. Underground water resources of Iowa . rom the Kansan in weU drilling,unless it should be separated from it by ill-smelling soils, by peatand forest beds, or by the more welcome water-bearing sands andgravels which not infrequently mark tliis horizon. The Nebraskantill rests either on bedrock or on thin sand and gravels which separateit from the rock. The rocks of Keokuk County belong to two great series of theCarboniferous system, the Pennsylvanian and the Mississippian.(See PI. XIV.) The Pennsylvanian is exposed to view or is foundby the drill immediately below the drift over large areas in
. Underground water resources of Iowa . rom the Kansan in weU drilling,unless it should be separated from it by ill-smelling soils, by peatand forest beds, or by the more welcome water-bearing sands andgravels which not infrequently mark tliis horizon. The Nebraskantill rests either on bedrock or on thin sand and gravels which separateit from the rock. The rocks of Keokuk County belong to two great series of theCarboniferous system, the Pennsylvanian and the Mississippian.(See PI. XIV.) The Pennsylvanian is exposed to view or is foundby the drill immediately below the drift over large areas in thewestern townships and in several scattered outliers over the remain-der of the county. The rocks of the Pennsylvanian series consist ofshale (soapstone or slate), with seams of coal and beds of fire Feet90O- 8nu- 700- fiOO- 600 400- 300- 200- U, S. GEOLOGICAL SURVEY Pella ^ V^®^^ DesMo ? St Lou»s V\m« 100 Sea level 400-500-fiOO U, S, GEOLOGICAL SURVEY - 37 miles 27 miles W^TER-SUPPLY PAPER 293 PLATE XIV ->. GEOLOGIC SECTION BETWEEN FELLA AND LETTS, IOWABy W H. Norton KEOKUK COUNTY. 549 clay, and lenticular bodies of sandstone. These rocks lie on a deeplyeroded surface of Mississippian strata. The outcrops of the Mississippian series in this county present onlyits higher subdivisions. The St. Louis limestone, with its variablebeds of limestone (some fine grained and compact, some magnesian,some sandy, some interbedded with sandstone layers, and some madeup of angular fragments) and of sandstone which in places may attaina thickness of 40 feet, underlies the greater portion of the area. Thetotal thickness of the St. Louis may reach 150 feet. The Osage group underlies the St. Louis limestone. Its expo-sures in the county show a subcrystalline limestone locally made upof crinoidal fragments in many places pure white. It occurs in layerscommonly less than a foot thick, separated by bands of chert or ofclay. The Osage underlies the drift northeast of a line drawndiagonally
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Keywords: ., bookcentury1900, bookdecade, booksubjectwatersupply, bookyear1912
