C. A. White on the Geology of Southwestern Iowa. 81 
3. The lower Coal-measures alone are —_ along the Des- 
Moines river, and to the northward and eastw 
. The upper Coal-measures lie wholly to a southward and 
measures 7 the eastern border. 
A ds of the upper series thin out, but no true un- 
cuiifosiinhilinasd is recogni 
8. The upper series is believed to contain but one bed of coal, 
properly speaking, the maximum thickness of which is twenty 
inches, and its greatest development along the Nodaway river. 
The stratigraphy of the whole region is very simple, the 
line of strike being practically east and west, and the dip, to 
the southward nearly coincident with the fall of the streams. — 
10. The highest Paleozoic beds are to be found in Madison 
county and belong to the upper Coal-measures. 
11. The lowest beds exposed along the Missouri river, or upon 
its water-shed within the region herein described, belong also to 
the upper Coal-measures as designated on the previous pages. 
12. No Subcarboniferous rocks are found westward from the 
immediate vicinity of the DesMoines river. 
18. There is a definite carbo-argillaceous horizon recognized 
over the greater part of this region which is characterized b 
the bed of coal before referred to, and in the strata of whic 
racine e gereaeh and gasteropods ‘prevail, and sometimes ee 
om 
14. Above = horizon as well as below it, —— upper 
Coal-measure brachiopods, and other fossils prevail 
15. —— thie horizon the rocks increase in thickness and 
calcareous character from east to west, and probably also to the 
southw: ened: 
16. Nishnabotany sandstone occurs in the —— of Mills, 
Montgomery, Cass and Pottowatamie. It lies unconfo: 
upon the upper Coal-measure rocks, and is supposed to > be of 
Cretaceous age. 
Towa City, Iowa, March 27th, 1867. 
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