GEOLOGY OF SOUTHWESTERN IOWA. 



351 



No. 6. Layer of compact limestone. 



foot. 



No. 5. Dark colored, carbonaceous shale, passing upward into 



light blue, clayey shale 2^ feet. 



No. 4. Layer of compact, bluish, impure limestone. , i^ foot- 

 No. 3 Bluish, carbonaceous t-hale, with thin, calcareous seams. . . 4 feet. 



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



No. 1. Bluish, concretionary and shaly limestone 1 1^ fjet. 



Total 17 feet. 



These beds are all thought to belong beneath the horizon 

 of the coal bed farther up the valley, and seem to have been 

 elevated here by a very slight fold or undulation in the strata. 



Going still further down the valley of the Nodaway, and 

 about two miles within the borders of the State of Missouri, 

 another exposure of strata is found Fig. 33. 



in the banks of the stream in which /-- ) 



the same bed of coal is recognized 



that had been so often seen farther 



up the valleys of the same stream 



and its branches. The following 



section and Fig. 23, represent the ijs^m ^ m^ ^^^ ^^ 



strata exposed there. 



Section two miles bdow Brady's Mill. 



Yellowish, marly shale 14 



Shaly, impure limestone 4 



Carbonaceous shale 1 



Coal 1 5 



No. 5. 

 INo. 4. 

 No. 3. 

 No. 2. 

 INo. 1. Light bluish shale with remains of plants 



feet, 

 feet, 

 foot, 

 foot, 

 feet. 



Total 21f £ feet. 



Going westward from the 

 valley of the Nodaway, we 

 find the next exposures of 

 strata in the valley of the 

 main Tarkeo. These are 

 slightly exposed at intervals 

 from the northern to the 

 southern boundary of the 

 county. The following sec- 

 tion, illustrated by Fig 34, 



Fig. 34. 



