Circular - Division of the Illinois State Geological SurveyIllinois State Geological Survey., 1938 - Mines and mineral resources |
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Common terms and phrases
anhydrite Arch argillaceous basal base basement beds belt brittle brownish gray calcitic Cambrian and Lower Cambrian rocks carbonate chert clastic coarse CROIXAN cubic miles dark brown deep Derby-Doerun Devonian dolo dolomite drilled drusy quartz Dutchtown Eau Claire Everton feet thick figure formations Franconia Galena geophysical glauconitic grains Grand Detour gray to light green Gunter Illinois Basin Indiana Joachim Kentucky KNOX MEGAGROUP LaSalle light brown light gray light grayish brown Limestone Megagroup lithographic lithologic Lower Ordovician Maquoketa medium micaceous Middle Ordovician Mississippian Missouri Nachusa northern Illinois occur Ohio Oneota oolitic oolitic chert Ordovician and Cambrian Ottawa Ottawa Megagroup Pennsylvanian percent Peter Sandstone pink Platteville Potosi Precambrian quartz Red granite region resistivity Rhyolite Rough Creek Zone sand sandy sediments self-potential Shakopee Shakopee Dolomite shale shaly siltstone silty Simon slightly glauconitic south-central southern southward strata stratigraphic structural sub-Tippecanoe unconformity thickens thin unconformity units upper