Geologic Mapping in Northeastern Illinois&&

What do we know about Lake County’s Geology?Lake County s Geology?

Donald A. Keefer, DirectorGeologic Mapping and Hydrogeology Center

Societal Benefits of MappingSocietal Benefits of Mapping• Water Supply Delineation, Protection and Managementpp y g• Aggregate Resource Delineation, Protection and

Management• Construction Engineering Guidance• Mineral Resource Delineation, Planning and

ManagementManagement• Development of Energy Infrastructure• Habitat and Wildlife ProtectionHabitat and Wildlife Protection

Mapping has an excellent cost to benefit ratio

ISGS Geologic Mapping in N h Illi iNortheastern Illinois

• Central Great Lakes Geologic Mapping Coalition (a.k.a. “The C li i ”) hi h l i 3 D i h h L k CCoalition”): high resolution 3-D mapping throughout Lake County; Federal and State funding

• STATEMAP Program: Lake, Cook, Kane, McHenry Counties; high l ti i f fi i l t i l F d l d St t f diresolution mapping of surficial materials; Federal and State funding

• Northeastern Illinois Water Supply Planning Region: regional geologic mapping for Fox River Basin sand and gravel aquifers and surficial bedrock aquifer regional characterization of deep bedrocksurficial bedrock aquifer, regional characterization of deep bedrock aquifer and confining unit; State funding

• Kane County: high to medium resolution 3-D mapping; County and State fundingState funding

• Kendall County: medium resolution 3-D mapping; County and State funding

Costs Vary with GeologyCosts Vary with Geology

• Costs are dependent on geologicCosts are dependent on geologic complexity

• Northeastern Illinois collar counties• Northeastern Illinois collar counties demonstrate range of issuesS b f l it ft diffi lt t• Subsurface complexity often difficult to estimate without new data

Water Supply Planning Regions

Water Supply Planning and ManagementManagement

State Geological Survey role:M i d h t i i• Mapping and characterizing– Deep Bedrock Aquifer– Confining units of Deep Bedrock Aquifer– Confining units of Deep Bedrock Aquifer– Glacial aquifers and surficial bedrock aquifer,

particularly within Fox River Basin– Glacial aquifers within and above Mahomet bedrock

valley (Mahomet aquifer system)• Create and improve 3-D geologic maps andCreate and improve 3 D geologic maps and

work with SWS colleagues to help integrate these into groundwater flow models

Water Supply Planning and MManagement

• Exploring new methods for bedrockExploring new methods for bedrock aquifer characterization

• Characterizing confining units• Characterizing confining units• Evolving 3-D geologic mapping approach

t i t t i ti f l i lto integrate existing maps of glacial deposits for large Fox River Watershed

Outwash sand & gravel units

Geologic MappingIn Kendall CountyIn Kendall County

Geology of Lake CountyGeology of Lake County

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ZIONANTIOCHFOX LAKE WADSWORTH

WAUKEGANWAUCONDA GRAYSLAKE LIBERTYVILLE

LegendLithostratigraphic units

Cahokia Formation (alluvium)

Disturbed Ground

Equality Formation (lake sediment

Grayslake Peat (organic)

Henry Formation (outwash)

Wadsworth Member (diamicton)

Haeger Member (diamicton)

Water

WHEELING HIGHLAND PARKBARRINGTON LAKE ZURICH

ZIONANTIOCHFOX LAKE WADSWORTH ZIONANTIOCHFOX LAKE WADSWORTH

WAUKEGANWAUCONDA GRAYSLAKE LIBERTYVILLE

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Cahokia Formation (alluvium)

Disturbed Ground

Equality Formation (lake sediment

Grayslake Peat (organic)

Henry Formation (outwash)

Wadsworth Member (diamicton)

WHEELING HIGHLAND PARKBARRINGTON LAKE ZURICH

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3D Geologic Mapping in Lake County, IL

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3D Geologic Mapping in Lake County, IL

ZIONANTIOCHFOX LAKE WADSWORTH

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LegendLithostratigraphic units

Cahokia Formation (alluvium)

Disturbed Ground

Equality Formation (lake sediment

Grayslake Peat (organic)

Henry Formation (outwash)

Wadsworth Member (diamicton)

Haeger Member (diamicton)

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Aquifers of Northeastern Illinois

ChiDeKalb

West East

ChicagoDeKalb

Unconsolidated Aquifer System

Shallow Bedrock Aquifer

Deep Bedrock Aquifer SystemDeep Bedrock Aquifer System

Elmhurst-Mt. Simon AquiferCross-Section Modified from Bretz (1939)

Sand and gravel pit on the Fox RiverSand and gravel pit on the Fox River

Fractured DolomiteFractured Dolomite

<2,500 mg/L TDS

2,500-10,000 mg/L TDS

>10,000 mg/L TDS

Geologic Mapping in Northeastern Illinois&&

What do we know about Lake County’s Geology?Lake County s Geology?

Donald A. Keefer, DirectorGeologic Mapping and Hydrogeology Center