[Reports volI-XIII] . een divided into three lime-stones. Of these the Ste. Genevieve has never come into gen-eral usage, and practically has been forgotten. The SaintLouis limestone proper has been widely recognized, and inmany places the lower portions have been correlated with theWarsaw beds as developed at the mouth of the Des Moinesriver. The Augusta group is now made to include all five of thehitherto recognized beds—the Warsaw proper, the geode SUBDIVISIONS OP GOAL MEASURES. 79 layer, the Keokuk and the upper and lower Burlington lime-stones. The Kinderhook group is a three-fold divisio
[Reports volI-XIII] . een divided into three lime-stones. Of these the Ste. Genevieve has never come into gen-eral usage, and practically has been forgotten. The SaintLouis limestone proper has been widely recognized, and inmany places the lower portions have been correlated with theWarsaw beds as developed at the mouth of the Des Moinesriver. The Augusta group is now made to include all five of thehitherto recognized beds—the Warsaw proper, the geode SUBDIVISIONS OP GOAL MEASURES. 79 layer, the Keokuk and the upper and lower Burlington lime-stones. The Kinderhook group is a three-fold division whose sev-eral members are strongly contrasted and persistent over wideareas. Upper Carboniferous Series or Coal Goal Measures of the upper Mississippi region rest inmarked unconformity upon the strata beneath. Within mostof the district the rocks immediately below are portions of theLower Carboniferous, but sometimes older formations come in,Devonian or even Silurian. The surface upon which the coal-. Fig. 8. Coal Measure Sandstone Eesting on Saint Lonis Limestone. Keoknk. bearing strata is laid down is everywhere uneven, the irregu-larities being of such a nature as to leave but little doubt thatit is an old land surface. The character of this old erosionplane is shown in the accompanying fisrure (8), and also inplate ix. Over the greater part of the Carboniferous area of theMississippi basin, the Coal Measures are capable of being sepa-rated into two portions—one, which forms a marginal zone andis commonly called the lower division, and the other, depositedin more open water, termed the upper section. The two for-mations are usually tolerably well contrasted in a general way, 80 GEOLOGICAL FORMATIONS. though the exact line of separation, is not always clearly dis-tinguishable. In Missouri, however, it has been customary to regard theCoal Measures as made up of three distinct members: Lower,Middle and Upper. These three divisions, though repeatedlydescribed
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