8 v_ol_um_e_l ~.. . Geology

SUGAR-PECATONICA AREA ASSESSMENT

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VOLUME 1: GEOLOGY

Illinois Department ofNatural Resources Office of Scientific Research and Analysis State Geological Survey Division 6I5 East Peabody Drive Champaign, 61820 (217) 333-4747

1998

Rod R Blagojevich, Governor State ofIllinois

Joel Brunsvold, Director Illinois Department ofNatural Resources One Natural Resources Way Springfield, IL 62702

300 Printed by the authority ofthe State ofnlinois Other CTAP Publications

The Sugar-Pecatonica Rivers Basin: An Inventory ofthe 's Resources - 22-page color booklet

Descriptive inventories and 5-volume technical reports are also available for the following areas: Rock River Embarras River Cache River Upper Des Plaines River Mackinaw River Illinois River Bluffs Illinois Headwaters Spoon River Illinois Big Rivers Driftless Area Fox River Lower Rock River Kankakee River Kishwaukee River

Also available: Illinois Land Cover, An Atlas, plus CD-ROM Inventory ofEcologically Resource-Rich Areas in Illinois Annual Report 1997, Illinois EcoWatch Illinois Geographic Information System, CD-ROM ofdigital geospatial data

All CTAP and Ecosystems Program documents are available from the DNR Clearinghouse at (217) 782-7498 or TDD (217) 782-9175. Selected publications are also available on the World Wide Web at http://dnr.state.il.us/ctap/ctaphome.htm, or http://dnr.state.il.us/c2000/manage/partner.htm, as well as on the EcoForum Bulletin Board at 1 (800) 528-5486 or (217) 782-8447.

For more information about CTAP, call (217) 524-0500 or e-mail [email protected]; for information on the Ecosystems Program call (217) 782-7940 or e-mail at [email protected].

The Illinois Department ofNatural Resources does not discriminate based upon race, color, national origin, age, sex, religion or disability in its programs, services, activities and facilities. Ifyou believe that you have been discriminated against or ifyou wish additional information, please contact the Department at (217) 785-0067 or the U.S. Department ofthe Interior Office ofEqual Employment, Washington, D.C. 20240. About This Report

The Sugar-Pecatonica Area Assessment examines an area in north along the WisconsinlIllinois border. Because significant natural community and species diversity is found in one subbasin along the Sugar and Pecatonica rivers, it has been designated a state Resource Rich Area. 1

This report is part ofa series of reports on areas ofIllinois where a public-private partnership has been formed to protect natural resources. These assessments provide information on the natural and human resources ofthe areas as a basis for managing and improving their ecosystems. The determination of resource rich areas and development of ecosystem-based information and management programs in Illinois are the result ofthree processes - the Critical Trends Assessment Program, the Conservation Congress, and the Water Resources and Land Use Priorities Task Force.

Background

The Critical Trends Assessment Program (CTAP) documents changes in ecological conditions. In 1994, using existing information, the program provided a baseline of ecological conditions1 Three conclusions were drawn from the baseline investigation:

1. the emission and discharge of regulated pollutants over the past 20 years has declined, in some cases dramatically, 2. existing data suggest that the condition of natural ecosystems in Illinois is rapidly declining as a result offragmentation and continued stress, and 3. data designed to monitor compliance with environmental regulations or the status of individual species are not sufficient to assess ecosystem health statewide.

Based on these findings, CTAP has begun to develop methods to systematically monitor ecological conditions and provide information for ecosystem-based management. Five components make up this effort:

I. identify resource rich areas, 2. conduct regional assessments, 3. publish an atlas and inventory ofIllinois landcover, 4. train volunteers to collect ecological indicator data, and 5. develop an educational science curriculum which incorporates data collection

I See Inventory ofResource Rich Areas in Illinois: An Evaluation ofEcological Resources. 2 See The Changing Illinois Environment: Critical Trends, sull1Ill3IY report and volumes 1-7.

III At the same time that CTAP was publishing its baseline findings, the Illinois Conservation Congress and the Water Resources and Land Use Priorities Task Force were presenting their respective findings. These groups agreed with the CTAP conclusion that the state's ecosystems were declining. Better stewardship was needed, and they determined that a voluntary, incentive-based, grassroots approach would be the most appropriate, one that recognized the inter-relatedness ofeconomic development and natural resource protection and enhancement.

From the three initiatives was born Conservation 2000, a six-year program to begin reversing ecosystem degradation, primarily through the Ecosystems Program, a cooperative process of public-private partnerships that are intended to merge natural resource stewardship with economic and recreational development. To achieve this goal, the program provides financial incentives and technical assistance to private landowners. The Rock River and Cache River were designated as the first Ecosystem Partnership areas.

At the same time, CTAP identified 30 Resource Rich Areas (RRAs) throughout the state. In RRAs and other areas where Ecosystem Partnerships have been formed, CTAP is providing an assessment ofthe area, drawing from ecological and socio-economic databases to give an overview ofthe region's resources - geologic, edaphic, hydrologic, biotic, and socio­ economic. Although several ofthe analyses are somewhat restricted by spatial and/or temporal limitations ofthe data, they help to identify information gaps and additional opportunities and constraints to establishing long-term monitoring programs in the partnership areas.

The Sugar-Pecatonica Area Assessment

The Sugar-Pecatonica Area Assessment encompasses approximately 796.3 square miles (509,675 acres) in north central Illinois along the /Illinois border. The area includes virtually all of Stephenson County, the northwestern half of Winnebago County, and very small portions ofCarroll, J0 Daviess, and Ogle counties. There are 21 subbasins along the Sugar and Pecatonica rivers, ofwhich one has been designated a "Resource Rich Area" because it contains significant natural community diversity. The Sugar-Pecatonica Rivers Ecosystem Partnership was subsequently formed around this core area ofhigh quality ecological resources.

This assessment is comprised offive volumes. In Volume 1, Geology discusses the geology, soils, and minerals in the assessment area. Volume 2, Water Resources, discusses the surface and groundwater resources and Volume 3, Living Resources, describes the natural vegetation communities and the fauna of the region. Volume 4 contains three parts: Part I, Socio-Economic Profile, discusses the demographics,

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Figure 2. Major drainage basins of Illinois and location of the Sugar-Pecatonica Assessment Area Apple :; River ~

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Subbasins in the Sugar-Pecatonica Assessment Area. Subbasin boundaries depicted are those I determined by the Illinois Environmental Protection Agency. infrastructure, and economy ofthe area, focusing on the two counties with the greatest amount ofland in the area - Stephenson and Winnebago; Part II, Environmental Quality, discusses air and water quality, and hazardous and toxic waste generation and management in the area; and Part III, Archaeological Resources, identifies and assesses the archaeological sites known in the area. Volume 5, Early Accounts ofthe Ecology of the Sugar-Pecatonica Area, describes the ecology ofthe area as recorded by historical writings of explorers, pioneers, early visitors and early historians.

VII

Contributors

Introduction: Influence ofGeology and Soil. . .. MyrnaM.Killey on Ecosystem Development and William W. Shilts

Part 1 : The Natural Geologic Setting BedrockGeology ...... C.PiusWeibel Glacial and Surficial Geology ...... MyrnaM. Killey with contributions by Lisa R. Smith and James C. Hester

Modern Soils and the Landscape-Influences on Habitat...... Michael L. Barnhardt and Agriculture with contributions by Lisa R. Smith and James C. Hester Landscape Features and Natural Areas with Geologic Features ...... Myrna M. Killey of Interest with contributions by Lisa R. Smith and James C. Hester LandCoverInventory...... Donald E. Luman with contributions by Lisa R. Smith and James C. Hester

Part 2 : Geology and Society Mineral Resources ...... VijuIpe with contributions by Lisa R. Smith and James C. Hester AquiferDelineation Ross D. Brower and RobertC. Vaiden Potential for Geologic Hazards Daniel C. Barnstable Potential for Contamination ofGroundwater Resources ...... Donald A. Keefer with contributions byLisaR..Smith and James C. Hester Regional Earthquake Activity...... Timothy H. Larson with contributions by Lisa R. Smith and James C. Hester Appendix A: Overview ofDatabases ...... LisaR. Smith Appendix B: Land Cover by Subbasin...... DonaldE.Luman

ix Table of Contents

Introduction: Influence of Geology and Soils on Ecosystem Development. . 1·

Part 1: The Natural Geologic Setting. . 7 Geology ...... 8 Glacial and Surficial Geology ...... 13 Modem Soils and the Landscape-Influences on Habitat and Agriculture . 20 Landscape Features and Natural Areas with Geologic Features of Interest . 29 Land Cover Inventory ...... 32

Part 2: Geology and Society 53 Mineral Resources ...... 54 Delineation . . . . . 60 Potential for Geologic Hazards. 66 Potential for Contamination of Groundwater Resources 66 Regional Earthquake Activity. . . . 72 Appendix A: Overview of Databases . 76 Appendix B: Land Cover by Subbasin. 79

List ofFigures Introduction: Influence of Geology and Soils on Ecosystem Development Figure 1. Sugar-Pecatonica Assessment Area ...... 5

Part 1: The Natural Geologic Setting Figure 2. Geologic Time Scale...... 8 Figure 3. Bedrock Geology ...... 9 Figure 4. Buried Bedrock Topography. II Figure 5. Glacial Geology...... 17 Figure 6. Thickness of Glacial Drift . . . . 18 Figure 7. Topography of the Land Surface. 21 Figure 8. Soil Associations ...... 22 Figure 9. Physiographic Divisions of Illinois. 30 Figure 10. Subbasins of the Sugar-Pecatonica Assessment Area 40 Figure 11. Principal Land Cover: Agricultural...... 41

x Figure 12. Comparison of Principal Land Cover for the State of lilinois and the Sugar-Pecatonica Assessment Area . 42 Figure 13. Agricultural Land Cover by Subbasin . 43 Figure 14. Principal Land Cover: Cropland. . . . 44 Figure 15. Principal Land Cover: Rural Grassland. 45 Figure 16. Principal Land Cover: Forest and Woodland. 46 Figure 17. Forest and Woodland Land Cover by Subbasin 47 Figure 18. Principal Land Cover: Wetland...... 48 Figure 19. Wetland Land Cover by Subbasin ...... 49 Figure 20. Principal Land Cover: Urban and Built-Up Land 50 Figure 21. Detail of Land Cover Around Freeport, lilinois 51 Figure 22. Urban and Built-Up Land Cover by Subbasin 52

Part 2: Geology and Society Figure 23. Active Quarries...... 55 Figure 24. Potential Mineral Resources ...... 56 Figure 25. Aquifer Sensitivity to Contamination by Pesticide Leaching 70 Figure 26. Earthquakes in the Vicinity of the Sugar-Pecatonica Assessment Area . 74

List of Tables Part 1: The Natural Geologic Setting Table I. Land Cover of the Sugar-Pecatonica Assessment Area...... 34 Table 2. Land Cover of Illinois...... 35 Table 3. Principal Land Cover of the Sugar-Pecatonica Assessment Area. 36

Part 2: Geology and Society Table 4. Mineral Producers in the Sugar-Pecatonica Assessment Area ...... 57

xi

Introduction: Influence of Geology and Soils on Ecosystem Development

Geology is . .. the original source ofinorganic chemical nutrientsfor the biosphere and provides the abiotic physical environment ofthe biosphere. Through knowledge ofrock type mineralogy, the geologist can predict the amount and variety oftoxic or beneficial inorganic chemical nutrients present. ...Geological processes modifying geologic materials create landforms that are commonly a basisfor land unit hierarchies. Geologists can increase understanding ofland unit hierarchies in ecosystem studies. ... Geologists can be critical players in understanding ecosystems.J

The 'Natural Divisions ofIllinois' is a classification ofthe natural envi­ ronments and biotic communities ofIllinois based on physiography, flora, andfauna. ... Factors considered in delimiting the 14 natural divisions are topography, soils, bedrock, glacial history, and the distribution of plants and animals.2

In the few areas of the earth that have not been modified by human settlement, the patterns of vegetation and the animals that interact with vegetation are directly influenced by geo­ logical factors. In fact, in undisturbed areas, surficial geology and to some extent bedrock geology can be mapped using inferences drawn from vegetation patterns observed on air photographs and satellite images and during field observations. For example, in the pris­ tine terrains of northern , ecosystem variations were used to infer and eventually map underlying geological conditions.

The geological characteristics that most influence ecosystem development are soil moisture and composition, topography (including slope angle, slope direction, and local drainage), and texture of the parent material. In some places, geological events such as earthquakes, glacial advances and retreats, and volcanic eruptions exert a strong control over the eco­ system. Even animal activities that are seemingly removed from geological control are influenced by geological factors such as availability of salt for migrating herds, availabil­ ity of suitable vegetation for food, or-in the case of carnivores-suitable colonies of prey that congregate near geologically controlled food sources.

I P. Hughes, A geologic response to the Seventh American Forest Congress and Round Tables: Environ­ mental Geology 28 (I) July 1996, p. 52-53.

2 Comprehensive Plan for the minois Nature Preserves System, Part 2, The Natural Divisions of minois, John E. Schwegman, principal author, 1984, minois Nature Preserves Commission, p. 3.

I In uninhabited areas of the glaciated North American , ridges of gravel () left behind by retreating served as transportation routes for early humans and animals alike. The ridges provided ease of footing, vantage points for hunters or the hunted, and protection from ravenous insects that prefer the calmer air of low-lying areas. Even in modern America, roads in New England are often constructed on these ridges. These examples clearly illustrate the dominant role local geologic factors can play in ecosystem development.

Before human settlement, a whole panoply of Illinois' ecological components was in equilibrium with the geology and of an area. The original ecological systems were closely attuned to the variety of near-surface conditions that are generated by the distribution of glacial deposits and by spatial variations in bedrock units.

The glacial (arc-shaped ridges) in the northeastern part of the state provided well-drained soils for forest growth and refuge for forest-dwelling animals. The low, flat are sites where shallow lakes were dammed between moraines and became poorly drained seas of herbaceous plants whose luxuriant growth provided the biomass for the thick organic-rich soils that support so much agriculture. Illinois' soils developed on or thick that are mixtures of crushed bedrock particles. These soil parent materials, formed and homogenized by the grinding action of glaciers, supply abundant nutrients vital to crops that are the agricultural basis of our society.

Where glaciers did not cover the terrain, the topography, soils, and vegetation differed significantly. The soils are either directly related to the composition of the immediately underlying bedrock from which they were formed by chemical and physical weathering, or were transported into the area by wind or running water. The contrasts in our ancient ecosystems can be imagined by observing the ways modern society has adjusted to the differences between the soils of the glaciated and unglaciated parts of the state: except on alluvial plains, crops are not a major source of income outside the large area of the state that was glaciated.

On our modern landscape, original ecosystems cannot be restored or maintained without respecting the geologic factors that generated the original complex plant and animal inter­ relations. For instance, attempting to reestablish a wetland consisting of acid loving plants that require periodic drying will not succeed in depressions actively fed by groundwater that passes through alkaline glacial . Likewise, reestablishing certain types of forest vegetation on an unstable terrain underlain by thick, easily erodible glacial loess is likely to fail.

Land on a high terrace ofthe Illinois River, about IOOfeet above the river channel, was purchasedfor wetlands restoration. The permanent water table was nine feet below the surface, and the sandy soils were highly permeable. Wetlands plants installed at the site died and were replaced naturally by upland plant species tolerant ofthe dry conditions. Had read­ ily available information on geology and hydrogeology ofthe area been taken into consideration, it would have clearly indicated that this site was

2 inappropriate as a potential wetlands compensation site. Given that the existence ofwetlands depends on hydrology, and hydrology depends on geologic and geomorphic factors, such information identifies areas most favorable for the occurrence ofwetlands or wetland mitigation. -Michael V. Miller, Illinois State Geological Survey

Hine's emerald dragonfly, afederally listed endangered species, is associ­ ated with seep areas that receive groundwaterflows from dolomitic limestone formations. The exact habitat requirements oflarvae and adults are still unclear.-lllinois Natural History Survey Annual Report, 1995-1996, p. 10

Notice that these two examples of the interrelationships between geology and ecosystem elements illustrate the four geologic factors considered by the Illinois Nature Preserves Commission (Schwegman 1984) in delimiting the 14 natural divisions of the state: topog­ raphy (high terrace of a river channel), soils (sandy permeable soils), bedrock (dolomitic limestone formations), and glacial history (the Illinois River channel's location and con­ figuration are due largely to the area's glacial history).

Topography influences the biota of Illinois by controlling the diversity of habitats: gener­ ally, the more rugged the topography, the greater the diversity of habitats. The type of bedrock is often reflected by a characteristic topography (for example, is typi­ cally hard and resistant, forming bluffs and ledges, whereas is soft and erodible, forming smooth slopes). Bedrock also exerts a control on plant life because of the thin soils that commonly are developed in it. A crucial factor in controlling soil type is the geologic material in which the soil developed (parent material); the diversity of soil par­ ent materials is partly responsible for the varied environments and biota within ecosys­ tems. Glacial history has played a major role in shaping the topography of the landscape: the subdued, irregular topography characteristic of recently glaciated areas generally is poorly drained, resulting in an abundance of aquatic habitats (Schwegman 1984).

Another interesting example ofthe interrelationships between geology and ecosystems is an observation made at certain landfills in which the water table assumes a mounded shape within the landfill. Cattails have been observed to grow where the water table is high, and cattails help clean up the water by taking some ofthe pollutants out ofthe leachate. -Keros Cartwright, Illinois State Geological Survey

The preceding examples all mention water as a crucial element. Water is also an inherent aspect of the four geologic factors used to delineate natural divisions: topography deter­ mines drainage, soil moisture is a function of soil texture, bedrock types determine resis­ tance to erosion, and glacial materials, which range from clayey glacial tills (see Glacial Geology section) to and gravels, vary widely in texture and moisture-holding capac­ ity and their ability to yield moisture to plants (Schwegman 1984).

***

3 The geologic foundation of the Sugar-Pecatonica Assessment Area is bedrock and glacially derived sediments that lie directly beneath the soils and modem sediments at the land sur­ face. The topography of the bedrock surface partly determined the type and distribution of the overlying glacial deposits. These sediments, in tum, store the area's groundwater re­ sources, form the parent materials of the region's rich soils, and playa role in the devel­ opment of wetland areas. and gravel deposited by streams of glacial meltwater supports an ongoing industry important to the region's economy. Together, these geologic factors govern the development of the entire range of plant and animal communities within the assessment area.

Part I of this volume, The Natural Geologic Setting, is organized "from the bottom up"-that is, we begin by describing the bedrock geology, then work our way upward from the bedrock surface and describe the sediments and features that stack on top ofeach other until they reach the landscape on which we live. This approach may seem counter­ intuitive to many readers: why don't we begin at the surface, with the geology we can see, and work our way downward? We believe the opposite strategy is a more logical and natural approach for two reasons: (I) it reflects the chronological order in which geologic materials were emplaced, and (2) it better describes how the bedrock geology and glacial deposits influence each other and how they combine to create the geologic template upon which life exists on the surface.

Part 2 of this volume, Geology and Society, examines the use of geologic resources within the assessment area and some of the impacts related to resource extraction. It also describes some of the dominant natural and society-induced geologic hazards that can occur in the assessment area.

The following discussions and accompanying maps are generalized for the entire Sugar­ Pecatonica Assessment Area (Figure I) and cannot be used for site-specific purposes. Users needing more detailed information should contact the authors at

lllinois State Geological Survey Natural Resources Building 615 East Peabody Drive Champaign, n... 61820-6964 217-333-4747

The maps reproduced in this volume are small-scale versions of preliminary work maps used by the authors in preparation of their sections. The level of detail in these maps is limited by the page size and type and quality of printing available for the reproduction of this report. In general, these maps are suitable for general planning and information pur­ poses. Higher-detail and higher-resolution maps suitable for more specific applications and assessments can be consulted or obtained by contacting the authors at the Illinois State Geological Survey.

The databases used in this report are discussed in Appendix A.

4 \V\

-w;r~1\ I " ~ WISCONSIN \ 'i'\ ILLINOIS ( II Apple 8 River .ummersBt J Davis .. : '-Durand .... \ \ yna ". Dakota 1 • Cedarville I Stockto 1 1 1 j \ 1 .1 I °1 I ~: / <.. , I !!:!I I I ~I~i I 0 1 ~ -'1 STEPHENSON CO. ______L_ _ _ WINNEBAGO CO. ______--.L ~--~~~T---~---' OGLE CO. ------I CARROLL CO. ).E' Lake iVer 1 lt ~ ~ " Garroll ~\'$ I 1L _ Forreston• III • o 5 10 15 20 ! assessment area -- assessment area Miles 0 boundary municipality I11III -- county boundary ! open water! N -- river or stream ~ - wide river I Figure 1. Sugar-Pecatonica Assessment Area The fact that Illinois is incOlporating geologic data into this report on the Sugar-Pecatonica Assessment Area, and into reports on other assessment areas in the state, is an appropriate recognition of the necessity of integrating geologic and biological data into efforts to preserve our natural heritage.

6 Part 1: The Natural Geologic Setting

Imagine that you are standing on the valley side overlooking the floodplain of the . In the distance you see broad, flat plains, gently rolling , and perhaps a tributary valley. Now imagine that 100 feet below that surface (more or less, depending on where you are standing), lies another landscape, complete with rolling hills, flat plains, and val­ leys. This is the bedrock surface. Every aspect of this surface-its shape, its composition, its stability or lack of it-and every aspect of the layers of glacial and surficial materials above the bedrock surface exerts some control on life at the surface of the earth. The nature of the geologic framework below us plays a key role in where flora and fauna prefer to grow, where streams flow, where humans build their homes, factories, and cities, and where land is set aside for parks and natural areas. Part 1 discusses the geologic framework of the Sugar-Pecatonica Assessment Area and, where possible, describes how the geology relates to ecosystems and habitat.

7 Bedrock Geology

Description of Materials

Bedrock beneath the Quaternary mantle of unconsolidated glacial material in the Sugar­ Pecatonica Assessment Area consists of sedimentary rocks of and Silurian age (Figure 2). Ordovician strata are dominated by three lithologies: the Ancell Group is dominantly sandstone, the -Platteville Group is dolomite, and the Maquoketa Group is shale. Silurian rocks are predominantly dolomite. Most of the bedrock subcrop (bed­ rock that occurs directly beneath glacial sediment) in the assessment area is of Ordovician age (Figure 3). The Ordovician Galena-Platteville Group dominates the bedrock surface in most of the assessment area. The outcrop pattern of the stratigraphic units is controlled by both topographic elevation and regional structural geology. The general orientation of strata in the assessment area is a gentle dip toward the southwest. Topographically, the bedrock surface is higher in the western part and lower in the eastern part of the area. As a result of the topography and the structure, the strata at the bedrock surface are generally older and lower in elevation to the east and younger and higher in elevation to the west. The

Millions Millions <:: of years 0 ~ of years Eon Era ago w w Period - Epoch ago Cenozoic Holocene '0" 66- Quaternary 0.01- N u 1.6­ e Mesozoic '0 Pliocene Q) 245­ N 5.3­ <:: c0 Miocene 23.7- .J:: Paleozoic Q) Tertiary UII ocene "­'" 0 Eocene 36.6­ 570-\ Paleocene 57.8- Late 66.4- ,, Cretaceous 900­ , '5 144 ­ .11 , N 0 , 0 N Middle

8 ! 1 -...!.l

o 5 10 15 20 I I I Miles Silurian (undiff.l Ordovician (Groups) Cambrian (undiff.) c::::::::J I11III Maquoketa ----t-- anticline assessment area boundary I ~illffl Galena-Platteville ----t- syncline - fault zone - 1 ~ Ancell

Figure 3. Bedrock Geology (modified after Willman and others 1967; Kolata and Buschbach 1976) \~

---- OC( ..... ···L--.. ··

DRIFTLESS AREA

Elevations are feet above mean sea level o 5 10 15 20 I CJ grealer Ihan 1000 80010850 _ 60010650 Miles CJ 95010 1000 75010800 _ 55010600 • • ... buried valley axes CJ 90010950 70010750 _ 50010550 ~t assessment area boundary CJ 85010900 _ 65010700 _ less than 500 Figure 4. Buried Bedrock Topography (modified after Herzog and others 1994) Ordovician Ancell Group is restricted to lower parts of bedrock valleys, but covers larger areas to the east. The Silurian rocks that overlie Ordovician strata are restricted to higher elevations at the western and southern edges of the assessment area.

The southernmost part of the assessment area includes a small portion of the Plum River Fault Zone (Kolata and Buschbach 1976). Along this structure, the strata south of the fault zone have moved upward relative to strata on the north side. The Uptons Syncline is a shallow fold that parallels the Plum River Fault Zone. Another small fold, the Pecatonica Anticline (Buschbach and Bond 1974), occurs in the southeast part of.the assessment area.

Bedrock Topography

The top of the bedrock in the Sugar-Pecatonica Assessment Area has a complex topography of buried valleys, lowlands, and uplands (Figure 4). Buried bedrock valleys generally con­ tain coarse grained sediments (sands and gravels) that form important, productive (Horberg 1945). The buried bedrock surface was originally shaped by a long period of erosion by regional fluvial drainage systems during the Tertiary Period. This surface proba­ bly was substantially modified during the early and middle Pleistocene Epoch (Kempton and others 1991). The buried Pecatonica Bedrock Valley (Horberg 1950) traverses most of the assessment area. Unlike most buried bedrock valleys, the course of this one is super­ imposed by the modern Pecatonica River. The buried bedrock valley probably formed prior to the Pleistocene glaciation and appears to have maintained its general drainage path after the glaciers receded. The buried Pecatonica Bedrock Valley was part of a river system that drained into the buried Rock Bedrock Valley, a precursor to the modern Rock River, located to the east of the assessment area. The modern Pecatonica River and some of its tributaries are eroding into bedrock (Ordovician Ancell sandstone and Galena­ Platteville dolomite) in numerous areas, both in Winnebago and Stephenson Counties.

10 References

Buschbach, T.e., and D.e. Bond, 1974, Underground Storage of in llIinois­ 1967: llIinois State Geological Survey, Illinois 86, 54 p.

Herzog, B.L., BJ. Stiff, e.A. Chenoweth, K.L. Warner, J.B. Sieverling, and C. Avery, 1994, Buried Bedrock Surface of Illinois: Illinois State Geological Survey Illinois Map 5.

Horberg, L., 1945, A major buried valley in east-central Illinois and its regional relationships: Journal of Geology, v. 53, no. 5, p. 349-359.

Horberg, L., 1950, Bedrock Topography of Illinois: Illinois State Geological Survey Bulletin 73, 111 p.

Kempton, J.P., W.H. Johnson, P.C. Heigold, and K. Cartwright, 1991, Mahomet bedrock valley in east-centrallllinois-Topography, glacial drift stratigraphy and hydrogeology, in W.N. Melhorn and J. P. Kempton, eds., Geology and Hydrogeology of the Teays­ Mahomet Bedrock Valley System: Geological Society of America Special Paper 258, p.91-124.

Kolata, D.R., and T.e. Buschbach, 1976, Plum River Fault Zone of : Illinois State Geological Survey Circular 491,20 p.

Palmer, A.R., 1983, The decade of American geology-1983 geologic time scale: Geology, vol. 11, p. 503-504.

Willman, H.B., J.C. Frye, J.A. Simon, K.E. Clegg, C. Collinson, J.A. Lineback, and T.C. Buschbach, 1967, Geologic Map of Illinois: Illinois State Geological Survey, 1:500,OOO-scale map.

12 Glacial and Surficial Geology

Description of Materials

Most of the unlithified sediments that overlie the bedrock were deposited by continental glaciers that advanced across the Sugar-Pecatonica Assessment Area during the Pleisto­ cene Epoch, or Great . Till (sometimes called diamicton by geologists) is the major type of glacial sediment found in the region; less abundant glacial deposits include lacustrine (lake) sediments, outwash (sand and gravel), and organic-rich debris (peat, for example). Overlying the deposits of glacial origin is a windblown silt, or loess (pro­ nounced "Iuss"), of late glacial and post-glacial age. Collectively, glacial sediments are called glacial drift. Knowledge of these deposits is especially important because they strongly influence land use, ecosystem development, landscape processes that can affect ecosystems (see also Modem Soils and the Landscape section below), and the effects of geologic hazards.

Till is a mixture of all sizes of rocks and ground-up rock debris, ranging from the smallest clay particles to the largest boulders. Most till is a compact mixture of clay, silt, and sand particles that provides the matrix that surrounds and supports larger grains, such as pebbles, cobbles, and boulders. Some till was deposited across the pre-existing landscape at the base of the as it moved forward; other till is sediment that flowed as a muddy mass of material off the front of the melting or through crevasses (cracks) that devel­ oped within the ice. Each layer (or bed) of till may represent a particular glacial advance that can be recognized over large . These layers help identify major groups of sedi­ ment associated with particular glacial episodes.

When exposed in stream banks, the dense, compact till can be involved in slumping and minor landslides. During the infrequent earthquakes experienced in the area, however, till is less likely to enhance seismic energy than is the loose, water-saturated sediments found along river floodplains.

Lacustrine (lake) deposits are generally fine grained sediments such as silt and clay depos­ ited in temporary lakes that commonly formed along the margin of the ice as it melted. These sediments commonly are poorly drained and may cause water problems in construc­ tion projects.

Outwash is sand and gravel that literally "washed out" from the ice in meltwater streams that flowed along and away from the margin of a glacier. In the Sugar-Pecatonica Assess­ ment Area, outwash is found in (I) stream valleys that served as meltwater outlets in front of, or beneath, the glacier, and (2) isolated hillocks and ridges formed on the landscape where meltwater carrying rock debris plunged through crevasses in the ice. Where exten­ sive layers of outwash are associated with particular tills, the identification of the tills in

13 drillholes helps geologists predict the occurrence of major bodies of outwash that can serve as aquifers.

Outwash is a potential resource for construction sand and gravel (see Mineral Resources section below). Layers (or beds) of outwash may also occur within the fine grained gla­ cially deposited sediments that lie between the bedrock and today's land surface. Such sand and gravel deposits are generally porous and permeable; that is, fluids such as water can move easily among the grains. When thick enough, these deposits can be excellent aquifers (see Aquifer Delineation section below).

Organic-rich layers of sediment occur in some locations between layers of glacial sedi­ ment. These layers, which can serve as important marker beds, represent major intervals of warmer climate between glaciations during which soils developed and vegetation grew. Organic-rich deposits that separate major sequences of glacial sediments help geologists interpret the sequence of deposits and predict where outwash may occur below the surface. The low bearing capacity (weight the ground can safely support) of organic soils can affect construction.

Loess, a windblown silt, blankets much of the landscape in the Sugar-Pecatonica Assessment Area. It has important properties that make it an excellent parent material for the region's productive soils: it crumbles easily when lightly squeezed between the fingers, drains well yet has good moisture-holding capacity, and contains no pebbles or cobbles to interfere with plowing. Loess is derived from sediments that were deposited along the major melt­ water valleys, such as the valley, by sediment-laden meltwater flowing from the melting glaciers to the northeast. During winter, when there was little water to feed the rivers, the sediment in the river valleys dried out. Prevailing westerly winds picked up the finer sediments-silt, fine sand, and some clay-from the floodplain and blew them across the landscape. Loess is thickest immediately east of the valleys and thins rap­ idly with distance eastward.

Regional Glacial History

Hundreds of records (logs) and samples of sediments from borings drilled throughout the assessment area are stored and catalogued at the Illinois State Geological Survey. Many borings penetrated the entire sequence of glacial sediments overlying bedrock and provide the record from which the general glacial history of the region has been interpreted.

Several studies of the glacial geology of north-central and northwestern Illinois have been conducted over the past several decades, among them Shaffer (1956), Hackett (1960), Kempton (1962), Kempton and Hackett (l968a and 1968b), Frye and others (1969), and Berg and others (1985). Berg and others summarized regional interpretations of the gla­ cial geology and revised the" understanding of the region's glacial history on the basis of their field studies and additional data from samples available from drilling. However, their study covered only the eastern half of the Sugar-Pecatonica Assessment Area; the

14 glacial units in the rest of the area were described in Willman and Frye (1970) and mapped by Lineback (1979). From these sources, a brief glacial history and description of the glacial landscape can be summarized.

The glacial sediments in the Sugar-Pecatonica Assessment Area were deposited by glaciers of the llIinois Episode, the next to last major glacial advance into the state during the Great Ice Age (Willman and Frye 1970, Hansel and Johnson 1996). Meltwaters from these, and possibly earlier, glaciers may have deepened the bedrock valleys, such as the Pecatonica Bedrock Valley (see Bedrock Geology section). Some sand layers in the lowest parts of the valleys may also have been deposited by meltwaters of glaciers before and during the llIinois Episode.

At least three tills, representing three different pulses of the Illinois Episode glacier, under­ lie the loess cover of the Sugar-Pecatonica Assessment Area: from oldest to youngest they are the Ogle, the Winslow, and the Argyle (Willman and Frye 1970, Lineback 1979; Figure 5).

The Ogle, found over most of the central part of the assessment area, is generally a sandy, tan to gray-brown till that is thin and discontinuous and interbedded with sand and gravel. It has been intensely eroded but can be seen in many small outcrops that include the under­ lying bedrock. The Winslow, found only in the northwestern part of the assessment area, is a dark gray, clayey till. The Argyle, a sandy, gravelly pinkish tan till found in the east­ ern and southeastern part of the assessment area, was originally thought to be deposited by a glacier during the Wisconsin Episode (Willman and Frye 1970). However, an earlier soil (the Sangarnon Soil) that developed between the Illinois and Wisconsin Episodes of glaciation was found in the Argyle, so this till is now classified as an Illinois Episode deposit (Berg and others 1985).

The sequence of deposits, as well as their position on the landscape and their relationships to each other, has been difficult to unravel because of a combination of depositional and erosional circumstances (Berg and others 1985). The major factors contributing to the difficulty are (I) a highly irregular bedrock surface that has a great deal of local relief, (2) a thin cover of drift with few exposures of more than one till in anyone locality, (3) the similar appearance of the weathered tills in the field, and (4) the lack, due to ero­ sion, of preserved early soils developed in the tills. Nevertheless, the glacial history of the area can be summarized as the occurrence of several pulses of ice advance during the llIinois Episode, followed by an event of widespread high-velocity meltwater that flowed across the uplands and eroded and removed some of the early soils (Berg and others 1985). Later, deposition of windblown silt followed, which left a covering of loess across the entire area.

15 Thickness of Materials

Drift throughout most of the assessment area is thinner than 25 feet, and numerous outcrops of bedrock can be observed throughout the region. However, more than 200 feet of drift overlies the bedrock valleys near the east boundary of the assessment area (Figure 6; Piskin and Bergstrom 1975).

The three tills in the area are each generally thinner than 20 feet. The Ogle and Winslow, especially, are thin and discontinuous and appear in many small outcrops capping bedrock exposures. Sands and gravels in the bedrock valleys, where overlain by modern stream alluvium (Cahokia Alluvium, Figure 5), may be considerably thicker. Localized areas of lake silts (Equality Fonnation and Teneriffe Silt; Figure 5) that resulted when glacial meltwater temporarily backed up into small valleys tributary to the larger streams, such as the Pecatonica and Sugar Rivers, are usually several feet thick. The loess cover, as indicated by thickness contour lines in Figure 5, is as thick as 15 feet in the westernmost tip of the area, but thins to about 5 feet at the east boundary.

16 -J

o 5 10 15 20 I

-- river or stream II1II Cahokia Alluvium Fm. (ea) D. " .. Henry Fm. -outwash- m Tenneriffe Silt Its) open water (wI Mackinaw facies lhm) -- county boundary Q Peoria and Roxana Silts (prs) Wasco facies lhw) Peerl Fm. Ipe) 0 not mapped as - Quaternary (nq) assessment araa ~ Glasford Fm. , Equality Fm. (eq) Winnebago Fm. -- - boundary !< I 0 formation boundary -Jake sediments- Sterling Till (ga) - Argyle Till (wla' N Ogle Till (go) loess thickness Winslow Till (gw) I - contour Figure 5. Glacial Geology (modified after Lineback 1979, Hansel and Johnson 1996) \,

______L WINNEBAGO OGLE CO.­ ------­

o 5 10 15 20 -­ river or stream I! I 0 less than 25 feet 200-300 fe.t Miles -- county boundary 0 25-50 f••t 300-400 f••t ! - - assessment area N 50-100 f••t -0 no drift boundary I 100-200 f••t • Figure 6. Thickness of Glacial Drift (modified after Piskin and Bergstrom 1975) References

Berg, R.C., J.P. Kempton, L.R. Follmer, D.P. McKenna, R.J. Krumm, J.M. Masters, R.C. Anderson, R.L. Meyers, J.E. King, H.E. Canfield, and D.E. Mickelson, 1985, and Wisconsinan Stratigraphy and Environments in Northem Illinois-The Altonian Revised: Illinois State Geological Survey Guidebook 19 (32"" Field Confer­ ence of Midwest Friends of the Pleistocene), 177 p.

Frye, J.C., H.D. Glass, J.P. Kempton, and H.B. Willman, 1969, Glacial Tills of Northwest­ ern lllinois: Illinois State Geological Survey Circular 437,45 p.

Hackett, J.E., 1960, Groundwater Geology of Winnebago County, Illinois: Illinois State Geological Survey Report of Investigations 213, 63 p.

Hansel, A.K., and W.H. Johnson, 1996, Wedron and Mason Groups-Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lobe Area: Illinois State Geological Survey Bulletin 104, 116 p.; plate 1: Quaternary Deposits of Illinois (map).

Kempton, J.P., 1962, Stratigraphy of the Glacial Deposits in and adjacent to the Troy Bedrock Valley, : Ph.D. dissertation, University of lllinois at Urbana­ Champaign, 129 p.

Kempton, J.P., and J.E. Hackett, 1968a, The Late Altonian (Wisconsinan) Glacial Sequence in Northern Illinois, in Means of Correlation of Quaternary Successions: International Association of Quaternary Research Proceedings, 7~ Congress, Princeton University Press, Princeton, N.J., p. 535-546.

Kempton, J.P., and J.E. Hackett, 1968b, Stratigraphy of the Woodfordian and Altonian drifts of central northern Illinois, in The Quaternary of lllinois: University of Illinois College of Agriculture (Urbana) Special Publication 14, p. 27-34.

Lineback, lA., 1979, Quaternary Deposits oflllinois: Illinois State Geological Survey, 1:500,OOO-scale map.

Piskin, K., and R.E. Bergstrom, 1975, Glacial Drift in lllinois-Thickness and Character: Illinois State Geological Survey Circular 490, 35 p.

Shaffer, P.R., 1956, Farmdale Drift in Northwestern Illinois: Illinois State Geological Survey Report of Investigations 198, 25 p.

Willman, H.B., and J.C. Frye, 1970, Pleistocene Stratigraphy of Illinois: lllinois State Geological Survey Bulletin 94, 204 p.

19 Modern Soils and the Landscape-Influences on Habitat and Agriculture

The Sugar-Pecatonica Assessment Area contains some very productive soils, as indicated by the extensive distribution of agricultural land cover (Figures 11 and 12). Soil develop­ ment in the area is strongly influenced by geologic, topographic, and biologic factors. The influences of geology and topography on soil development are discussed here. Geology, topography, and soil types combine to produce numerous types of habitats that are condu­ cive to the development and survival of various natural plant and animal communities.

Geologic Factors

Loess, till, outwash, bedrock, and alluvium are the dominant parent materials of the soils in this assessment area. These materials differ significantly in their permeability, erodi­ bility, and physical and chemical characteristics. By affecting water table elevation, erosion, sedimentation, and water chemistry, these differences create localized habitats. Soil texture, acidity, and other physical and chemical characteristics are very important in determining land use and land cover (see Land Cover Inventory section below).

Loess is the initial parent material for about 80% of the soils in the Sugar-Pecatonica Assessment Area. The overall thickness of windblown silt (loess), in which modem soils have developed, varies considerably across the Sugar-Pecatonica Assessment Area, but its distribution across the landscape is rather continuous, as are its physical and chemical characteristics. Loess is generally thickest in the southern and western part of the assess­ ment area and thins toward the north and east, where it may be very thin or missing. Also affecting soil development are the materials underlying the loess. Sandy loam till is found throughout the area (about 35% of the soils have developed partially into the underlying lllinoian till); limestone and shale bedrock are important parent materials for soil devel­ opment in local areas where erosion has removed the overlying loess cover. Limestone and shale bedrock has directly influenced about 18% of the soils in the area.

Topographic Factors

Topographic influences (Figure 7) on drainage, erosion, and deposition are important in the long-term development of the landscape. Differences in the frequency, rate, and magni­ tude of surficial geologic processes have created many combinations of slope angle, slope length, and slope orientation that influence local drainage, erosion, and sedimentation.

20 - ".J

WISCONSIN

Topography of a land surface isths·physical configuration oftheland in terms of the difference in elevations. Topographic features are commonly illustrated by means of contour lines. Contour lines represent the same elevation along their entire length. The relative proximity of adjacent contours :t depicts the slope ofan area. For example, the closer together the contours. the steeper the land surface; the farther apart the contour lines, the flatter the land.

~

o 5 10 15 20 Here the interval between contour lines county boundary I represents about 33 feet (10 meters) of Miles elevation difference. Surface elevation assessment area ranges from about 1148 feet (350 meters) boundary above sea level down to 721 feet (220 I meters) above sea level. topographic contour (10 meter interval) I

Figure 7. Topography of the Land Surface 1

I ~

,I 01 ~l 1 81-I ~ 0 1 0 1 -'1 _ L WINNEBAGO CO. ______.-L --_ OGLE CO.------I

CARROLL CO. 1 I ! 1 L __ 1 o 5 10 15 20 I I I I I Miles

o lAMA-MUSCATINe-SABLE (lLOO2) Ei3a PAlSGROVE·DUBuaUE·FAYETTE (IL0591 HI ELUOTT-ASHKUM-VAANA IIL0161 _ WARSAW-LORENZO-DAKOTA (lL022) county boundary Q ASHDALE·DODGEVILlE·TAMA (IL025) 0 PECATONICA-WHALAN-FLAGG (llO75) 0Jl DERINDA-ELEROY-MASSBACH (llOe5) 0 PLANO-GRISINOLD·RINGWOOO (lL0151 assessment area boundary g SAWMILL-GENESEE-LAMON (IL02a) [S] TAMA·ASHOALE-MUSCATINE (l107e) ~ FOX-CASCo-RODMAN \IL053) 0 OGLE-DURAND-lAMA (lLOO7) soil association OJ] ROZETTA-FAYEITE·HICKORY {Il034j 0 DRUMMER·PLANO-ELBURN (llO121 EZa FAYETTE-ST. CHARLES·RADFORD UL043j unit boundary ISSJ FLAGG·PECATONlCA-KENDAlL jfL0391 o lAMA·MUSCATINE-SABLE (llOO2) _ JASPER-LA HOGUE·SELMA UL023J

Figure 8. Soil Associations of the Sugar-Pecatonica Assessment Area Modifications by human activities are also creating significant changes in surficial pro­ cesses (discussed in Soil Erosion and Sedimentation subsection below).

The upland areas between tributary drainages are commonly level and poorly to some­ what poorly drained. Prime farmland is located in these areas, as shown by Figure II. More than 60% of the land in the Yellow Creek, East Branch Richland Creek, North Branch Otter Creek, Sumner Creek, and Rhule Creek subbasins is in row-crop agriculture (see Figures II, 13, and Appendix B). Downstream portions of each subbasin, however, commonly have greater amounts of pasture and forest cover; this increase demonstrates the effect topography and soil erosion have on land use. This relationship is shown well in the figures in the Land Cover Inventory section of this report.

Soil Classification

The soils in the Sugar-Pecatonica Assessment Area are classified predominantly into two soil orders, Alfisols and Mollisols. Alfisols and Mollisols can be differentiated by the accu­ mulation of organic matter in the upper soil horizon: Mollisols are rich in organic matter and have a darker soil color (black to dark brown), whereas Alfisols are not as organic rich and have thinner upper soil horizons. In general, Mollisols have developed under natural or marsh vegetation, whereas Alfisols have developed under forest vegetation. Prairie grassland soils (Mollisols) tend to be more fertile. Poorly and very poorly drained Mollisols and Alfisols are common along drainages, floodplains, and flat upland areas and can play an important role in the development and maintenance of localized habitats.

There may also be scattered occurrences ofEntisols and Inceptisols on floodplains and sandy outwash areas, and along steeper, eroded uplands. Entisols and Inceptisols are soils with minimal soil horizon development. They occupy small acreages in the area, but are still significant because they help create niche communities (for example, where exceptionally sandy sediments exist).

Seventeen soil associations are found in the Sugar-Pecatonica Assessment Area (Figure 8). The thick to moderate loess cover has provided relatively uniform parent materials, and topography associated with stream incision has controlled the pattern of erosion. The most widespread associations are the Tama-Muscatine-Sable (15.4% of the assessment area), Ashdale-Dodgeville-Tama (13.1 %), and Pecatonica-Whalan-Flagg (9.7%). The more pro­ ductive soils have developed in thicker loess areas and tend to be Mollisols, which owe their fertility, in part, to their high organic-matter content. Many have more than 4.5% organic matter in the plow zone. The upland subbasins devoted to row-crop agricul­ ture are dominated by the Tama, Sable, Drummer, Muscatine, and other very productive Mollisols (see Figure 8).

23 In general, the soils classified within the same soil association will behave in a similar fashion and can be treated as a single unit for general planning purposes. Differences in drainage class are often the reason for differences in soil characteristics on a local scale.

Soil Erosion and Sedimentation

In areas where slopes of less than 5% (5 vertical feet in 100 horizontal feet) predominate, the potential for soil erosion is generally low. The general lack of drainage dissection in parts of the flat upland and floodplain areas, however, combined with the slow permeability of the relatively fine textured underlying sediments, makes high water tables, wet soils, severe stream and channel erosion, and sedimentation in streams and lakes a problem across the area. Flat upland and floodplain areas may be priIJ?e wildlife and wetland areas if they have not been cleared for cultivation.

Steeper slopes adjoining the floodplains of the streams are commonly susceptible to severe soil erosion through sheetwash and the development of extensive networks. This eroded sediment is often transported into small local channels and, ultimately, into the larger drainages. Uncontrolled erosion and sedimentation can seriously damage biologic communities that live in the channel or along streambanks by altering water tables, channel capacity, and channel geometry.

The extensive distribution and thickness of loess across the assessment area further contrib­ utes to the erosion hazard. Loess is easily entrained (picked up) and carried by moving water or wind. When dry, loess has the consistency of talcum powder and, if unprotected, is easily carried by wind. Loess is also particularly susceptible to erosion by running water because of its low shear resistance. It is rapidly incised and develops into a deeply dis­ sected landscape characterized by rills and that are difficult to control. On topo­ graphic maps, this characteristic drainage pattern is shown as highly crenulated (sinuous) topographic contour lines (see Figure 7). Where loess overlies less permeable geologic materials such as fine textured tills, the contrast in permeability and erodibility creates problems in land management, especially where the overlying loess unit is dissected or eroded and the less permeable underlying materials are exposed at or near the land surface.

Further increasing the erodibility of loess is the tendency for piping to develop within the soil. Piping is common when surface water penetrates to the subsurface and flows along macropores, such as open channels formerly occupied by roots, or along other natural frac­ tures in the ground. These linear "pipes" may enlarge and ultimately collapse, causing the ground surface to subside and form small surface drainage channels. These channels then begin to collect anq transport sediment and water as they are integrated into the local drain­ age system.

Areas with sloping, forested soils are especially susceptible to piping and are where hillside gullies often begin, even when the ground surface has not been disturbed by

24 deforestation or cultivation. Once begun, these small rills and gullies can quickly enlarge and erode upstream, extending the drainage network and directing increased water and sedi­ ment into the existing drainage system. The increased water and sediment discharge can initiate streambank erosion and streambed changes that are detrimental to the biologic com­ munities that inhabit the stream channels.

The extensive areas with grassland and forested land cover remaining in the Sugar-Pecatonica Assessment Area (Figures 15 and 16) indicate the difficulty of cultivating the steeper, more dissected and eroded landscape associated with major drainageways. These grass­ land and forested areas make up much of the existing prime wildlife habitat in the region. However, most of the eroded soils in the assessment area are located on slopes adjacent to stream channels, especially along the larger tributaries. The increase in slope angle and slope length in these areas creates a high potential for erosion.

Because of their topographic position, low wetland areas commonly receive accelerated deposition of sediment eroded from adjacent upland areas that have been in, or are currently in, cultivation or are in transition from undisturbed natural vegetation. This inundation of sediment can degrade wildlife food supplies and fill stream channels, decreasing their capacity to transport water and increasing the frequency of discharges of floodwater over the banks of streams. Pools along the streams are especially prone to damage from sedi­ mentation. Pesticides and other agricultural chemicals adsorbed to the sediment may also be deposited in channels and pools.

The physical load of sediment can accumulate quickly enough to bury part of the modem soil. Buried modem soils can be seen in some vertical soil profiles exposed along stream courses where a dark-colored former soil horizon lies beneath recently deposited, lighter­ colored sediments. Such buried modern soils are evidence of accelerated erosion resulting from human activity and are environmental indicators of current and potential problems in a drainage system.

Land Management Practices

Sound land use and management practices are especially important in controlling erosion on loessial soils. Damaged land should quickly be remediated and appropriate erosion control measures should be implemented to prevent additional damage to the landscape. It is unlikely that severe erosion caused by gullying on hillslopes will repair itself quickly enough to prevent extensive damage to adjacent land. Gullies that develop in loess can quickly become too deep for fann equipment to cross and eliminate through tillage. Fann­ ing along narrow ridgetops is generally not advisable because of the lack of transition zones along field edges to keep water from running off the field and entering hillside drainage channels.

The moderately slow permeability of many of the soils in the assessment area creates condi­ tions conducive to flooding and standing water during periods of high water table or heavy

25 precipitation. Some of the soils in the assessment area respond well to tiling, and field drainage has increased the volume and rate of runoff from cultivated fields. The increased stream discharge that results from tiling, however, is causing extensive erosion problems through channel widening and bank failure along many of the drainages.

In summary, the potential for water and wind erosion and the slow permeability of soil are the major management problems faced by land users in this area. The many potential problems created by the predominance of silty soil and variable topography can be allevi­ ated by appropriate conservation tillage practices and tiling.

County Soil Survey Reports

The Sugar-Pecatonica Assessment Area covers parts of five counties, with most of the area being in Stephenson and Winnebago Counties. The assessment area is covered by modem soil surveys, but only two (Winnebago and Jo Daviess) are digital. The informa­ tion from these reports, however, is available to interested individuals by contacting the Natural Resources Conservation Service (NRCS) office in that county. Using the appro­ priate software, these digital products can provide increased versatility in applying soil characteristics in environmental planning. As always, individuals or groups seeking to plan environmental restoration or conservation projects should contact local federal, state, and county offices to determine the nature of the soils and consult other appropriate environ­ mental databases.

The maps presented in this assessment report are too small in scale (not detailed enough) to provide for more than a cursory or reconnaissance level of interpretation. They are for general planning and information purposes only. Many county soil survey reports are being updated and converted to digital format. Although this process will take some years to complete, interested individuals and groups should check with their local NRCS agent to learn what materials and information are available for their specific location. The indi­ vidual soil maps presented in each county soil survey report are published at a scale of 1:15,840, or 1 inch equals 1,320 feet (0.25 miles). A smaller-scale soil association map is also included, usually at a scale of about I:250,000, or I inch equals about 4 miles. The scale of the soil association map is too small (contains too little detail) for site specific planning and analysis, but the individual soil sheets are ideal for this purpose. Even these maps, however, lack the detail necessary for specific site assessments for construction, but they are valuable for most environmental-scale planning.

The large-scale soil maps in county soil survey reports are valuable sources of informa­ tion regarding local conditions. Tabulated information within the report summarizes the capabilities and limitations of each soil series for various land uses, as well as its physical and chemical characteristics. There are also tables with information concerning the suit­ ability and capability of soils for supporting wildlife and woodland habitats.

26 References

Acker, L.L., G.T. Keller, and R Rehner, 1980, Soil Survey of Ogle County, lllinois: U.S. Department of Agriculture, Service and Illinois Agricultural Experi­ ment Station, University of Illinois at Urbana-Champaign, Soil Report 113, 242 p.

Alexander, J.D., and RG. Darrnody, 1991, Extent and Organic Matter Content of Soils in lllinois Soil Associations and Counties: Department ofAgronomy, College of Agriculture, University of Illinois at Urbana-Champaign, Agronomy Special Report 1991-03, 64 p.

Fehrenbacher, J.B., I.J. Jansen, and K.R Olson, 1986, Loess Thickness and Its Effect on Soils in Illinois: University of Illinois at Urbana-Champaign, Agricultural Experiment Station, Bulletin 782, 14 p.

Fehrenbacher, J.B., J.D. Alexander, I.J. Jansen, R.G. Darmody, RA. Pope, M.A. Flock, E.E. Voss, J.W. Scott, W.F. Andrews, and L.J. Bushue, 1984, Soils of Illinois: University of Illinois at Urbana-Champaign, Agricultural Experiment Station, Bulletin 778, 85 p.

Grantham, D.R., 1980, Soil Survey of Winnebago and Boone Counties, Illinois: U.S. Department of Agriculture, Soil Conservation Service and Illinois Agricultural Experi­ ment Station, University of lllinois at Urbana-Champaign, Soil Report 107, 279 p.

Hansel, A.K., and W.H. Johnson, 1996, Wedron and Mason Groups-Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area: Illinois State Geological Survey Bulletin 104, 116 p.; plate I: Quaternary Deposits of lllinois (map).

Ray, B.W., R. Rehner, and J.B. Fehrenbacher, 1975, Soil Survey of Carroll County, Illinois: U.S. Department of Agriculture, Soil Conservation Service and Illinois Agricultural Experiment Station, University of Illinois at Urbana-Champaign, Soil Report 98, 138 p.

Ray, B.W., J.B. Fehrenbacher, and R Rehner, 1976, Soil Survey of Stephenson County, Illinois: U.S. Department of Agriculture, Soil Conservation Service and Illinois Agricultural Experiment Station, University of Illinois at Urbana-Champaign, Soil Report 99, 133 p.

Tegeler, RA., 1996, Soil Survey of Jo Daviess County, Illinois: U.S. Department of Agriculture, Natural Resources Conservation Service and Illinois Agricultural Experi­ ment Station, University of lllinois at Urbana-Champaign, Soil Report 145, 224 p.

United States Department of Agriculture, 1994, State Soil Geographic (STATSGO) Data Base, Data Use Information: Natural Resources Conservation Service, National Soil Survey Center Misc. Publication no. 1492 [1994 revision], 35 p., plus appendices.

27 Wascher, H.L. J.D. Alexander, B.W. Ray, A.H. Beavers, and R.T. Odell, 1960, Charac­ teristics of Soils Associated with Glacial Tills in Northeastern Illinois: University of llIinois at Urbana-Champaign, Agricultural Experiment Station Bulletin 665, 155 p.

Wascher, H.L., B.W. Ray, J.D. Alexander, J.B. Fehrenbacher, A.H. Beavers, and R.L. Jones, 1971, Loess Soils of Northwest llIinois: University of Illinois at Urbana-Champaign, Agricultural Experiment Station Bulletin 739, 112 p.

28 Landscape Features and Natural Areas with Geologic Features of Interest

Landscape Features

The landscape features of the Sugar-Pecatonica Assessment Area were formed primarily by processes associated with glacial advances into and across a region of irregular bedrock topography. The assessment area falls almost entirely into the Rock River Country subdivision of the Till Plains Section of the Central Lowland Province (Leighton and others 1948; Figure 9). The Rock River Hill Country is typically a landscape of subdued rolling hills whose shape is controlled largely by the shape of the underlying bedrock surface. There is only a relatively thin cover of Illinois Episode glacial drift (see Glacial and Surficial Geology section).

The landscape can also be generally characterized as either upland and lowland. Much of the land in the Sugar-Pecatonica Assessment Area is in uplands-the extensive regions of higher ground that contrast with the lowland areas along the Pecatonica and Sugar Rivers. However, the term lowlands could also be applied to comparatively minor areas within the overall upland region.

Natural Areas with Geologic Features of Interest

According to records maintained by the lllinois Natural History Survey, four natural areas with geologic features of interest occur in the Sugar-Pecatonica Assessment Area (Illinois Natural Areas Inventory 1978). Two of these are in Stephenson County: (I) Dakota Prairie, which is under private ownership, features an excavation that exposes dolomite bedrock, and (2) Freeport Southeast Geological Area, also under private ownership, features an outstanding example of an ice-shoved hill. Ice-shoved hills were probably caused by the drag of a glacier as it advanced over the uneven bedrock surface, and gouged, shattered, thrusted, and folded the underlying bedrock. Such might especially have been the case if the preglacial drainage pattern presented a rough surface oriented at an angle to the advanc­ ing glacier (Cote and others 1970).

In Winnebago County, the Durand Southeast Geological Area (ownership type unlisted) features an outstanding exposure of fossils of sponge fauna (marine animals attached to the sea floor) that lived when the Ordovician-age Platteville dolomite was forming. Pecatonica Bottoms, also in Winnebago County and under public ownership, features a quarry in the Ordovician Galena dolomite.

29 --]C

[~:~] ~:=~elnwUlnd Ozark Plnteaus D ProtJint:e I· .. .1 ~::~~eLDwPlateaus

Coastal Plain Province

- province boundary physiographic ..... section boundary section subdivision boundary

county boundary

Sugar-Pecatonica • Ass8ssmentArea

Scale 1:3,000,000

o, ,

COASTAL PLAIN PROVINCE

Figure 9. Physiographic Divisions of Illinois (from Leighton, Ekblaw, and Horberg 1948) References

Cote, W.E., D.L. Reinertsen, and M.M. Killey, 1970, Guide Leaflet, Geological Science Field Trip, Freeport Area: Illinois State Geological Survey Guide Leaflet 1970C, 22 p.

Illinois Natural Areas Inventory, 1978: Department of Landscape Architecture, University of Illinois at Urbana-Champaign, and Natural Land Institute, Rockford, IL, 3 volumes.

Leighton, M.M., G.E. Ekblaw, and L. Horberg, 1948, Physiographic Divisions of Illinois: Illinois State Geological Survey Report of Investigations 129, 33 p.

31 Land Cover Inventory

Introduction

Land is the "raw material" of Illinois. Current and detailed information regarding this fundamental natural resource is essential for making wise decisions affecting the land and ensuring good stewardship. Land can be described in terms of a number of biological, geological, and hydrological characteristics. This section focuses on land cover, a princi­ pal factor of a region's land resource. The following paragraphs introduce and explain some basic concepts.

Land use refers to human activities on the land and emphasizes the principal role of land in describing a region's economic activities. Since the concept describes human activity, land use is not always directly observable; that is, we often cannot "see" the specific use of a parcel of land. For example, the presence of forested land in an aerial photograph or satellite image does not convey the possible multiple uses of that land, which may include recreation, wildlife refuge, timber production, or residential development.

Land cover refers to the vegetation and manmade features covering the land surface, all of which can be directly observed using remote sensing imagery. 1 Whereas land use is abstract, land cover is tangible and can be determined by direct inspection of the land surface; it is the visible evidence ofland use (Campbell 1987).

In association with other geologic data (such as aquifer location, distribution of water wells, and soil characteristics), geologists can use land cover and land use maps to infer geologic conditions in an area. For example, knowledge of land cover (such as location and extent of urban lands and cropland) is essential to accurately assess the potential for groundwater contamination. Land cover information is also important for resource con­ servation. In areas where natural vegetation predominates, land cover maps can be used as substitutes for ecosystems in conservation evaluation because vegetation effectively integrates many physical and biological factors in a geographic area (Scott 1993).

Remote Sensing Products

Land use and land cover maps are derived directly from remote sensing imagery. Geologists use a variety of data sources to derive information concerning surface and

1 Remote sensing is the science of deriving infonnation about an object or phenomenon at or near the sur­ face of the earth through the analysis of data acquired by a carnera or sensor system located in an aircraft or orbiting satellite.

32 near-surface conditions, and the usefulness of remote sensing imagery for mapping geologic features has been long recognized (USGS 1994).

For assessments at the site level (for example, sample sites or plots) or small regions (for example, at the county level), land cover information is typically derived from the inter­ pretation of aerial photography. At the statewide level, land cover information is usually derived from the analysis of satellite imagery, and the resulting inventory offers accurate, regional-level information regarding surface cover characteristics.

Although agricultural lands dominate three-fourths of the surface of Illinois and many landscape features have been obscured as a result of 175 years of European settlement, under optimum ground conditions, remote sensing imagery can show subtle changes in the uppermost few feet of materials that are similar in detail to soils maps. Factors of bio­ diversity associated with resource quality, richness, and quantity can be estimated with remotely-sensed data, principally because a remote sensing approach can compare changes in land use over time (Stoms and Estes 1993).

In 1996, the Illinois Department of Natural Resources published Illinois Land Cover: An Atlas (IDNR 1996) and Illinois Land Cover: An Atlas on Compact Disc (IDNR 1996), which present the most recent and comprehensive inventory of the state's surface cover. Multitemporal, Landsat Thematic Mapper satellite imagery acquired during 1991-1995 was the principal data source. All of the land cover information presented in this section is derived from Illinois Land Cover: An Atlas on Compact Disc.

Land Cover Statistical Summary

Landsat Thematic Mapper satellite imagery acquired on October 3, 1992, and May 15, 1993, was used as the primary data source for the interpretation of the land cover infor­ mation for the Sugar-Pecatonica Assessment Area (IDNR 1996). The type and extent of land cover within the assessment area are presented in Table 1; for purposes of compari­ son, a statewide summary of land cover is provided in Table 2. In addition, Appendix B provides an inventory of land cover categories for each subbasin; to facilitate subbasin comparisons, the original 18 categories used in Table I have been consolidated into the 9 principal land cover categories used in Table 3.

Location and Area

These are the principal statistics about the Sugar-Pecatonica Assessment Area:

• The Sugar-Pecatonica Assessment Area incorporates portions of five northwestern Illinois counties: Carroll, 10 Daviess, Ogle, Stephenson, and Winnebago Counties (Figure I). • The assessment area has a surface area of 796.4 square miles (509,680 acres), which represents approximately 1.4% of the total surface area of Illinois.

33 Table 1. Principal Land Cover of the Sugar-Pecatonica River Assessment Area (IDNR 1996)*

Category Sq. Mi. Acres % Area Agricultural Land 704.2 450,686 88.4 Row Crops 361.7 231,476 45.4 Small Grains 62.8 40,214 7.9 Rural Grassland 279.7 178,982 35.1 Orchards and Nurseries 0.0 14 0.0 Forest and Woodland 35.9 22,989 4.5 Deciduous, closed canopy 33.7 21,534 4.2 Deciduous, open canopy 1.8 1,126 0.2 Coniferous 0.5 330 0.1 Urban and Built-Up Land 22.4 14,294 2.8 High Density 1.5 975 0.2 . Medium Density 2.5 1,580 0.3 Low Density 4.3 2,732 0.5 Transportation 4.5 2,847 0.6 Urban Grassland 9.6 6,160 1.2 Wetland 22.4 14,306 2.8 Shallow MarshlWet Meadow 7.1 4,548 0.9 Deep Marsh 0.6 366 0.1 Forested 13.4 8,549 1.7 Shallow Water 1.3 843 0.2 Other Land 11.6 7,405 1.5 Lakes and Streams 11.4 7,276 1.4 Barren and Exposed 0.2 128 0.0 Totals 796.4 509,680 100.0

* Small errors in totals are due to rounding.

• Twenty-one subbasins compose the assessment area, ranging in size from 3.9 square miles (2,542 acres) (Rhule Creek Subbasin) to194.4 square miles (124,427 acres) (Yellow Creek Subbasin) (Figure 10).

Agricultural Land

Agricultural Land comprises two principal categories, Cropland and Rural Grassland (Table 3). As a principal land cover category, Cropland is an aggregate of three classes (Table 1), Row Crops (com, beans, and other row-tilled crops), Small Grains (oats, wheat, barley, etc.), and OrchardsINurseries (Table 1). Rural Grassland includes pastures, alfalfa, hay, roadsides, fence lines, waterways, and other grassland cover located in rural areas.

34 Table 2. Land Cover of llIinois (IDNR 1996)*

Category Sq. Mi. Acres % Area Agricultural Land 43,638.8 27,928,797.0 77.4 Row Crops 30,600.4 19,584,247 54.3 Small Grains 3,166.0 2,026,268 5.6 Rural Grassland 9,847.5 6,302,371 17.5 Orchards and Nurseries 24.9 15,911 0.0 Forest and Woodland 6,388.4 4,088,623 11.4 Deciduous, closed canopy 5,618.0 3,595,538 10.0 Deciduous, open canopy 657.8 421,013 1.2 Coniferous 112.6 72,072 0.2 Urban & Built.Up Land 2,361.6 2,087,395 5.8 High Density 476.7 305,065 0.8 MediumlHigh Density 186.5 119,352 0.3 Medium Density 729.5 466,894 1.3 Low Density 392.5 251,180 0.7 Transportation 492.0 314,866 0.9 Urban Grassland 84.4 630,038 1.8 Wetland 1,828.6 1,170,550 3.2 Shallow MarshlWet Meadow 219.8 140,664 0.4 Deep Marsh 54.5 34,855 0.1 Swamp 18.3 11,726 0.0 Forested 1,264.0 808,987 2.2 Shallow Water 272.4 174,318 0.5 Other Land 1,228.7 786,361 2.2 Lakes and Streams 1,203.4 770,183 2.1 Barren and Exposed 25.3 16,178 0.1 Totals 56,346.5 36,061,727 100.0

• Small errors in totals are due to rounding.

• 88.4% of the assessment area is devoted to agricultural land cover, amounting to 704.2 square miles (450,686 acres) (Figure II). Statewide, land devoted to agricul­ ture amounts to 77.5% of the surface area of Illinois (Figure 12, Tables I and 2). • Agricultural land cover comprises at least 90% of the surface area in II of the 21 sub­ basins and at least 75% of the surface area in 20 subbasins in the assessment area (Figure 13). Just two of these subbasins, Yellow Creek and Pecatonica River (upper), account for one-third of all of the agricultural land acreage in the assessment area. • Cropland is the dominant principal land cover across the assessment area and rep­ resents over one-half (53.3%, or 271,704 acres) of the total surface area (Figure 14). At the subbasin level, 15 of 21 subbasins have 50% or more Cropland land cover.

35 Table 3. Principal Land Cover ofthe Sugar-Pecatonica River Assessment Area (IDNR 1996)*

Category Sq. Mi. Acres %Area Agricultural Land 704.2 450,686 88.4 Cropland 424.5 271,704 53.3 Rural Grassland 279.7 178,982 35.1 Forest and Woodland 35.9 22,989 4.5 Urban and Bnilt-Up Land 22.3 14,294 2.8 UrbanlBuilt-Up 12.7 8,134 1.6 Urban Grassland 9.6 6,160 1.2 Wetland 22.4 14,306 2.8 Forested 13.4 8,549 1.7 Nonforested 9.0 5,757 1.1 Other Land 11.6 7,405 1.5 Lakes and Streams 11.4 7,276 1.4 Barren and Exposed 0.2 128 0.0 Totals 796.4 509,680 100.0

• Small errors in totals are due to rounding.

• Exceeded in acreage only by Cropland, Rural Grassland is the second-highest occur­ ring land cover in the assessment area and represents 35.I % (178,982 acres) of the total surface area (Figure 15). At the subbasin level, Rural Grassland accounts for over 30% of the surface area in 20 of 21 subbasins (Figure 13), which indicates the amount of moderately sloping land within the assessment area.

Forest and Woodland

The Forest and Woodland land cover category is defined as land areas that are covered predominantly with trees and woody vegetation. This principal land cover category is an aggregate of three classes (Table 1): Deciduous Woods (closed-canopy wooded areas char­ acterized by tree species that undergo seasonal change), Open Woods (open-canopy wooded areas), and Coniferous Woods (wooded areas dominated by pines and other coniferous trees).

• Forest and Woodland land cover comprises 4.5% of the assessment area, which amounts to 35.9 square miles (22,989 acres) (Figure 16, Table 3) and is the third most prevalent land cover in the assessment area. Statewide, Forest and Woodland cover accounts for I 1.3% of the surface area of Illinois (Figure 12, Tables I and 2). • At the subbasin level, Forest and Woodland accounts for less than 10% of the surface area of 19 of the 2 I subbasins (Figure 17). This small percentage is consistent with the lack of highly dissected topography associated with steep valley side slopes in the Sugar-Pecatonica Assessment Area.

36 Wetland

The Wetland principal land cover category is divided into two broad types, Forested Wet­ land and Nonforested Wetland. Forested Wetland includes swamps (forested wetlands with standing water during all or most of the year) and bottomland forests (forested wetlands that are temporarily or seasonally flooded). Nonforested Wetland includes shallow marsh/wet meadow (areas characterized by standing water or saturated soils for brief to moderate periods during the growing season), deep marsh (areas characterized by standing water or saturated soils on a semipermanent or permanent basis during the growing season), and shallow water wetland (permanently flooded areas less than 20 acres in extent and less than about 6.5 feet deep).

• Wetland land cover comprises only 2.8% of the total area of the Sugar-Pecatonica Assessment Area, which amounts to 22.4 square miles (14,306 acres) (Figure 18). Statewide, Wetland accounts for 3.2% of the total surface area ofllJinois (Figure 12, Tables I and 2). • Approximately 60% (59.8%) of the Wetland land cover in the assessment area is Forested Wetland, and nearly 32% (31.8%) of the Wetland cover comprises shal­ low marsh/wet meadow (Nonforested Wetland) habitat (Table 3). Figure 18 indi­ cates that most of the Wetland land cover is concentrated in the immediate flood plains of the Pecatonica and Sugar Rivers. • At the subbasin level, five subbasins account for slightly over two-thirds (67.7%) of all of the Wetland cover within the assessment area. These include the , Raccoon Creek, and the Pecatonica River (middle, lower middle, and lower) Subbasins (Figure 19).

Urban and Built-Up Land

Urban and Built-Up Land comprises land areas covered with manmade structures, as well as open space that is incorporated within urban areas. This principal land cover category is composed of two broad categories, UrbanlBuilt-Up Land and Urban Grassland. Urbani Built-Up Land includes land surfaces that have been developed, or "built-up" with struc­ tures such as buildings, roadways, parking lots, driveways, and other such structures that form impervious surfaces. On the basis of the relative amount of impervious surface area, Urbani Built-Up Land is divided into subclasses ranging from High Density (all or nearly all ofthe land surface is covered with manmade structures) to Low Density (only a portion of the land is covered with manmade structures, intermixed with other cover such as grassland, wooded lands, etc.) (Table 1). Urban Grassland includes open space such as residential lawns, parks, golf courses, and other managed grassland in urban and built-up areas.

• Urban and Built-Up Land comprises 2.8% of the assessment area, which amounts to 22.4 square miles (14,294 acres) (Figure 20). By comparison, 5.8% of the Illinois surface area is composed of Urban and Built-Up Land (Figure 12, Tables 1 and 2).

37 • Of the total amount of Urban and Built-Up Land present in the assessment area, Built-Up Land accounts for 56.9% (8,134 acres) and Urban Grassland accounts for the remaining 41.9% (6,160 acres). These amounts indicate the large amount of open space still existing within built-up areas or areas undergoing development. • Whereas a number of small urban centers are distributed across the assessment area, at the subbasin level almost one-third (31.4%, or 4,482 acres) of all the Urban and Built-Up Land is concentrated in the Pecatonica River (upper middle) Subbasin, where the city of Freeport is located (Figures 20 and 21). An additional 10% (1,264 acres) of the remaining Urban and Built-Up Land is concentrated in the Lake Summerset development situated in the South Branch Otter Creek Subbasin (Figures 20 and 22). • Because the urbanized area of Freeport is situated within the flood plain of the Pecatonica River and the Lake Summerset development is located within a water­ shed tributary to the Sugar River, the potential for adverse impacts to the natural cover, drainage, and groundwater from urban land use is a concern.

Notes on Land Cover Maps

In addition to Illinois Land Cover: An Atlas (IDNR 1996), two other publications relating to the statewide land cover inventory are available from the lllinois Department of Natural Resources: (1) Illinois Land Cover: An Atlas on Compact Disc (IDNR 1996), which con­ tains the statewide land cover digital database; and (2) Land Cover ofIllinois (IDNR 1996), a printed I:500,000-scale map. All are available through DNR Conservation 2000 Publi­ cations (524 South Second Street, Springfield, II.. 62701-1787; telephone: 217-782-7940). Land cover information and data are also available through the DNR website at

http://dnr.state.il.us/ctapllandmap.htrn

The maps reproduced in this volume are small-scale versions of preliminary work maps used by the authors in preparation of their sections. The level of detail in these maps is limited by the page size and type and quality of printing available for the reproduction of this report. In general, these maps are suitable for general planning and information purposes. Higher-detail and higher-resolution maps suitable for more specific applications and assessments can be consulted or obtained by contacting the authors at the Illinois State Geological Survey.

It is useful to discuss appropriate mapping scales that should be used as guidelines with applications involving the statewide land cover database. Using standardized map scales and associated National Map Accuracy Standards (NMAS) established by the U.S. Geo­ logical Survey, maps developed from the land cover database can range from 1:62,000 (I inch =1 mile) to 1: 100,000 (I inch =1.6 miles) and still maintain NMAS standards for raster data possessing a ground spatial resolution of 28.5 meters (93.5 feet). Of course, any smaller-scale maps (for example, 1:250,000) will also maintain NMAS accuracy standards.

38 Given these guidelines, the lllinois land cover database can support regional applications but should not be expected to fulfill the needs of site-specific projects.

References

Campbell, J.B., 1987, Introduction to Remote Sensing: The Guilford Press, New York, 551 p.

lllinois Environmental Protection Agency, 1994, lllinois Water Quality Report, 1992-1993, Volume IT, IEPA Bureau of Water, Springfield, IL, 181 p.

lllinois Land Cover-An Atlas, 1996: lliinois Department of Natural Resources, Springfield, Illinois, IDNRlEEA-96/05, 157 p.

Illinois Land Cover-An Atlas on Compact Disc, 1996: Illinois Department of Natural Resources, Springfield, Illinois.

Landcover of lllinois, 1996: Illinois Department of Natural Resources, Springfield, lllinois, Illinois Scientific Surveys Joint Report 3; 1:500,OOO-scale map.

Scott, J.M., F. Davis, B. Csuti, R. Noss, B. Butterfield, C. Groves, H. Anderson, S. Caicco, F. D'Erchia, T.e. Edwards, Jr., J. Ulliman, and R.G. Wright, 1993, Gap Analysis-A Geographic Approach to Protection of Biological Diversity, Wildlife Monograph, No. 123,41 p.

Stoms, D.M., and J.E. Estes, 1993, A Remote Sensing Research Agenda for Mapping and Monitoring Biodiversity: International Journal of Remote Sensing, v. 14, p. 1839-1860.

United States Geological Survey, 1994, Airborne Remote Sensing for Geology and the Environment-Present and Future, K. Watson and D.H. Knepper (eds.): USGS Bulletin 1926, 43 p.

39 Sugar Pecatonica Rivet River (upper) Riohland Creek

.\ 01 ~I fill -I ~ 0 1 0 1 ,I ------~ CARROLL CO. -- -­--

L _

o 5 10 15 20 Miles assessment area assessment BreB o boundary ! subbasin county boundary N boundary I

Figure 10. Subbasins of the Sugar-Pecatonica Assessment Area L

Apple River

.1 °1 ~I ~I ~I~ 0: -! !o. g I q,; L WINNEBAGO CO. ___ ~ _.L OGLE CO:------I CARROLL CO. ) .E' Lake Ilwer ; "\ Carroll ~

V~ IL _

o 5 10 15 20 assessment area I agriculture ­ Miles boundary D other -- river or stream I - N open waterl -- cOlJnty boundary ~ - wide river i Figure 11. Agricultural Land Cover in the Sugar-Pecatonica Assessment Area 100

80

Q) 60 Cl ~ ~ Q) a.. 40

20

Agricultural Land Woodland Urban Land Wetland Other Land

[ill Illinois III Sugar-PecatonicaIAssessment Area

Figure 12. Comparison of Principal Land Cover for the State of Illinois and the Sugar-Pecatonica Assessment Area 1 • 4<

100 --r------~

90

80

70

Q) 60 N c: 50 ~ Q) a. 40

30

20

10

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Subbasin

__ Agricultural Land -e- Cropland -e-- Rural Grassland

1 Yellow Creek 11 Pink Creek 2 Waddams Creek 12 Sumner Creek 3 East Branch Richland Creek 13 Coolidge Creek 4 Richland Creek 14 Rhule Creek 5 Cedar Creek 15 Sugar River 6 Rock Run 16 Raccoon Creek 7 Lost Creek 17 Pecatonica River (upper) 8 North Branch Otter Creek 18 Pecatonica River (upper middle) 9 South Branch Otter Creek 19 Pecatonica River (middle) 10 Otter Creek 20 Pecatonica River (lower middle) 21 Pecatonica River (lower)

Figure 13. Agricultural Land Cover by Subbasin from West (Left) to East (Right) across the Sugar-Pecatonica Assessment Area. -~ --C'~

1...J1I1I ... .?,.iiI' ---­

.1 °1 U I/) 1 1/)1 !!!I ~10 ~ °1 ·f ~I ~ L WINNEBAGO CO. ______---l.: OGLE CO.------I CARROLL CO. )-( Itjver ~ fl\#' 1L _

5 10 15 20 o assessment area I cropland ­ Miles boundary 0 other -- river or stream I - N open water! -- county boundary ~ - wide river I Figure 14. Cropland Land Cover in the Sugar-Pecatonica Assessment Area (IDNR 1996) · ~. , /.

---- *\'1£lYS

.1 01 ~I 001 ~I ~I~J 0 1 ~ -'1 L WINNEBAGO CO. ______-.L: OGLE CO.- -- --­------1 CARROLL CO. )-( Itiver ~ fl\#' IL _

o 5 10 15 20 rural grassland ­ assessment area Miles boundary 0 other -- river or stream ! - N open water! -- county boundary ~ - wide river I Figure 15. Rural Grassland Land Cover in the Sugar-Pecatonica Assessment Area (IDNR 1996) .. ~.

1 _

*\ij"'~;' ~~' , '~I'i":t,~ "~:,'t,'~..,·... . - i., '" ~ ,<,' .... ," --;"P';.l •• 1"'- ;'" ~,;. ' .. ~.~,. ~ 40:.'.~!' .,-~ "•.~.1'.' .'• ~ ...... ;< ., ...- ' ~'j.,.,... '. I ",",,,.J,eo","W Apple ., ~')'l'\~'''' River ..,.:. ... ,,/:'. ;"".,,' ",'i:'.; , -- . } ,~ ',,, .:P:.... -,'" ... ','., .~~ ,~, . ., J • "'J .,' ".,.. ' .... . 1 ~, ... ';0"" ", ,."' ... .' .. • 1..' ." ." .. I . .:",:/;,"'; . • "",,:' • •..."~ '" .. ..'' 4.··',' ..' ;-.." ' . ... A '0. _,."":~..: ~ '., ,.."'"~'" ..~. 1 ' .... • ' j,"... ,, • . ~.. C",:"...... J .... .".'"'" "1.&' ,.. ' .... '. .':'"''"" ...•....,.... ,... l .. ' 1 •. .'j,J..•..'<';.- .~ •., • I • " ." • V" • • ~ , • ., .. ~'7' '.I'''~'' ,_ .:.~,o,:,. ''''0':'''';''''' . ,....~.,•.- :c. ; I. : ~i.\.,. '.. , ,~ .' ..,~. fl . ' .• ..., I' -""C" .... ".'.;'." .. '11[:' J ., .' .", " .;f· '. !i'. \ .' (\,.:.' e· . " ~ ,',': ..0' ...... :.~ ,:.- .•",~- . ... •."', :.:"..,.s* ': ~,,'"""'J:":!"..... ' ""'.,..... '",..7"'., .... ," ,f•. ,-:-:"{,, 'f: '~'.,.!:t'., j,'.. , .... "'....,: •••• --'J':

o 5 10 15 20 assessment area forest or woodland ­ Miles boundary 0 other -- river or stream ! - N open water! -- county boundary ~ - wide river I Figure 16. Forest and Woodland Land Cover in the Sugar-Pecatonica Assessment Area (IDNR 1996) 100 -,------,

90

60

70

Q) 60 OJ .l'J c: 50 ~ Q) a. 40

30

20

10 o~~~~~~~~~~ 2 3 4 5 6 7 6 9 10 11 12 13 14 15 16 17 16 19 20 21 Subbasin

__ Forest & Woodland

1 Yellow Creek 11 Pink Creek 2 Waddams Creek 12 Sumner Creek 3 East Branch Richland Creek 13 Coolidge Creek 4 Richland Creek 14 Rhule Creek 5 Cedar Creek 15 Sugar River 6 Rock Run 16 Raccoon Creek 7 Lost Creek 17 Pecatonica River (upper) 8 North Branch Otter Creek 18 Pecatonica River (upper middle) 9 South Branch Otter Creek 19 Pecatonica River (middle) 10 Otter Creek 20 Pecatonica River (lower middle) 21 Pecatonica River (lower)

Figure 17. Forest and Woodland Land Cover by Subbasin from West (Left) to East (Right) across the Sugar-Pecatonica Assessment Area. --1:>, ",-,.',

WISCONSIN ----:,~~l~~,~--~v,.,.~ ~ j .. I lLI;: : II '. " ). .l,., • '.-l,. .. .; r: •.-A ' 1 , y r,r I l ,~ - I ,~. it" .' ~ I I , -

.\ 01 " ~I , I' fiji ,} >.1 ' .. 1 0~'f:i ~ L WINNEBAGO CO. ....,1 STEPHENSON CO. ------______...L ----,-T-----­ OGLE CO. I ttiver CARROLL CO. ) J 1 ~ 1 I fl\~~ " L _

o 5 10 15 20 open water! I forested and Miles nonforested wetland wide river assessment area I other - N -0 - boundary ~ river or stream I

Figure 18. Wetland Land Cover in the Sugar-Pecatonica Assessment Area (IDNR 1996) -Vi I

100 -,-----­ ~

90

80

70

Q) 60 F c: 50 ~ ~ 40

30

20

10

0~_...... ~~_ _..__~~!!!!!!l!!!!g;;~~_'i":~~~::::::j':::::YJ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Subbasin

__ Wetland -e- Forested -e--- Nonforested

1 Yellow Creek 11 Pink Creek 2 Waddams Creek 12 Sumner Creek 3 East Branch Richland Creek 13 Coolidge Creek 4 Richland Creek 14 Rhule Creek 5 Cedar Creek 15 Sugar River 6 Rock Run 16 Raccoon Creek 7 Lost Creek 17 Pecatonica River (upper) 8 North Branch Otter Creek 18 Pecatonica River (upper middle) 9 South Branch Otter Creek 19 Pecatonica River (middle) 10 Otter Creek 20 Pecatonica River (lower middle) 21 Pecatonica River (lower)

Figure 19. Forested, Nonforested, and Wetland Land Cover by Subbasin from West (Left) to East (Right) across the Sugar-Pecatonica Assessment Area '. 1\

WISCONSIN ----iI\ i .. ~; : c::~ ILLINOIS. ,­ 1

III1._------:-\b­1· ~ ~-l-~------\ ~ \ L__ ~~ 1 1 1 1 I I I .1 ~ 01 - _~ J.---.-I ­ ~I 1 1 ___ 1 13-I ~ -----+­ 1 0 / 1 0 1 -'1 ______L ~~~~~~~~_ ------~ -_?~t:~ OGLE CO. I CARROLL CO. )-( iVer lt ~ I V\~ 1L _

o 5 10 15 20 assessment area ! I I urban/built-up ­ Miles boundary 0 other -- river or stream I - N open waterl -- county boundary ~ - wide river I Figure 20. Urban and Built-Up Land Cover in the Sugar-Pecatonica Assessment Area (IDNR 1996) U\

•

IL Ridott ~ W-­

, • u.s. 20 • .... \

f>f> ~.o ,io U ~~'"'-'"'flo:' "'~f1{;'J' I '1....",,- ..fI "oS (J''l. eo" "' ~'" J

o 1 2 3 4 5 _ urban and built-up land ! I o other land cover Miles _ forested wetland o outside assessment area N! nonforested wetland assessment area boundary _ lake or stream I

Figure 21. Land Cover Detail Around Freeport, Illinois (IONR 1996) .. ~ .-.­ 100 -,-- ---,

90

80

70

Q) 60 OJ .l!! ~ 50 ~ Q) Cl. 40

30

20

10

O-.U:~~~~~:::::::!~--L~----l...-::::::i:::::::r::~~d-----'---~~=1J 2 3 4 5 6 7 8 9 10 11 12 13 14 15 18 17 18 19 20 21 Subbasin

__ Urban & Built-Up land

1 Yellow Creek 11 Pink Creek 2 Waddams Creek 12 Sumner Creek 3 East Branch Richland Creek 13 Coolidge Creek 4 Richland Creek 14 Rhule Creek 5 Cedar Creek 15 Sugar River 6 Rock Run 16 Raccoon Creek 7 Lost Creek 17 Pecatonica River (upper) 8 North Branch Otter Creek 18 Pecatonica River (upper middle) 9 South Branch Otter Creek 19 Pecatonica River (middle) 10 Otter Creek 20 Pecatonica River (lower middle) 21 Pecatonica River (lower)

Figure 22. Urban and Built-Up Land Cover by Subbasin from West (Left) to East (Right) across the Sugar-Pecatonica Assessment Area Part 2: Geology and Society

Most of us live, work, and play on the surface of the earth. But what we often fail to recog­ nize is that beneath the office building or factory where we work, beneath the home where we live, or beneath the park where we play, is a framework of geology that supports our lives on the surface. The geologic framework contains the mineral resources that are the raw ingredients of most of the manufactured materials that furnish our homes, offices, and playgrounds; and it provides the water that flows freely from the faucets we turn on and off daily. At the same time, the contamination of water resources, the slumping of banks along our roads, or damage from earthquakes are hazards that we don't think about until they happen-let alone realize that a supporting framework of geology affects why they occur.

The interrelatedness between geology and human society is so intimate and intricate that it is easier ignored than understood. Nevertheless, to understand and wisely use the natural heritage we value, we must consider the geological factors that are part of our daily lives. Some of the major ways geologic materials, geologic resources, and geologic processes affect modern society are discussed in the following sections.

53 Mineral Resources

Dolomite and limestone are the most important economic mineral resources produced in the assessment area. In 1997, 23 quarries produced crushed stone in the assessment area. Currently, no pits produce sand and gravel in the assessment area (Figure 23).

Data on production and employment are not available for the individual quarries or for the assessment area as a whole. The stone quarrying operations cater to the construction demands in this area. In addition to construction aggregates, some agricultural lime is also produced. The average unit value of this resource is relatively low. In 1996, the average unit value of crushed stone was about $5.47 per ton. Since the unit value is low, efficiency in production and transportation is important. Table 4 lists the quarrying operations in the assessment area.

Known or expected deposits of useful mineral commodities are sources for possible future exploitation (Figure 24). This assessment area is rich in dolomite and limestone resources, especially along the Pecatonica River bluffs in Stephenson and Winnebago Counties, which have good potential for future exploitation. The bedrock of Stephenson County consists primarily of the Ordovician Maquoketa, Galena, and Platteville groups. The Maquoketa, which is primarily shale, is rather soft and is of doubtful value as road material. Most of the quarriable stone is found in carbonate rocks of the Galena and Platteville groups. Urban and suburban residential and commercial zoning are making it very difficult for some quarries to expand into areas with known resources of high­ quality stone.

In addition to the abundant dolomite and limestone resources, there are some potentially valuable deposits of sand and gravel along the floodplains and channels of the Pecatonica and Sugar Rivers (Lineback 1979, Masters 1983). The primary source of sand and gravel in this area is the Cahokia Alluvium, which consists of poorly sorted sand, silt, or clay that contains local deposits of sandy gravel. In addition to the Cahokia Alluvium there are some relatively small deposits of sand and gravel that belong to the Pearl Formation and to the Wasco Member of the Henry Formation. In the Sugar River valley, sand and gravel of the Mackinaw Member of the Henry Formation may be present below the Cahokia, and it may be present at the surface near the juncture of the Sugar and Rock Rivers (Figure 5). Just south of the Wisconsin state line and west of the Sugar Creek valley, the Ordovician St. Peter Sandstone is at or near the surface. A silica sand resource, this formation is extensively used in llIinois in the making of glass and other industrial products (Berg and others 1984).

There are no minable deposits of coal or oil and gas in this assessment area.

54 I\.-

w;r;;nr~ ~ - I n WISCONSIN L, "I • ,,' i C('\ ILUNOIS (( Apple " ,::.:L '['ak, • 't~~'summerset River • Durand ~ • Davis,~·_I'-1

"". I\ C.' Dakota • ..0 \ . I • ,~ " Cedarville I Stockt0l) '0 ~. 1 • " ('OJ> • I ,', ~b.• I, • ',S', /!>~ ,,~,,"t;/-' • • .\ Pecatonica 01 ~I , L ':;0 '; ~ • fBI i -I ~I~J 0 1 ~ ""1 • ______L-- WINNEBAGO CO. ______--.L ------T------STEPHENSON CO. OGLE CO. ------I \liver CARROLL CO. ) J Lak, I ~ #' "'\ Carroll I 1L _ t~ FOrreston ", L-C .. 'Lanark

o 5 10 15 20 -- assessment area ! I limestone quarry boundary Mites • municipal area -- county boundary ! 0 N open water! -- river or stream ~ I - wide river Figure 23. Active Limestone Quarries ',_:-,

---- 48808&IJ

River J

.1 °1U Ul 1 Ull ~I ~I °1 gl ~ L _ WINNEBAGO CO. ______..-L' OGLE CO.- ­------I CARROLL CO. ) ~ Itivef ~ 'l\~ 1L _

o 5 10 15 20 potential source of sand open water/ I and gravel wide river Miles assessment area ~ potential source of stone -- - - boundery I 0 not mapped as mineral -- county boundary N source ~ river or stream I Figure 24. Potential Mineral Resources in the Sugar-Pecatonica Assessment Area Table 4. Mineral Producers in the Sugar-Pecatonica Assessment Area Limestone Bolen Quarry Farm Quarry #110 Sheely Aggregates Rockford Blacktop Construction 8200 W. White Eagle, Forreston, n.. 61030 P.O. Box 2071, Loves Park, n.. 61130 Phone: (815) 938-3311 Phone: (815) 654-4700 County: Stephenson County: Winnebago Mineral: Limestone Mineral: Limestone Brownsrnill Quarry Fish Hatchery Road Pit Sheely Aggregates Winnebago County Highway Department 8200 W. White Eagle, Forreston, n.. 61030 424 N Springfield Phone: (815) 938-3311 Rockford, n.. 61101-5097 County: Stephenson Phone: (815) 965-9431 Mineral: Limestone County: Winnebago Mineral: Limestone Brush Creek Quarry Sheely Aggregates Fritsch Quarry 8200 W. White Eagle, Forreston, n.. 61030 P.L. Dillon Limestone, Inc. Phone: (815) 938-3311 10216 E. Chelsea Road County: Stephenson Stockton, n.. 61085 Mineral: Limestone Phone: (815) 947-2857 County: Stephenson Buss Quarry Mineral: Limestone Rees Construction Co., Inc. 2918 Eleventh Avenue, Monroe, WI 53566 John Eaton Mine Phone: (608) 325-6819 Bauch Quarry Products County: Stephenson E. First Street, P.O. Box 28 Mineral: Limestone Pecatonica, n.. 610630 County: Winnebago Durand Quarry Mineral: Limestone Rogers Ready-Mix & Materials, Inc. P.O. Box 250, Byron, n.. 61010 Lobdell Quarry Phone: (815) 234-5363 Lobdell Sand & Gravel County: Winnebago 5777 Flansburg Road, Lena, n.. 61048 Mineral: Limestone Phone: (815) 563-4624 County: Stephenson Dwyer Quarry Mineral: Limestone Civil Constructors, Inc. P.O. Box 750, Freeport, n.. 610320 Monte Quarry Phone: (815) 235-2200 Civil Constructors, Inc. County: Stephenson P.O. Box 750, Freeport, n.. 61032 Mineral: Limestone Phone: (815) 235-2200 County: Stephenson Fairview Quarry Mineral: Limestone Sheely Aggregates 8200 W. White Eagle, Forreston, n.. 61030 Nieman Qnarry Phone: (815) 938-3311 Economy Excavating Co. County: Stephenson 1567 Heine Road, Freeport, n.. 61032 Mineral: Limestone Phone: (815) 235-4290 County: Stephenson Mineral: Limestone

57 Oppold Quarry Tessendorf Quarry Economy Excavating Co. Cox R.E. Construction, Inc. 1567 Heine Rd., Freeport, IL 61032 P.O. Box 277, Lena, IL 61048 Phone: (815) 235-4290 Phone: (815) 369-4115 County: Stephenson County: Stephenson Mineral: Limestone Mineral: Limestone Rock City Quarry Truman, Ed Quarry Civil Constructors, Inc. 3386 Freeport Road, Rockton, IL 61072 P.O. Box 750, Freeport, IL 610320 Phone: (815) 624-7459 Phone: (815) 235-2200 County: Winnebago County: Stephenson Mineral: Limestone Mineral: Limestone Wagner J. Quarry Schoonhoven Quarry Rees Construction Co., Inc Economy Excavating Co. 2918 Eleventh Avenue 1567 Heine Rd., Freeport, IL 610320 Monroe, WI 53566 Phone: (815) 235-4290 Phone: (608) 325-6819 County: Stephenson County: Stephenson Mineral: Limestone Mineral: Limestone Shiloh Quarry #125 Wayne Olesun Rockford Blacktop Construction 40001 N. Hoisington Road P.O. Box 2071, Loves Park, IL 61130 Pecatonica, IL 61063 Phone: (815) 654-4700 Phone: (815) 987-6432 County: Winnebago County: Winnebago Mineral: Limestone Mineral: Limestone Swalve Quarry 5751 West Florence Shannon, IL 610780 Phone: (815) 864-2268 County: Stephenson Mineral: Limestone

58 References

Berg, R.C., J.P. Kempton, and A.N. Stecyk, 1984, Geology for Planning in Boone and Winnebago Counties: Illinois State Geological Survey Circular 531, 69 p.

Krey, E, and J.E. Lamar, 1925, Limestone Resources of Illinois: Illinois State Geological Survey Bulletin 46, 392 p.

Lineback, J.A., 1979, Quaternary Deposits oflllinois: Illinois State Geological Survey 1:500,OOO-scale map.

Masters, J.M., 1983, Geology of Sand and Gravel Aggregate Resources of Illinois: Illinois State Geological Survey Illinois Mineral Notes 88, 10 p.

Samson, I.E., and J.M. Masters, 1992, Directory ofIllinois Mineral Producers 1992: lllinois State Geological Survey Illinois Minerals 109, 129 p.

59 Aquifer Delineation

An aquifer is a body of saturated earth materials capable of yielding sufficient groundwa­ ter to a or the intended use of a small-diameter well or large-diameter bored well. An aquifer will also yield water to any stream intercepting it. Aquifers in lllinois are com­ posed of water-saturated sand and gravel, fractured or jointed limestone and dolomite, or permeable sandstone. Fine grained earth materials such as silt, clay, shale, or till may restrict the flow of groundwater through and between aquifers.

Aquifer thicknesses and distributions tend to be most variable in glacial deposits. Sand and gravel aquifers are commonly found in the glacial drift where glacial meltwaters flowed over the landscape or in stream channels during and following successive advances and retreats of glacial ice. Although the bulk of the glacial drift is fine grained till, silt, and clay, sand and gravel may be the dominant lithology locally. Glacial drift aquifers are broadly categorized as basal, interbedded, and surficial.

The rock units making up the bedrock tend to be relatively uniform in character over wide areas horizontally and have their greatest variability in character in the vertical direction. In the Sugar-Pecatonica Assessment Area, bedrock aquifers are found in the shallow dolomites, the intermediate-depth dolomites and , and the deeply buried sand­ stones. Layers of shale and unfractured dolomite restrict the vertical movement of ground­ water between the bedrock aquifers.

Bedrock Aquifers

Considerable groundwater supplies can be obtained from the deep bedrock formations (of Cambrian and Ordovician age) within the Sugar-Pecatonica Assessment Area. These aquifers are commonly utilized throughout the area.

Moderate to large quantities of water can be obtained from the Mt. Simon Sandstone, with yields of more than 500 gallons per minute (gpm). The Ironton-Galesville Sandstones are generally even more productive and have expected yields in the 500 to 1,500+ gpm range.

Small to moderate, and in some places large, yields can be obtained from upper Cambrian and lower Ordovician rocks. Yields of as much as several hundred gpm can be obtained from the Ordovician Ancell Group rocks (St. Peter Sandstone), although 50 gpm is more common.

Where they are at or near the bedrock surface and are weathered, the dolomites of the Galena and Platteville Groups provide limited yields. Where they are protected by over­ lying rocks (Maquoketa and possibly Silurian), the lack of weathering generally renders

60 the Galena-Platteville generally "tight" and non-water yielding. In most of the area, the upper part of the Galena-Platteville is relatively well weathered because of its presence at the bedrock surface, and generally yields sufficient water for domestic purposes.

A limited yield of water can be obtained from the dolomite member of the Maquoketa where it composes the upper bedrock. Weathering of this dolomite layer (the Fort Atkinson Member) in the upper part of the Maquoketa can allow it to yield a small household (domes­ tic) supply. On the other hand, groundwater yields may be very limited in areas where the surficial bedrock is the Maquoketa shale.

Rocks of Silurian age overlie the Maquoketa in the southwest part of Stephenson County. The Silurian rocks can often yield adequate quantities (10 to 25 gpm locally) of water for domestic purposes in some areas where they are present at the bedrock surface in sufficient thickness.

Bedrock Groundwater Use

The public supply at Pecatonica is developed from the Ordovician Ancell Group (including the St. Peter Sandstone) and from the Cambrian Ironton and Galesville Formations at an approximate depth of 700 feet. A yield of 350 to 400 gpm is reported. The wells providing the Freeport public supply are approximately 500 feet deep, and develop their supplies from the Ordovician Ancell Group (St. Peter Sandstone). An unusually large yield of 1,500 to 2,000 gpm is available from the St. Peter Sandstone in this area.

A well drilled for the city of Winnebago originally yielded 40 gpm from the St. Peter Sand­ stone. This well was deepened and yielded 200 gpm from the Ironton-Galesville Sandstones. The public supply at Stockton is obtained from the Ironton-Galesville, as well as the Ancell. Some wells at Stockton were deepened from the Ancell to the Cambrian forma­ tions when the yield from the St. Peter Sandstone became inadequate.

Domestic supplies are generally obtained from drilled wells partially penetrating the Ancell (St. Peter Sandstone). Yields of 10 to 40 gpm are reported; much higher yields are available, but are not necessary for domestic supplies. These wells are generally 100 to 300 feet deep. Some wells develop a groundwater supply from the dolomites of the Galena­ Platteville Groups. These wells are usually shallower than 200 feet and yield adequate amounts for domestic purposes.

Bedrock Water Quality

Water quality in bedrock formations is governed by (l) the depth to the aquifer and (2) the extent to which the aquifer is confined, or covered by low-permeability layers. Confined aquifers may have their water recharge restricted (slowed) to such an extent that the ground­ water at depth can become considerably mineralized. Although confining beds are present, the bedrock aquifers in the Sugar-Pecatonica Assessment Area generally have less restricted recharge than those in areas to the south. Consequently, the groundwater generally has rela­ tively low levels of mineralization. In the assessment area, groundwater mineralization in­

61 creases with depth, but the deep bedrock formations in the area still yield usable, though somewhat mineralized, water. Water quality in the Ironton-Galesville is generally good: the total dissolved solid (TDS) content is less than 400 mglL, and in some places as low as 250 mgIL (Visocky and others 1985). Water quality in the middle and upper part of the Mt. Simon Sandstone is generally good, with TDS of 400 mgIL. The presence of radium may require additional water treatment. Water quality in the lower Mt. Simon can deterio­ rate rapidly, and the water may not be usable; but little information is available for that part of the formation.

TDS loads for the upper bedrock formations (Ordovician and Silurian) are even smaller, and the water obtained from all these formations is usable. Groundwater quality problems include increases in sulfates and chlorides, a general increase in TDS content, and the possi­ ble presence of radium in the Cambrian formations.

Glacial Drift Aquifers

Henry Formation

The primary glacial drift aquifers in the Sugar-Pecatonica Assessment Area are outwash deposits located in the floodplains of the Pecatonica and Sugar Rivers. These deposits (Henry Formation) can provide small to moderate yields; larger supplies are possibly avail­ able locally, particularly along the Pecatonica River floodplain at Freeport and toward the east. Thin, discontinuous deposits of the Henry Formation along minor stream valleys can provide small yields locally.

Additional Drift Deposits

Glacial deposits are present over the entire assessment area, but generally are thin. The upland areas are covered by deposits of till (primarily clay), interbedded locally with thin and discontinuous layers of sand and gravel that can provide limited yields. Such layers locally provide small water supplies, but in most parts of the assessment area, upland areas and slopes offer virtually no potential for a groundwater supply. The unconsolidated deposits in small buried bedrock valleys may contain deposits that locally can provide small to possibly moderate yields. Most domestic wells are developed in the shallow bedrock.

Glacial Drift Water Quality

The quality of water from glacial drift aqUifers is generally good, with relatively low total dissolved solids. The iron content of water obtained from Quaternary deposits is often rela­ tively high.

62 Summary

In summary, aquifers capable of reliably yielding moderate to large amounts of ground­ water are encountered only in the sandstone formations of Cambrian and Ordovician age, specifically the Cambrian Mt. Simon, the Ironton-Galesville Sandstones, and the Ancell (St. Peter Sandstone). Yields of several hundred gallons per minute are commonly available, and yields of 1,000 to 2,000 gallons per minute are available locally from the bedrock formations.

Outwash deposits (Henry Formation) within the Pecatonica River floodplain near and east of Freeport can provide moderate to large yields of groundwater. In parts of the Pecatonica floodplain, as well as the Sugar River floodplain, the Henry Formation can provide small to moderate yields. Discontinuous aquifers capable of yielding small to possibly moderate water supplies may be present locally in minor stream valleys. Only small yields may be locally obtained from drift aquifers over most of the rest of the assessment area.

Generally, public groundwater supplies are obtained almost exclusively from the bedrock (Cambrian and Ordovician) formations. Domestic water supplies are developed almost entirely from Ordovician rocks, the St. Peter Sandstone, and, to a small extent, the overly­ ing dolomites of the Galena-Platteville Groups. Only minor use is made of drift aquifers.

References

Berg, R.C., and J.P. Kempton, 1988, Stack-Unit Mapping of Geologic Materials in lllinois to a Depth of 15 Meters: Illinois State Geological Survey Circular 542, 23 p.

Berg, R.C., J.P. Kempton, and A.N. Stecyk, 1984, Geology for Planning in Boone and Winnebago Counties: Illinois State Geolgical Survey Circular 531, 69 p.

Csallany, S., 1966, Yields of Wells in Pennsylvanian and Mississippian Rocks in Illinois: Illinois State Water Survey Report of Investigation 55,43 p.

Csallany, S., and W. Walton, 1963, Yields of Shallow Dolomite Wells in Northern lllinois: Illinois State Water Survey Report of Investigation 46, 44 p.

Doyle, F.L., 1965, Geology of Freeport Quadrangle, Illinois: Illinois State Geological Survey Circular 395, 24 p.

Foster, J.W., 1956, Groundwater Geology of Lee and Whiteside Counties, lllinois: Illinois State Geological Survey Report of Investigation 194, 67 p.

Hackett, J.E., 1960, Groundwater Geology of Winnebago County, Illinois: Illinois State Geological Survey Report ofInvestigation 213, 63 p.

63 Hackett, J.E., and R.E. Bergstrom, 1956, Groundwater in Northwestern Illinois: Illinois State Geological Survey Circular 207, 25 p.

Hansel, A.K., and W.H. Johnson, 1996, Wedron and Mason Groups-Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area: Illinois State Geological Survey Bulletin 104, 116 p.; plate I: Quaternary Deposits of lllinois (map).

Herzog et aI., 1994, Buried Bedrock Surface of Illinois: Illinois State Geological Survey and U.S. Geological Survey, Illinois State Geological Survey Illinois Map 5.

Horberg, L., 1950, Bedrock Topography of Illinois: Illinois State Geological Survey Bulletin 73, III p.

Keefer, D.A., 1995, Potential for Agricultural Chemical Contamination of Aquifers in lllinois-1995 Revision: lllinois State Geological Survey Environmental Geology 148, 28p.

Kempton, J.P., 1963, Subsurface Stratigraphy of the Pleistocene Deposits of Central Northern lllinois: lllinois State Geological Survey Circular 356, 43 p.

Kolata, D.R., T.C. Buschbach, and J.D. Treworgy, 1978, The Sandwich Fault Zone in Northern Illinois: Illinois State Geological Survey Circular 505, 26 p.

Larson, T.H., A.M. Graese, and P.G. Orozco, 1993, Hydrogeology of the Silurian Dolomite Aquifer in Parts of Northwestern lllinois: lllinois State Geological Survey, Environmental Geology 145,29 p., 16 figs., 2 tables.

McGarry, C.S., 1997, Eight Maps Depicting Surficial Geologic Features in Carroll County, Illinois: Illinois State Geological Survey Open File Series 1997-13a-h; computer­ generated maps.

Nealon, J., J. Kirk, and A. Visocky, 1989, Regional Assessment of Northern Illinois Ground-water Resources: IlIinois State Water Survey Contract Report 473,83 p.

Nelson, W.J., 1995, Structural Features of Illinois: Illinois State Geological Survey Bulletin 100, 144 p.

Piskin, K., and R.E. Bergstrom, 1975, Glacial Drift in Illinois-Thickness and Character: lllinois State Geological Survey Circular 490, 35 p.

Public-Industrial-Commercial Supplies Database (PICS), 1996: Illinois State Water Survey.

Treworgy, J.D., 1981, Structural Features in Illinois-A Compendium: lllinois State Geological Survey Circular 519, 22 p.

64 Visocky, A.P., M.G. Sherrill, and K. Cartwright, 1985, Geology, Hydrology, Water Quality of the Cambrian and Ordovician Systems in Northern Illinois: Illinois State Geological and Water Surveys Cooperative GroundwaterlResources Report 10, 136 p.

Walton, W.C., and S. Csallany, 1962, Yields of Deep Sandstone Wells in Northern lllinois: lllinois State Water Survey Report of Investigation 43, 47 p.

Wehrmann, H.A., A.P. Visocky, B. Burris, R.R. Ringler, and R.D. Brower, 1980, Assessment of Eighteen Public Groundwater Supplies in Illinois: Illinois State Water Survey Contract Report 237, 185 p.

Willman, H.B., 1973, Rock Stratigraphy of the Silurian System in Northeastern and Northwestern Illinois: Illinois State Geological Survey Circular 479,55 p.

Willman, H.B., and J.C. Frye, 1970, Pleistocene Stratigraphy of Illinois: Illinois State Geological Survey, Bulletin 94, 204 p.

Willman, H.B., and D.R. Kolata, 1978, The Platteville and Galena Groups in Northern Illinois: Illinois State Geological Survey Circular 502, 75 p.

Willman, H.B., J.e. Frye, J.A. Simon, K.E. Clegg, D.H. Swann, E. Atherton, C. Collinson, J.A. Lineback, and T.C. Buschbach, 1967, Geologic Map oflllinois: Illinois State Geological Survey map.

Woller, D.M., and E.W. Sanderson, 1979, Public Groundwater Supplies in Carroll County: lllinois State Water Survey Bulletin 60-28, 23 p.

Woller, D.M., K.L. Kunz, and E.W. Sanderson, 1984, Public Groundwater Supplies in Stephenson County: Illinois State Water Survey Bulletin 60-30, 27 p.

65 Potential for Geologic Hazards

Detennining appropriate land use in the Sugar-Pecatonica Assessment Area requires an understanding of the potential natural and society-induced geologic hazards inherent to the area. Geologic hazards develop through interactions between geologic materials and natural forces and can be influenced by human activities. This section will sensitize read­ ers to some of the potential geologic hazards, including groundwater contamination, that can occur in the Sugar-Pecatonica Assessment Area. Site-specific geologic conditions or hazards are not comprehensively discussed. For a broader view of geologic hazards and what measures to take when they occur, consult Citizens' Guide to Geologic Hazards. Pre­ pared by the American Institute of Professional Geologists, this publication covers both hazards that arise from naturally occurring geologic materials (such as radon and asbes­ tos) and from geologic processes (such as earthquakes, landslides, and flooding). In addi­ tion, its appendices list sources of help from professional geologists and insurance professionals. The publication may be ordered by contacting:

American Institute of Professional Geologists 7828 Vance Drive Suite 103 Arvada, CO 80003 Telephone: (303) 431-0831

Potential for Contamination of Groundwater Resources

Groundwater contamination can arise from many sources. These sources are generally grouped into two classes, point or nonpoint, based on the size of the area where a chemi­ cal is applied or spilled, or a waste material is deposited. Point sources of contamination include many types of facilities and activities, such as landfills, chemical storage tanks (both above and below ground surface), individual septic systems, homeowner disposal of unwanted chemicals (for example, paint or used motor oil), the overapplication of lawn fertilizers and pesticides at individual residences, and the facilities of pesticide and fertilizer dealers or applicators, etc.

The primary nonpoint source of potential contamination in lllinois is the agricultural use of pesticides and fertilizers. Urban and suburban sources of groundwater contamination, such as septic systems and overuse of lawn fertilizers and pesticides, can also become nonpoint problems if a significant concentration of these sources occurs in a subdivision or other area.

Groundwater contamination can be defined as the presence of a chemical at or below the water table in concentrations that exceed federal or state acceptable levels. Flowing

66 groundwater is the means of transporting these dissolved contaminants away from their source. Responsible chemical use and prompt cleanup of spills can prevent the degrada­ tion or contamination of groundwater. In addition, it can be helpful to restrict or closely monitor activities that can contribute to groundwater contamination, particularly when they are conducted in or near the setback zone of a water supply well. The Illinois EPA provides information on the delineation of setback zones and the evaluation of activities within these areas (Cobb and others 1995).

The potential for groundwater contamination depends on a complicated combination of hydrogeologic properties, environmental processes, and the quantity and nature of the contaminant in question. In general, as depth to the top of the uppermost aquifer increases, the sensitivity to contamination of that particular aquifer decreases. Greater depth from the ground surface affords an aquifer greater protection, due to the increased opportunity for adsorption, microbial degradation, and dilution of a spilled contaminant before it can reach the aquifer. The validity of this statement, however, depends on several other factors. The effects of these various factors on contaminant fate and transport are discussed below.

Effects of Climatic Variables on the Fate of the Contaminant

Four climatic variables (precipitation, temperature, humidity, and wind speed) help deter­ mine the fate of subsurface chemicals through their impact on several different processes. The amount and intensity of rain helps to determine the amount of runoff from the soil surface and, consequently, the amount of water infiltrating the soil surface. Temperature, humidity, and wind speed influence water and chemical movement through their effects on the processes of evaporation, transpiration, volatilization, and condensation.

Evaporation of water from the soil and transpiration of water from plants both reduce the amount of water in the soil that percolates downward to the water table. Depending on the depth of the water table and the depth and distribution of plant roots, plants can even remove water from below the water table.

Volatilization is the process whereby a chemical in a liquid state is heated enough to con­ vert it to a gaseous state. Gasoline is one example of a chemical that can volatilize at tem­ peratures normally found in the soil during Illinois summers. Condensation is the process whereby gaseous chemicals are cooled into a liquid state. Once condensed, the chemical may become dissolved in water and leach to the groundwater system. Thus, chemicals that have been volatilized and remain trapped as gases in soil can condense back to a liquid form and leach to groundwater.

Effects of Quantity and Chemical Characteristics on the Fate of the Contaminant

The quantity and nature of a chemical spill or application, as well as the chemical proper­ ties of the contaminant, also help determine whether groundwater contamination will occur and the amount of groundwater that will become contaminated. The larger the quantity of contaminant that is released, the more likely it is that some fraction of the chemical will leach to groundwater. In addition, the depth from the land surface to the

67 aquifer and the area of land exposed to the chemical will also affect the likelihood of ground­ water contamination. For example, a herbicide applied to the land surface at a rate of 3 pounds per acre over 640 acres will have a much lower likelihood of causing significant ground­ water contamination than a leaking gasoline storage tank that is 15 feet below land surface.

Several chemical properties affect the fate of a chemical in the subsurface. These proper­ ties include, but are not limited to, water solubility (the amount of a chemical that can dissolve in water) and the adsorption coefficient (a measure of the tendency for a chemi­ cal to stick to the outside of soil particles). Many chemicals applied to agricultural fields are removed by runoff and soil erosion during rainfalls. The water solubility of a chemi­ cal helps control how readily the chemical mixes, or dissolves, in water. Less-soluble compounds will generally not move as rapidly as more-soluble compounds. Adsorption is the process whereby a molecule of a chemical sticks to the surface of a soil particle. Like solubility, adsorption is important in helping to control the rate of chemical movement in the subsurface. Many organic chemicals found in pesticides or used in solvents are strongly adsorbed by the organic matter or clay minerals in soil, which slows their flow to ground­ water resources. Nitrate, however, does not adsorb to soil particles, and so moves much more rapidly in groundwater than do pesticides.

In addition to solubility and adsorption characteristics, potential contaminants are also characterized by their half-life. The half-life of a chemical is a measure of the speed with which it can be degraded by microbial organisms or by exposure to other natural processes. In general, these processes break the chemical down into smaller compounds that may be less toxic or even nontoxic.

Effects of Geologic Materials

Whether groundwater becomes contaminated also depends heavily upon the hydro­ geologic characteristics of the area. Groundwater flow is largely controlled by the hydraulic conductivity of the geologic materials and the hydraulic gradient of the system. Hydraulic conductivity is a measure of the ability of water to flow through a geologic deposit. For example, sand and gravel deposits generally have high hydraulic conductivity values, whereas clayey diamictons generally have low hydraulic conductivity values. Some geo­ logic materials are fractured, and depending on the size and spacing of the fractures, hydraulic conductivities in these units can be much higher than unfractured materials.

Hydraulic gradient is the difference in groundwater pressure between two points. Under a large hydraulic gradient (or a large difference in pressure), water and dissolved con­ taminants will move more quickly through a given geologic material than under a small hydraulic gradient.

Because the measurement of hydraulic conductivity and hydraulic gradient requires signifi­ cant commitments of time and money, other methods have been developed to estimate the potential for groundwater contamination.

68 Potential for Groundwater Contamination

Most discussions of groundwater contamination do not distinguish between groundwater contamination and aquifer contamination. This distinction can have very important prac­ tical consequences. Technically, any time a chemical leaches into the water table to a concentration above a level established by a state or federal agency, groundwater is con­ taminated. In most of lllinois, however, contamination of shallow groundwater would not necessarily result in contamination of the uppermost aquifer because the uppermost aqui­ fer commonly lies deeper than 20 feet from the surface. Most water supplies that use groundwater rely on the water in aqUifers for that supply. For this reason, most concerns regarding groundwater quality generally refer to the protection of the water quality in aquifers rather than all groundwater.

In regions without aquifers, private water supplies may have to draw water from non­ aquifer materials with low hydraulic conductivities by using large-diameter dug or bored wells. Residents of these regions must be concerned with the contamination of any ground­ water.

The contamination potential of shallow aquifers is estimated using information on the occurrence and depth of shallow sand and sand and gravel deposits, and on the leaching characteristics of mapped soils (Keefer 1995). It is important to recognize that, by defini­ tion, aquifers are geologic deposits that are saturated with water. Sand and gravel deposits may not be aquifers when they are saturated only partially or seasonally. The statewide pre­ diction of contamination potential by Keefer (1995) recognized these factors, but noted that the relative contaminant transport properties of aquifer and nonaquifer materials did not change significantly when the materials were unsaturated. For this reason, all mapped deposits of aquifer material (that is, sand, sand and gravel, fractured limestone or dolomite, and sandstone) were treated as aquifers by Keefer (1995), and are treated similarly in this discussion.

To create the aquifer sensitivity map of the assessment area (Figure 25), the soils of the assessment area were first classified according to their predicted pesticide leaching characteristics (Keefer 1995). Soils with greater organic-matter contents were generally classified as having lower leaching potential (greater ability to retain contaminants and prevent aquifer contamination) than soils with smaller organic-matter contents. In addi­ tion, soils with smaller hydraulic conductivities or poor drainage characteristics were classified as having lower leaching potential than soils with larger hydraulic conductivi­ ties and better drainage.

These aquifer sensitivity classifications are based only on the generalized characteristics of the mapped geologic materials. Water quality information was not used because no suit­ able information was available. This map (Figure 25) was designed to be used for state­ wide screening purposes. These limitations should be considered, however, before using the aquifer sensitivity interpretations for anything other than broad screening decisions at the assessment area or subbasin level.

69 ._-. )

Excessive Somewhat Limited Disturbed landl o 5 10 15 20 GLJ r I ~ I surlace water Miles High G::J limited -- assessment area ...- - boundary l!Oj Moderate o Very Limited I county boundary ~ N I

Figure 25. Aquifer Sensitivity to Contamination by Pesticide Leaching (Keefer 1995) Aquifer Contamination Potential in the Sugar-Pecatonica Assessment Area

Aquifer sensitivity to contamination from pesticide leaching has been evaluated for lllinois (Keefer 1995), and the map for the Sugar-Pecatonica Assessment Area is presented in Figure 25. Approximately 76% of the 509,000 acres of land in this assessment area has been mapped as having an aquifer sensitivity to contamination of Moderate or above. Approximately 15% of the area is mapped as having a Very Limited aquifer sensitivity, whereas, the Somewhat Limited and Limited categories occupy approximately 7% and 1% of the land area, respectively.

A detailed examination of Figure 25 suggests that areas having Excessive aquifer sensitivity are the most abundant in the assessment area, occupying over 176,000 acres. These areas occur along the sloping uplands surrounding the Pecatonica and Sugar Rivers, where the uppermost aquifer material is generally within 20 feet of land surface (Keefer 1995). Because of the tendency for surface waters to travel downslope rather than downwards into the soil, the soil leaching characteristics of these areas have been rated as Moderate (Keefer 1995) with regard to the potential for pesticide leaching. The soils are formed in geologic materials that generally consist of a thin mantle of windblown silt (loess) over­ lying a sandy glacial till (Berg and Kempton 1988, Ray and others 1976, Grantham 1980).

Areas of High aquifer sensitivity are mapped in over 134,000 acres of the assessment area and are located throughout all but the southeastern part of the assessment area. The geologic sequences of these areas include a thin covering of windblown silt overlying a sandy glacial till (Berg and Kempton 1988, Ray and others 1976, Grantham 1980). Because these areas generally have aquifer materials within 20 feet of land surface (Keefer 1995), they have received a High aquifer sensitivity rating despite the fact that the soils in these areas have been classified as having Somewhat Limited or Limited pesticide leaching characteristics (Keefer 1995).

Areas with Moderate aquifer sensitivity occur in over 78,000 acres of this assessment area. In the north half of the assessment area, most areas with Moderate sensitivity occur where aquifer materials are commonly within 20 feet of land surface. These areas are generally located in the uplands of the Pecatonica River, where the slopes are gentle and the soils are poorly drained. Keefer (1995) classified the soils in these areas as having Very Lim­ ited pesticide leaching characteristics. In the eastern part of the assessment area, Moder­ ate aquifer sensitivity areas are found where the uppermost aquifer is deeper, generally between 20 and 50 feet from land surface. In these settings, the soil leaching characteris­ tics were classified as Moderate (Keefer 1995) primarily because of a reduction in organic matter and an increase in the drainage capacity of these soils, relative to those with Very Limited leaching characteristics.

The Somewhat Limited aquifer sensitivity category is mapped over 34,000 acres of the assessment area. These areas are generally found in the Yellow Creek subbasin, in the southeastern part of the assessment area. The depth to the uppermost aquifer material in these areas generally ranges from 20 to 50 feet from land surface (Keefer 1995). The soil leaching characteristics are primarily classified as Very Limited (Keefer 1995). This

71 soil leaching classification is due to the high organic-matter content of these soils (Ray and others 1976, Keefer 1995).

The Limited aquifer sensitivity category was mapped in just over 6,000 acres of the Sugar-Pecatonica Assessment Area. Limited aquifer sensitivity occur in areas character­ ized by Excessive or High soil leaching characteristics and no mapped aquifer material within 50 feet of land surface. These areas generally occur along the slopes of the Sugar and Pecatonica River valleys, where no aquifer materials generally occur within 50 feet of land surface; but Excessive or High soil leaching characteristics suggest that the soils are very well drained and have relatively low organic-matter contents (Ray and others 1976, Keefer 1995).

The Very Limited aquifer sensitivity category is found over approximately 79,000 acres of the Sugar-Pecatonica Assessment Area. In general, these areas are characterized by Moderate to Very Limited soil leaching characteristics and no mapped aquifer material within 50 feet of land surface (Keefer 1995). In the southern part of the assessment area, Very Limited aquifer sensitivity areas are found in the Yellow Creek subbasin, where the glacial tills or modem river deposits are over 50 feet thick. The other major region of Very Limited aquifer sensitivity is along most of the Pecatonica River floodplain and adjacent sloping uplands. These areas are also characterized by thick sequences of river deposits and glacial tills (Berg and Kempton 1988) and generally have soils with Very Limited leaching characteristics (Keefer 1995).

Regional Earthquake Activity

People staggered as if drunk through the streets of Beloit where the buildings rocked vio­ lently. A runaway streetcar was sent rolling down a hill in Rockford. Chimneys toppled in Mt. Carroll, cement walkways cracked open in Freeport, and streets in entire towns filled with excited, frightened citizens. These are not scenes from a TV show or Hollywood disaster movie, but descriptions of the effects from a magnitude 5.1 earthquake that shook northern Illinois and southern Wisconsin on May 26, 1909.

Many people might be surprised to learn that small earthquakes, ranging from magnitude 3.0 to 5.0, occur about once every 20 years somewhere in northern Illinois. These small earthquakes are felt in the Sugar-Pecatonica Assessment Area and occasionally cause minor damage. Larger earthquakes in the more seismically active regions of , Missouri, and Tennessee can also shake the area.

The 1909 earthquake is probably the most notable of these small northern Illinois earth­ quakes of this century. No seismometers were available to accurately report the magni­ tude and location of this earthquake, but on the basis of reports of what people felt, it apparently was centered in eastern Ogle County and probably measured about 5.1 on the Richter scale. This earthquake was widely felt in the Midwest. Many people were fright­ ened and schools were closed. Several other moderate-sized earthquakes have caused

72 minor damage in northern Illinois in this century. These magnitude 4.5 to 5 quakes were strong enough to alarm many residents in the area and were felt in neighboring states as well. They appear to represent the upper limit on earthquake size that can be expected in the area and represent a minor hazard to the area.

More typical of northern Illinois earthquakes are the two magnitude 3 to 3.5 earthquakes that have been reported in the Sugar-Pecatonica Assessment area (Figure 26). These earth­ quakes are generally only felt within a 5 to 10 mile radius of the epicenter, and in that region they rarely cause even minor damage. Slightly stronger earthquakes, with a magni­ tude of 3.5 to 4.5, are generally felt over larger distances, particularly when they occur at night. They often frighten people but rarely cause damage. For instance, the magnitude 3.5 earthquake reported in 1928 just south of the assessment area in Carroll County occurred at 3:30 in the morning. It was felt in northern Illinois and eastern . The frightened citi­ zens of Mt. Carroll called out the home guard believing a bank was being robbed.

There are so few earthquakes in the region that it is difficult to find the faults that cause them. The few earthquakes that have been reported do not appear to be related to any known geologic feature.

The Seismic Zone, about 300 miles to the southeast, spawns magnitude 5 earthquakes about every 10 years. A magnitude 5.0 earthquake in 1987 and a magnitude 5.2 earthquake in 1968 were felt in the Sugar-Pecatonica Assessment Area by people indoors, but generally not felt by people who were outdoors at the time. The Wabash Valley area could produce earthquakes as great as Richter magnitude 6.5. These larger quakes might cause damage to chimneys and older brick structures in the Sugar-Pecatonica Assess­ ment Area, but the likelihood of their occurring in the near future is very low.

The New Madrid Seismic Zone in far southern lllinois, Missouri, and Tennessee is capa­ ble of producing very powerful earthquakes; but because it is over 400 miles to the south, the resulting ground motions in the Sugar-Pecatonica Assessment Area are not expected to be dangerous. The last major earthquake in the New Madrid Seismic Zone occurred on October 31,1895. This magnitude 6.2 earthquake caused severe damage in southern lllinois towns. In northern Illinois, the passing of the seismic waves issued an early (5:00 A.M.) wake-up call to residents from Rock Island to . Window glass and china were broken in Rockford, where guests at hotels were thrown into panic; but no one was hurt, and no serious damage was reported. Slight earthquake waves were noticed in the larger buildings of Freeport, but again, no serious damage was done. A similar earthquake, with similar effects, is expected to occur in the New Madrid Seismic Zone sometime in the next 15 years.

An even stronger series of earthquakes occurred in the New Madrid Seismic Zone in 1811-1812. Devastating earthquakes, probably as great as Richter magnitude 8 occurred three times that winter. There is no record of the ground motions in the Sugar-Pecatonica Assessment Area from those earthquakes, but it is estimated that the motions would proba­ bly have been strong enough to damage masonry structures. Fortunately, such large earthquakes are not expected to recur within the next several hundred years.

73 ..., --1 '-'.

1 I 1 I I 1

1 1912 I ~I 3.8 • 1 !!!I I ~ 1 0 1 ...,01 I ______L _ 1

CAR' 1 BOONE 1 ______-.L __ .:... L -­

: DEKALB I o'" I ~ I i I 1928 1909 1 3.5 • 5.1. I 1804 1

1 4~ 1 ------wffilliIDE' I r- Ii----L~ ,l).,r- ~ 1 1 I 1 1913 I 1 3.9. 1 I 1 I 1909 1 I > 4.0 I 1

5 10 15 20 25 o, i county boundary • epi center _ Sugar-Pecatonica Miles Assessment Area 119121 year of earthquake assessment boundary ! em approximate magnitude state boundary 1 Figure 26. Earthquakes in the Vicinity of the Sugar-Pecatonica Assessment Area (St. Louis University Earthquake Center database 1996) References

Berg, RC., and J.P. Kempton, 1988, Stack-Unit Mapping of Geologic Materials in lllinois to a Depth of 15 Meters: Illinois State Geological Survey Circular 542, 23 p.

Cobb, R.P., H.A.Wehnnann, and RC. Berg, 1995, Guidance Document for Groundwater Protection Needs Assessments: Illinois Environmental Protection Agency, Report No. IEPNPWS/95-0l, 96 p.

Grantham, D.R., 1980, Soil Survey of Winnebago and Boone Counties, Illinois: U.S. Department of Agriculture, in cooperation with the Illinois Experiment Station, 279 p.

Keefer, D.A., 1995, Potential for Agricultural Chemical Contamination of Aquifers in Illinois-1995 Revision: Illinois State Geological Survey Environmental Geology 148,28 p.

Nuhfer, E.B., RJ. Proctor, and P.H. Moser, 1993, Citizens' Guide to Geologic Hazards: American Institute of Professional Geologists, Arvada, CO, 134 p.

Ray, B.W., J.B. Fehrenbacher, R. Rehner, and L.L. Acker, 1976, Soil Survey: Stephenson County, Illinois: University of Illinois Agricultural Experiment Station, in cooperation with the U.S. Department of Agriculture, Soil Report 99, 133 p.

75 Appendix A: Overview of Databases

Illinois Wetlands Inventory This digital database contains the location and classification of wetland and deepwater habitats in lllinois. Following U.S. Fish and Wildlife Service definitions, the lllinois Natural History Survey (INHS) compiled the information from interpretations of I:58,000-scale high-altitude photographs taken between 1980 and 1987. Identifiable wetlands and deepwater habitats were represented by points, lines, and polygons on 1:24,OOO-scale U.S. Geological Survey (USGS) 7.5- minute quadrangle maps. These data were digitized and compiled into the lllinois Wetlands Inventory. Because no wetland or deep-water habitats smaller than 0.01 acres were included, many farmed wetlands are not in the database. This database is appropriate for analysis on a local and regional scale; due to the dynamics of wetland systems, however, boundaries and classifications may change over time. For detailed explanation of wetland classification in Illinois, see Wetland Resources of Illinois: An Analysis and Atlas (Suloway and Hubbell 1994).

Quaternary Deposits of Illinois Originally automated in 1984, this database is the digital representation of the 1:500,OOO-scale map Quaternary Deposits in Illinois (Lineback 1979). Because these data, modified by Hansel and Johnson (1996), represent a generalization of the glacial sediments that lie at or near the land surface, this database is most appropriate for use at a regional scale. For further information about surficial deposits in Illinois, see Wedron and Mason Groups: Lithostratigraphic Reclassification ofthe Wisconsin Episode, Lake Michigan Lobe Area (Hansel and Johnson 1996).

Thickness of Loess in Illinois This database contains 5-foot-interval contour lines indicating loess thickness on uneroded upland areas in Illinois. These data were originally automated in 1986 from the 1:500,OOO-scale map in Glacial Drift in Illinois-Thickness and Character (Piskin and Bergstrom 1975, plate 1). This database is most appropriate for use at a regional scale.

Thickness of Surficial Deposits This database contains polygons delineating glacial and stream materials throughout the state, with thicknesses ranging from less than 25 feet to greater than 500 feet. The data were originally automated in 1986 from the 1:500,OOO-scale map in Glacial Drift in Illinois-Thickness and Character (Piskin and Bergstrom 1975, plate I). This database is most appropriate for use at a regional scale.

Noncoal Mineral Industry Database Compiled by the ISGS from lllinois Office of Mines and Minerals permit data and informa­ tion from the ISGS Directory of Illinois Mineral Producers, this database contains the locations of mineral extraction operations (other than coal, oil, and gas producers) in

76 Illinois. The database contains both active and inactive sites and is updated every year. The 1996 data include 7 active underground mines and 449 active surface pits and quarries. This is a point database and is appropriate for analysis on a local to regional scale. For more information on the current locations of noncoal mineral extraction sites or on the location of potential noncoal mineral resources, contact the Industrial Minerals Section of the Illinois State Geological Survey.

1:100,OOO-Scale Topography ofl1Iinois Depicting the general configuration and relief of the land surface in Illinois, this database was compiled by the ISGS from 1: 100,OOO-scale digital line graph (DLG) format data files, originally automated by the USGS from USGS 1:100,OOO-scale 30- by 60-minute quadrangle maps. The USGS collected the land surface relief data for Illinois from stable­ base manuscripts, photographic reductions, and stable-base composites of the original 1: 100,000 map separates using manual, semiautomatic, and automatic digitizing systems. The contour interval of this topographic data is 5.0 meters (16.4 feet). These digital data are useful for the production of intermediate- to regional-scale base maps and for a variety of spatial analyses, such as determining the slope of a geographic area. DLG format topo­ graphic data are available from the USGS and can be down loaded on the Internet from

http://edcwww.cr.usgs.gov/glis/hyper/guide/lOOkdlgfiglstatesffl.html

A full description of the DLG format can be found in the Digital Line Graphs from l:lOO,OOO-Scale Maps-Data Users Guide 2 produced by the USGS. These data are also available from the ISGS in ARC format.

State Soil Geographic (STA TSGO) Data Base for Illinois The Illinois STATSGO was compiled by the USDA Natural Resources Conservation Service (NRCS). The database is the result of generalizing available county-level soil surveys into a general soil association map. Ifno county survey was available, data on geology, topography, vegetation, and climate were assembled along with Land Remote Sensing Satellite (LANDSAT) images. Soils of like areas were studied, and the probable classification and extent of the soils were determined. The data were compiled at 1:250,000-scale using USGS 1- by 2- degree quadrangle maps. This database was designed to be used primarily for regional, multistate, state, and river basin resource planning, management, and monitoring. It is not intended to be used at the county level. Illinois STATSGO data are available in DLG, ASCn, or ARC format and can be down­ loaded on the Internet from

http://www.gis.uiuc.edu/nrcs/soil.htrnl

The data are also available from the ISGS in ARC format. For more information visit the USDA web site or contact the Natural Resources Conservation Service, 1902 Fox Drive, Champaign, IL 61820.

77 Land Cover Database of Illinois Compiled for the IDNR Critical Trends Assessment Project by the INHS, the land cover database is intended as a base line for assessment and management of biologic natural resources in Illinois. Twenty-three major land cover classes were defined using Thematic Mapper (TM) Satellite data. Dates of the imagery range from April 1991 to May 1995. Ancillary data used to interpret the TM imagery include the 1992 Topologically Integrated Geographic Encoding and Referencing System (TIGER) line files, the Illinois Wetlands Inventory, NRCS county crop compliance data, 1988 National Aerial Photography Program (NAPP) photography, and USGS transportation and hydrography data. This database is most appropriate for use at medium and regional scales. For more information on land cover in Illinois see Illinois Land Cover-An Atlas (Illinois Department of Natural Resources 1996).

References

Hansel, AK., and W.H. Johnson, 1996, Wedron and Mason Groups-Lithostratigraphic Reclassification of Deposits of the Wisconsin Episode, Lake Michigan Lobe Area: Illinois State Geological Survey Bulletin 104, 116 p.; plate 1, Quaternary Deposits of llIinois. Revised map. llIinois Land Cover-An Atlas, 1996: Illinois Department of Natural Resources, Springfield, llIinois, IDNRlEEA-96/05, 157 p.

Lineback, I.A., compiler, 1979, Quaternary Deposits of Illinois: llIinois State Geological Survey 1:500,000 scale map.

Piskin, K., and R.E. Bergstrom, 1975, Glacial Drift in Illinois-Thickness and Character: Illinois State Geological Survey Circular 490, 35 p.

Suloway, L., and M. Hubble, 1994, Wetland Resources of llIinois-An Analysis and Atlas: Illinois Natural History Special Publication 15,88 p.

78 Appendix B. Principal Land Cover of the Sugar-Pecatonica Assessment Area

Yellow Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 114,826 92.3 22.5 Cropland 76,952 61.8 15.1 Rural Grassland 37,874 30.4 7.4 Forest and Woodland 4,220 3.4 0.8 Urban and Built-Up Land 3,676 3.0 0.8 UrbanlBuilt-Up 1,818 1.5 0.4 Urban Grassland 1,858 1.5 0.4 Wetland 637 0.5 0.1 Forested 364 0.3 0.1 Nonforested 273 0.2 0.0 Other Land 1,067 0.8 0.2 Lakes and Streams 1,013 0.8 0.2 Barren and Exposed 54 0.0 0.0 Total 124,427 100.0 24.4

Waddams Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 10,613 79.9 2.1 Cropland 4,501 33.9 0.9 Rural Grassland 6,112 46.0 1.2 Forest and Woodland 1,845 13.9 0.4 Urban and Built-Up Land 560 4.2 0.1 UrbanlBuilt-Up 260 2.0 0.0 Urban Grassland 300 2.3 0.1 Wetland 97 0.7 0.0 Forested 61 0.5 0.0 Nonforested 36 0.3 0.0 Other Land 172 1.3 0.0 Lakes and Streams 169 1.3 0.0 Barren and Exposed 3 0.0 0.0 Total 13,286 100.0 2.6

79 East Branch Richland Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 3,394 94.6 0.7 Cropland 2,285 63.7 0.4 Rural Grassland 1,109 30.9 0.2 Forest and Woodland 166 4.6 0.0 Wetland o 0.0 0.0 Forested o 0.0 0.0 Other Land 26 0.7 0.0 Lakes and Streams 26 0.7 0.0 Total 3,586 100.0 0.7

Richland Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 23,538 90.4 4.6 Cropland 11,522 44.3 2.3 Rural Grassland 12,015 46.2 2.4 Forest and Woodland 831 3.2 0.2 Urban and Built-Up Land 379 1.5 0.1 UrbanlBuilt-Up 280 1.1 0.0 Urban Grassland 99 0.4 0.0 Wetland 807 3.1 0.2 Forested 312 1.2 0.1 Nonforested 495 1.9 0.1 Other Land 473 1.8 0.1 Lakes and Streams 473 1.8 0.1 Total 26,028 100.0 5.2

80 Cedar Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 19,854 94.3 3.9 Cropland 11,909 56.6 2.3 Rural Grassland 7,945 37.7 1.6 Forest and Woodland 629 3.0 0.1 Urban and Built-Up Land 271 1.3 0.1 UrbanlBuilt-Up 133 0.6 0.0 Urban Grassland 138 0.6 0.0 Wetland 81 0.4 0.0 Forested 6 0.0 0.0 Nonforested 75 0.4 0.0 Other Land 221 1.0 0.0 Lakes and Streams 217 1.0 0.0 Barren and Exposed 5 0.0 0.0 Total 21,056 100.0 4.1

Rock Run Subbasin Category Acres % Subbasin % Area Agricultural Land 31,595 91.6 6.2 Cropland 17,705 51.4 3.5 Rural Grassland 13,890 40.3 2.7 Forest and Woodland 1,736 5.0 0.3 Urban and Built-Up Land 416 1.2 0.1 UrbanlBuilt-Up 241 0.7 0.0 Urban Grassland 175 0.5 0.0 Wetland 349 1.0 0.1 Forested 232 0.7 0.1 Nonforested 117 0.3 0.0 Other Land 383 1.1 0.1 Lakes and Streams 383 1.1 0.1 Total 34,480 100.0 6.7

81 Lost Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 8,588 94.3 1.7 Cropland 4,744 52.1 0.9 Rural Grassland 3,844 42.2 0.8 Forest and Woodland 165 1.8 0.0 Urban and Built-Up Land 258 2.8 0.0 UrbanlBuilt-Up 149 1.6 0.0 Urban Grassland 108 1.2 0.0 Wetland 14 0.2 0.0 Forested 1 0.0 0.0 Nonforested 13 0.1 0.0 Other Land 79 0.9 0.0 Lakes and Streams 79 0.9 0.0 Total 9,104 100.0 1.7

North Branch Otter Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 10,490 86.7 2.0 Cropland 7,845 64.8 1.5 Rural Grassland 2,644 21.8 0.5 Forest and Woodland 1,248 10.3 0.2 Urban and Built-Up Land 200 1.6 0.0 UrbanlBuilt-Up 56 0.5 0.0 Urban Grassland 144 1.2 0.0 Wetland 46 0.4 0.0 Forested 1 0.0 0.0 Nonforested 45 0.4 0.0 Other Land 121 1.0 0.0 Lakes and Streams 113 0.9 0.0 Barren and Exposed 8 0.1 0.0 Total 12,104 8,100.0 2.2

82 South Branch Otter Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 10,189 81.0 2.0 Cropland 6,407 51.0 1.3 Rural Grassland 3,782 30.1 0.7 Forest and Woodland 697 5.5 0.1 Urban and Built-Up Land 1,264 10.0 0.2 UrbanIBuilt-Up 358 3 0.0 Urban Grassland 905 7.2 0.2 Wetland 39 0.3 0.0 Forested 10 0.1 0.0 Nonforested 29 0.2 0.0 Other Land 387 3.1 0.1 Lakes and Streams 387 3.1 0.1 Barren and Exposed 5 0.0 0.0 Total 12,581 100.0 2.4

Otter Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 3,591 88.9 0.7 Cropland 2,110 52.2 0.0 Rural Grassland 1,482 36.7 0.3 Forest and Woodland 191 4.7 0.0 Urban and Built-Up Land 5 0.1 0.0 UrbanlBuilt-Up 5 0.1 0.0 Wetland 198 4.9 0.0 Forested 124 3.1 0.0 Nonforested 73 1.8 0.0 Other Land 53 1.3 0.0 Lakes and Streams 53 1.3 0.0 Total 4,039 100.0 0.7

83 Pink Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 10,024 93.3 2.0 Cropland 5,876 54.7 1.2 Rural Grassland 4,148 38.6 0.8 Forest and Woodland 445 4.1 0.1 Wetland 123 1.2 0.0 Forested 81 0.8 0.0 Nonforested 42 0.4 0.0 Other Land 148 1.4 0.0 Lakes and Streams 148 1.4 0.0 Total 10,739 100.0 2.1

Sumner Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 22,756 95.9 4.5 Cropland 15,759 66.4 3.1 Rural Grassland 6,997 29.5 1.4 Forest and Woodland 390 1.6 0.1 Urban and BUilt-Up Land 167 0.7 0.0 UrbanIBuilt-Up 150 0.6 0.0 Urban Grassland 17 0.1 0.0 Wetland 248 1.1 0.0 Forested 165 0.7 0.0 Nonforested 83 0.4 0.0 Other Land 165 0.7 0.0 Lakes and Streams 165 0.7 6.0 Total 23,726 100.0 4.6

84 Coolidge Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 10,053 91.0 2.0 Cropland 6,431 58.2 1.3 Rural Grassland 3,622 32.8 0.7 Forest and Woodland 165 1.5 0.0 Urban and Built-Up Land 355 3.2 0.0 UrbanlBuilt-Up 208 1.9 0.0 Urban Grassland 147 1.3 0.0 Wetland 358 3.2 0.1 Forested 78 0.7 0.0 Nonforested 280 2.5 0.0 Other Land 116 1.0 0.0 Lakes and Streams 116 1.0 0.0 Total 11,047 100.0 2.1

Rhule Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 2,445 96.2 0.5 Cropland 1,544 60.8 0.3 Rural Grassland 901 35.4 0.2 Forest and Woodland 49 1.9 0.0 Wetland 47 1.9 0.0 Forested 29 1.2 0.0 Nonforested 18 0.7 0.0 Other Land 1 0.0 0.0 Lakes and Streams 1 0.0 0.0 Total 2,542 100.0 0.5

85 Sugar River Subbasin Category ,Acres % Subbasin % Area Agricultural Land 11,581 77.0 2.3 Cropland 6,724 44.7 1.3 Rural Grassland 4,858 32.3 1.0 Forest and Woodland 1,178 7.8 0.2 Urban and Built·Up Land 104 0.7 0.0 UrbanlBuilt-Up 104 0.7 0.0 Wetland 1,978 13.2 0.4 Forested 1,514 10.1 0.3 Nonforested 464 3.1 0.1 Other Land 193 1.3 0.0 Lakes and Streams 193 1.3 0.0 Total 15,034 100.0 3.9

Raccoon Creek Subbasin Category Acres % Subbasin % Area Agricultural Land 7,463 76.2 1.5 Cropland 3,505 35.8 0.7 Rural Grassland 3,957 40.4 0.8 Forest and Woodland 821 8.4 0.2 Urban and Built·Up Land 179 1.8 0.0 UrbanIBuilt-Up 48 0.5 0.0 Urban Grassland 131 1.3 0.0 Wetland 1,256 12.8 0.3 Forested 353 3.6 0.1 Nonforested 903 9.2 0.2 Other Land 73 0.8 0.0 Lakes and Streams 73 0.8 0.0 Total 9,792 100.0 2.0

86 Pecatonica River (upper) Subbasin Category Acres % Subbasin % Area Agricultural Land 56,130 92.0 11.1 Cropland 29,318 48.1 5.8 Rural Grassland 26,812 44.0 5.3 Forest and Woodland 2,549 4.2 0.5 Urban and Built-Up Land 521 0.9 0.1 UrbanlBuilt-Up 295 0.5 0.1 Urban Grassland 225 0.4 0.0 Wetland 688 1.1 0.2 Forested 374 0.6 0.1 Nonforested 313 0.5 0.1 Other Land 1,102 1.8 0.2 Lakes and Streams 1,101 1.8 0.2 Barren and Exposed 2 0.0 0.0 Total 60,990 100.0 12.1

Pecatonica Creek (upper middle) Subbasin Category Acres % Subbasin % Area Agricultural Land 18,676 71.5 3.7 Cropland 10,029 38.4 2.0 Rural Grassland 8,648 33.1 1.7 Forest and Woodland 1,332 5.2 0.3 Urban and BUilt-Up Land 4,482 17.1 0.9 UrbanlBuilt-Up 3,116 11.9 0.6 Urban Grassland 1,365 5.2 0.3 Wetland 896 3.5 0.2 Forested 561 2.2 0.1 Nonforested 335 1.3 0.1 Other Land 714 2.7 0.1 Lakes and Streams 685 2.6 0.1 Barren and Exposed 29 0.1 0.0 Total 26,100 100.0 5.0

87 Pecatonica Creek (middle) Subbasin Category Acres % Subbasin % Area Agricultural Land 28,831 87.9 5.6 Cropland 17,899 54.6 3.5 Rural Grassland 10,932 33.3 2.1 Forest and Woodland 1,237 3.8 0.2 Urban and Built-Up Land 304 0.9 0.1 UrbanlBuilt-Up 256 0.8 0.1 Urban Grassland 47 0.1 0.0 Wetland 1,693 5.2 0.3 Forested 1,186 3.6 0.2 Nonforested 507 1.6 0.1 Other Land 732 2.2 0.1 Lakes and Streams 718 2.2 0.1 Barren and Exposed 14 0.0 0.0 Total 32,796 100.0 6.3

Pecatonica Creek (lower middle) Subbasin Category Acres % Subbasin % Area Agricultural Land 27,931 81.2 5.5 Cropland 17,101 49.7 3.4 Rural Grassland 10,829 31.5 2.1 Forest and Woodland 1,875 5.4 0.4 Urban and Built-Up Land 714 2.1 0.1 UrbanlBuilt-Up 436 1.3 0.1 Urban Grassland 278 0.8 0.0 Wetland 3,103 9.0 0.6 Forested 1,925 5.6 0.4 Nonforested 1,178 3.4 0.2 Other Land 763 2.2 0.2 Lakes and Streams 754 2.2 0.2 Barren and Exposed 10 0.0 0.0 Total 34,386 100.0 6.8

88 Pecatonica River (lower) Subbasin Category Acres % Subbasin % Area Agricultural Land 18,120 83.0 3.6 Cropland 11,537 52.8 2.3 Rural Grassland 6,583 30.2 1.3 Forest and Woodland 1,221 5.6 0.2 Urban and Built-Up Land 438 2.0 0.1 UrbanIBuilt-Up 217 1.0 0.0 Urban Grassland 221 1.0 0.0 Wetland 1,649 7.6 0.3 Forested 1,172 5.4 0.2 Nonforested 477 2.2 0.1 Other Land 409 1.9 0.1 Lakes and Streams 409 1.9 0.1 Barren and Exposed I 0.0 0.0 Total 21,836 100.0 4.3

89