GEOLOGY OF SOUTHWESTERN IOWA. 349 



Geology. The Upper coal-measure strata alone have been 

 found exposed in this county, but it is probable that some 

 outliers of the Mshnabotany sandstone exist beneath the 

 surface in the northwestern part. The strata thus far dis- 

 covered are all referred to the horizon of the lower half of 

 the series of limestones and shales of the Winterset section. 

 At Hawleysville, just upon the east border of the county, 

 there is an exposure of about five feet in thickness of bluish, 

 argillaceous limestone, with partings of blue, clayey shale. 

 These are no doubt the equivalents of a part of the strata 

 associated with the coal bed at Foster's in the northwestern 

 part of Taylor county, but no coal has yet been discovered in 

 connection with the strata at Hawleysville. Crossing over to 

 the valley of the West Nodaway, the next exposure of strata 

 found were upon the left bank of the stream a little below 

 Clarinda, the county seat. Here the same bed of coal is 

 found again which is worked at various points in Taylor 

 and Adams counties together with their associated strata. 

 The coal is here of about the same thickness (from fifteen to 

 twenty inches) as in the last named counties, and its 

 associated strata have the same general characters. It has 

 been mined just below the mill near Clarinda, and also at 

 several points within a mile below fig. 30. 



the mill on the east side of the 

 river. The following section, illus- 

 trated by Fig. 30, was measured 

 there, commencing with the surface 

 of the river as the base of No. 1. 



to' 



Section near Clarinda. 



No. 5. Hard, bluish, impure limestone 2 feet. 



No. 4. Bluish, clayey shale ±i£ f ee t. 



No. 3. Coal 134 feet. 



No. 2. Light, bluish, clayey shale, containing fossil plants and 



shells 2 feet. 



No. 1. Unexposed to the water's edge 10 feet. 



Total , 16% feet. 



