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This map shows the distribution of coarse-grained materials and permeable bedrock within 50 feet of ground surface in Illinois. This includes bedrock, sand and gravel, and alluvial units with characteristics that suggest a potential to store or conduct groundwater and yield potable water to wells and springs. It was derived from stack-unit map data. Aquifers or potential aquifers on this map are defined as sand and gravel units at least five feet thick, sandstone at least ten feet thick, and fractured limestone or dolomite at least fifteen feet thick with a lateral extent of at least one square mile. Minor aquifers typically yield from five to seventy gallons of potable water per minute. Potable water is defined as water containing less than 2,500 mg/L of total dissolved solids. For use in this data set, the following stratigraphic units are considered to be aquifers or potential aquifers meeting these criteria: (although Cahokia Alluvium is primarily fine-grained, it is included because it contains numerous sand and gravel deposits.)
Cahokia Alluvium
Parkland Sand
Equality Formation, Dolton Member
Henry Formation
Sand and gravel within Wedron Formation
Sand and gravel within Winnebago Formation
Pearl Formation (includes Hagarstown Member)
Sand and gravel within Glasford Formation
Mounds gravel and related units
Cretaceous sediments, silts, sands, etc.
Pennsylvanian rocks, mainly sandstones
Mississippian rocks, mainly limestones, some sandstones
Silurian and some Devonian rocks, mainly dolomite
Ordovician and Cambrian rocks, mainly dolomite, some sandstone
The scale of these data is 1:250,000.
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["NATCARB","atlas","atlas v","ccs","co2","carbon storage","coal","gas","oil","saline","sequestration","sources"] |