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|Title:||Hydrogeology of glacial deposits of the Mahomet Bedrock Valley in east-central Illinois|
|Author(s):||Stephenson, David A.|
|Abstract:||The Mahomet Bedrock Valley localizes highly permeable sand and gravel aquifers that are the only developed source of large ground-water supplies in east-central Illinois. These aquifers were studied by quantitative methods of geologic evaluation, and their three-dimensional configurations were determined. Three hydrostratigraphic units are recognized within the drift. These units correlate with deposits of the Wisconsinan, Illinoian, and pre-Illinoian Stages of the Pleistocene Epoch . Pre-Illinoian sand and gravel strata occur within the drift filling the deepest portions of bedrock channels and constitute aquifers with a potential for increased groundwater development. These deposits are permeable, may exceed 150 feet in thickness, and appeartobe present throughout a large percentage of the bedrock channels . Illinoian deposits contain a smaller proportion of permeable strata than pre -Illinoian deposits, but are presently the most widely utilized for small and moderate ground-water supplies. Wisconsinan deposits do not contain extensive permeable strata except for local occurrence of sand and gravel in depressions on the buried Sangamonian land surface. Lithofacies maps were prepared for each 100-foot elevation interval to determine the three-dimensional distribution of aquifers within the drift. These maps illustrate one method of defining aquifer distribution in an economic and expedient manner and they afford the basis for extrapolating limited hydrologic data. Coefficients of transmissibility are estimated from specific-capacity data and are related to geologic units.|
|Publisher:||Urbana, IL : Illinois State Geological Survey|
|Series/Report:||Circular no. 409|
Bibliography: p. 43-44.
|Rights Information:||Public domain. Illinois state government document.
Copyright 1967 Board of Trustees University of Illinois.
|Date Available in IDEALS:||2012-11-08|
|Identifier in Online Catalog:||6167804|