR 4/2) siltloam, light brownish gray (10YR 6/2) dry; weakfine granular structure; friable; common very fineand fine roots; common medium prominent brown(7.5YR 5/8) and few fine distinct yellowish brown(10YR 5/6) masses of iron throughout; few fineprominent black (2.5Y 2/1) masses of iron andmanganese throughout; slightly acid; clear smoothboundary.

BE—7 to 13 inches; brown (10YR 5/3) silty clay loam,light brownish gray (10YR 6/2) dry; weak mediumsubangular blocky structure; friable; common fineroots; few fine distinct light brownish gray (10YR6/2) clay depletions throughout; few fine distinctyellowish brown (10YR 5/6) masses of ironthroughout; slightly acid; clear wavy boundary.

2Btg1—13 to 26 inches; dark gray (10YR 4/1) siltyclay loam; moderate thick platy structure parting toweak fine subangular blocky; firm; common fineand few medium roots; common distinct very darkgray (10YR 3/1) organo-clay films on faces ofpeds and in pores; few fine prominent yellowishbrown (10YR 5/6) masses of iron and few finedistinct white (10YR 8/1) masses of baritethroughout; moderately acid; clear wavy boundary.

2Btg2—26 to 37 inches; 87 percent dark gray (10YR4/1) and 10 percent gray (10YR 5/1) silty clay;

28 Soil Survey of

weak medium prismatic structure; firm; commonfine and medium roots; few distinct very dark gray(10YR 3/1) organo-clay films on faces of peds andin pores; common fine prominent yellowish brown(10YR 5/6) masses of iron and few fine distinctwhite (10YR 8/1) masses of barite throughout;1 percent rounded gravel and 1 percentsubangular limestone-cherty gravel; neutral; clearwavy boundary.

2Btg3—37 to 47 inches; gray (2.5Y 5/1) silty clay;weak coarse prismatic structure; firm; commonfine roots; few distinct very dark gray (10YR 3/1)organo-clay films on faces of peds and in pores;few fine prominent yellowish brown (10YR 5/6)masses of iron throughout; few fine faint gray(10YR 6/1) iron depletions and few fine distinctwhite (10YR 8/1) masses of barite throughout;1 percent angular gravel; neutral; clear wavyboundary.

2Btg4—47 to 61 inches; gray (2.5Y 5/1) clay loam;weak coarse prismatic structure; firm; commonvery fine roots; few distinct very dark gray (10YR3/1) organo-clay films on faces of peds and inpores; few fine distinct black (2.5Y 2/1) masses ofiron and manganese and few fine distinct white(10YR 8/1) barite crystals throughout; 1 percentlimestone-cherty gravel and 1 percent roundedigneous-granite gravel; neutral; clear wavyboundary.

2BCg—61 to 80 inches; light brownish gray (2.5Y 6/2)clay loam; weak coarse prismatic structure; firm;few fine distinct yellowish brown (10YR 5/6) andcommon medium prominent brownish yellow(10YR 6/8) masses of iron throughout; 2 percentlimestone-cherty gravel; neutral.

Range in Characteristics

Depth to the base of the argillic horizon: More than 42inches

Ap or A horizon:Hue—10YRValue—2 to 5Chroma—1 to 4Texture—silt loam, loam, silty clay loam, or clay

loam

E or BE horizon:Hue—10YRValue—4 or 5Chroma—1 to 4Texture—silt loam or silty clay loam

Bt, Btg, or 2Btg horizon:Hue—10YR, 2.5Y, 5Y, or NValue—4 to 6

Chroma—0 to 2Texture—clay loam, clay, silty clay loam, or silty

clayContent of rock fragments—0 to 5 percent

2Cg horizon (if it occurs):Hue—10YR, 7.5YR, 2.5Y, 5Y, or NValue—4 to 6Chroma—0 to 6Texture—silty clay loam, clay loam, or loamContent of rock fragments—2 to 15 percent

Atterberry Series

Taxonomic classification: Fine-silty, mixed,superactive, mesic Udollic Endoaqualfs

Typical Pedon (Official Series Description)

Atterberry silt loam, 0 to 2 percent slopes; 1,650 feetnorth and 1,120 feet east of the southwest corner ofsec. 34, T. 16 N., R. 9 E.; in Bureau County, Illinois;USGS Princeton South topographic quadrangle; lat. 41degrees 19 minutes 30 seconds N. and long. 89degrees 26 minutes 47 seconds W., NAD 27:

Ap—0 to 9 inches; very dark grayish brown (10YR 3/2)silt loam, brown (10YR 5/3) dry; moderate finegranular structure; friable; few fine roots; neutral;abrupt smooth boundary.

E—9 to 13 inches; light brownish gray (10YR 6/2) siltloam; moderate thin platy structure; friable; fewfine roots; common fine faint grayish brown (10YR5/2) redoximorphic depletions; slightly acid; clearsmooth boundary.

BE—13 to 17 inches; brown (10YR 5/3) silt loam;moderate medium platy structure parting tomoderate very fine subangular blocky; friable; fewfine roots; common faint brown (10YR 4/3) clayfilms on faces of peds and common distinct lightgray (10YR 7/2) (dry) redoximorphic claydepletions on faces of peds; few fine dark brown(7.5YR 3/2) concretions of iron and manganeseoxide; few fine faint grayish brown (10YR 5/2) irondepletions; slightly acid; clear smooth boundary.

Bt—17 to 24 inches; brown (10YR 5/3) silty clay loam;moderate fine subangular blocky structure; firm;few fine roots; many faint dark grayish brown(10YR 4/2) clay films and common faint light gray(10YR 7/2) (dry) redoximorphic clay depletions onfaces of peds; common fine rounded dark brown(7.5YR 3/2) concretions of iron and manganeseoxide; common fine faint grayish brown (10YR 5/2)iron depletions and common fine distinct yellowishbrown (10YR 5/6) iron concentrations; stronglyacid; clear smooth boundary.

Rock Island County, Illinois 29

Btg1—24 to 33 inches; grayish brown (2.5Y 5/2) siltyclay loam; moderate medium subangular blockystructure; friable; few fine roots; many distinctgrayish brown (10YR 5/2) clay films and fewdistinct light gray (10YR 7/2) (dry) redoximorphicclay depletions on faces of peds; common finerounded dark brown (7.5YR 3/2) concretions ofiron and manganese oxide; common fine faint lightbrownish gray (2.5Y 6/2) iron depletions andcommon fine distinct yellowish brown (10YR 5/6)iron concentrations; strongly acid; clear smoothboundary.

Btg2—33 to 40 inches; light brownish gray (2.5Y 6/2)silty clay loam; moderate medium prismaticstructure parting to moderate medium subangularblocky; friable; few fine roots; common distinctgrayish brown (10YR 5/2) clay films and fewdistinct light gray (10YR 7/2) (dry) redoximorphicclay depletions on faces of peds; many prominentvery dark grayish brown (10YR 3/2) clay filmslining pores; common fine prominent rounded darkbrown (7.5YR 3/2) concretions of iron andmanganese oxide; many fine prominent yellowishbrown (10YR 5/6) iron concentrations; stronglyacid; clear smooth boundary.

Btg3—40 to 48 inches; light brownish gray (2.5Y 6/2)silty clay loam; moderate coarse prismaticstructure; friable; few fine roots; common distinctgrayish brown (10YR 5/2) clay films on faces ofpeds; many prominent very dark grayish brown(10YR 3/2) clay films lining pores; many fineprominent yellowish brown (10YR 5/6) ironconcentrations; strongly acid; clear smoothboundary.

BCg—48 to 55 inches; light brownish gray (2.5Y 6/2)silt loam; weak coarse prismatic structure; friable;common distinct grayish brown (10YR 5/2) clayfilms on faces of peds; many prominent very darkgrayish brown (10YR 3/2) clay films lining pores;many medium prominent yellowish brown (10YR5/6) iron concentrations; moderately acid; clearsmooth boundary.

Cg—55 to 60 inches; light brownish gray (2.5Y 6/2) siltloam; massive; friable; many medium prominentyellowish brown (10YR 5/6) iron concentrations;slightly acid.

Range in Characteristics

Thickness of the solum: 42 to 72 inches

Ap or A horizon:Value—2 or 3Chroma—1 or 2Reaction—moderately acid to neutral

E horizon:Value—4 to 6Chroma—1 or 2Reaction—strongly acid to neutral

Bt or Btg horizon:Hue—10YR, 2.5Y, or 5YValue—4 to 6Chroma—2 to 4Texture—silty clay loam or silt loamReaction—strongly acid to neutral

C or Cg horizon:Hue—10YR, 2.5Y, or 5YValue—4 to 6Chroma—1 to 4Reaction—moderately acid to slightly alkaline

61A—Atterberry silt loam, 0 to 2 percentslopes

Setting

Landform: Ground morainesPosition on the landform: Summits

Composition

Atterberry and similar soils: 98 percentDissimilar soils: 2 percent

Minor ComponentsSimilar soils:• Soils that have more clay in the subsoil• Eroded soils that have slopes of 2 to 5 percent; nearthe head of drainageways

Dissimilar soils:• The well drained Fayette soils on shoulders• The well drained Rozetta soils on summits• The poorly drained Sable soils in depressions

Properties and Qualities of the Atterberry Soil

Parent material: LoessDrainage class: Somewhat poorly drainedSlowest permeability within a depth of 40 inches:

ModeratePermeability below a depth of 60 inches: ModerateDepth to restrictive feature: More than 80 inchesAvailable water capacity to a depth of 60 inches: About

11.7 inchesContent of organic matter in the surface layer: 1.5 to

3.5 percentShrink-swell potential: ModerateDepth and months of the highest apparent seasonal

high water table: 0.5 foot, January to MayFlooding: None

30 Soil Survey of

Accelerated erosion: None or slightPotential for frost action: HighHazard of corrosion: High for steel and moderate for

concreteSurface runoff class: LowSusceptibility to water erosion: SlightSusceptibility to wind erosion: Slight

Interpretive Groups

Land capability classification: 1Prime farmland status: Prime farmland where drainedHydric soil status: Not hydric

Biggsville Series

Taxonomic classification: Fine-silty, mixed,superactive, mesic Typic Hapludolls

Typical Pedon (Official Series Description)

Biggsville silt loam, 0 to 2 percent slopes, at anelevation of 630 feet; 1,520 feet west and 200 feetsouth of the northeast corner of sec. 30, T. 19 N., R. 3E.; in Rock Island County, Illinois; USGS Hillsdaletopographic quadrangle; lat. 41 degrees 36 minutes 40seconds N. and long. 90 degrees 12 minutes 00seconds W., NAD 27:

Ap—0 to 8 inches; very dark gray (10YR 3/1) silt loam,grayish brown (10YR 5/2) dry; moderate very fineand fine granular structure; friable; common fineroots; neutral; abrupt smooth boundary.

AB—8 to 16 inches; very dark grayish brown (10YR3/2) and brown (10YR 4/3) silt loam, grayishbrown (10YR 5/2) dry; moderate mediumsubangular blocky structure parting to moderatefine granular; friable; few fine roots; neutral;gradual smooth boundary.

Bw1—16 to 32 inches; brown (10YR 4/3) and darkyellowish brown (10YR 4/4) silt loam; moderatemedium prismatic structure parting to moderatemedium subangular blocky; friable; few fine roots;few faint very dark grayish brown (10YR 3/2)organic coatings on faces of peds; slightly acid;abrupt smooth boundary.

Bw2—32 to 47 inches; brown (10YR 4/3) silt loam;moderate medium prismatic structure; friable;common medium distinct brown (7.5YR 4/4) andyellowish brown (10YR 5/6) masses of iron withinpeds; common medium distinct grayish brown(10YR 5/2) iron depletions within peds; few fineblack (7.5YR 2.5/1) iron and manganese oxidestains; slightly acid; gradual smooth boundary.

Cg—47 to 80 inches; grayish brown (10YR 5/2), brown(7.5YR 4/4), and yellowish brown (10YR 5/6) silt

loam; massive; friable; few fine black (7.5YR 2.5/1)iron and manganese oxide stains; slightly acid.

Range in Characteristics

Thickness of the mollic epipedon: 10 to 20 inchesDepth to the base of the cambic horizon: More than 42

inches

Ap or A horizon:Value—2 or 3Chroma—1 to 3Reaction—moderately acid to moderately alkaline

Bw or BC horizon:Hue—7.5YR or 10YRValue—3 to 5Chroma—3 to 6Reaction—moderately acid to neutral

C or Cg horizon:Hue—7.5YR, 10YR, or 2.5YValue—4 to 6Chroma—2 to 6Reaction—slightly acid to moderately alkaline

671A—Biggsville silt loam, 0 to 2 percentslopes

Setting

Landform: Ground morainesPosition on the landform: Summits

Composition

Biggsville and similar soils: 95 percentDissimilar soils: 5 percent

Minor Components

Similar soils:• Soils that do not have a seasonal high water tablewithin a depth of 6 feet• Soils that have a surface layer more than 24 inchesthick• Soils that are underlain by sand within a depth of 60inches

Dissimilar soils:• The somewhat poorly drained Joy soils on summits

Properties and Qualities of the Biggsville Soil

Parent material: LoessDrainage class: Well drainedSlowest permeability within a depth of 40 inches:

ModeratePermeability below a depth of 60 inches: ModerateDepth to restrictive feature: More than 80 inches

Rock Island County, Illinois 31

Available water capacity to a depth of 60 inches: About12.8 inches

Content of organic matter in the surface layer: 3 to 5percent

Shrink-swell potential: LowDepth and months of the highest apparent seasonal

high water table: 4 feet, February to AprilFlooding: NoneAccelerated erosion: None or slightPotential for frost action: HighHazard of corrosion: Low for steel and moderate for

concreteSurface runoff class: LowSusceptibility to water erosion: SlightSusceptibility to wind erosion: Slight

Interpretive Groups

Land capability classification: 1Prime farmland status: Prime farmlandHydric soil status: Not hydric

671B—Biggsville silt loam, 2 to 5 percentslopes

Setting

Landform: Ground morainesPosition on the landform: Shoulders

Composition

Biggsville and similar soils: 96 percentDissimilar soils: 4 percent

Minor Components

Similar soils:• Soils that do not have a seasonal high water tablewithin a depth of 6 feet• Soils that have a surface layer more than 24 inchesthick• Soils that are underlain by sand within a depth of 60inches

Dissimilar soils:• The somewhat poorly drained Joy soils on summits• The poorly drained Denny soils in depressions

Properties and Qualities of the Biggsville Soil

Parent material: LoessDrainage class: Well drainedSlowest permeability within a depth of 40 inches:

ModeratePermeability below a depth of 60 inches: ModerateDepth to restrictive feature: More than 80 inchesAvailable water capacity to a depth of 60 inches: About

12.8 inches

Content of organic matter in the surface layer: 3 to 5percent

Shrink-swell potential: LowDepth and months of the highest apparent seasonal

high water table: 4 feet, February to AprilFlooding: NonePotential for frost action: HighHazard of corrosion: Low for steel and moderate for

concreteSurface runoff class: LowSusceptibility to water erosion: SlightSusceptibility to wind erosion: Slight

Interpretive Groups

Land capability classification: 2ePrime farmland status: Prime farmlandHydric soil status: Not hydric

Birds Series

Taxonomic classification: Fine-silty, mixed,superactive, nonacid, mesic Typic Fluvaquents

Typical Pedon

Birds silt loam, undrained, 0 to 2 percent slopes,frequently flooded; 2,050 feet north and 110 feet westof the southeast corner of sec. 36, T. 5 N., R. 4 W.; inMcDonough County, Illinois; USGS Fandontopographic quadrangle; lat. 40 degrees 22 minutes 26seconds N. and long. 90 degrees 47 minutes 30seconds W., NAD 27:

Ap—0 to 9 inches; dark gray (10YR 4/1