{
 "description": "\nThis 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.)\n\nCahokia Alluvium\nParkland Sand\nEquality Formation, Dolton Member\nHenry Formation\nSand and gravel within Wedron Formation\nSand and gravel within Winnebago Formation\nPearl Formation (includes Hagarstown Member)\nSand and gravel within Glasford Formation\nMounds gravel and related units\nCretaceous sediments, silts, sands, etc.\nPennsylvanian rocks, mainly sandstones\nMississippian rocks, mainly limestones, some sandstones\nSilurian and some Devonian rocks, mainly dolomite\nOrdovician and Cambrian rocks, mainly dolomite, some sandstone\n\nThe scale of these data is 1:250,000.\n",
 "summary": "summary",
 "tags": [
  "NATCARB",
  "atlas",
  "atlas v",
  "ccs",
  "co2",
  "carbon storage",
  "coal",
  "gas",
  "oil",
  "saline",
  "sequestration",
  "sources"
 ],
 "accessinformation": "",
 "MinScale": 250000.0,
 "MaxScale": 0.0,
 "Snippet": "summary",
 "title": "Illinois_Shallow_Coarse_Material_Aquifer",
 "thumbnail": ".bmp"
}