380 COUNTY AND KEGIONAL GEOLOGY. 



that border the great flood-plain of the Missouri, and near 

 the railroad track a short distance below the town of 

 Crescent. The following named strata are found there: 



Section near Crescent. 



No. 3. Light, brownish gray limestone 1 foot. 



No. 2. Light gray oolitic limestone 2^ feet. 



No. 1. Impure concretionary limestone 1 foot. 



Total 4^ feet, 



Near the place were these strata are exposed, a shaft was 

 sunk about twenty feet in depth, which passed through much 

 yellowish, marly shale and occasional layers of impure 

 limestone. Near the bottom, a layer of black laminated 

 carbonaceous shale was found, which has the same general 

 character as that so often found among the strata of all the 

 coal-measures. These exposures of strata hitherto mentioned 

 are the only ones that have been observed within the limits of 

 this great county. 



Material Resources. Almost every acre of the surface of 

 Pottawattamie county is not only very fertile, but tillable; 

 and when it is remembered that it contains more than half a 

 million of acres of tillable land, some idea may be obtained 

 of the magnitude of the resources that may be annually drawn 

 from its soil. Its other resources, at present available, 

 consist of its stone and forest trees. Its stone, as will appear 

 from the foregoing paragraphs upon its geology, is not abun- 

 dant; but good lime has been prepared from the limestone at 

 Stutsman's mill, on Mosquito creek, and near Crescent; and 

 the stone at all these places is also suitable for ordinary 

 building purposes, and some of it for dressing. The Mshna- 

 botany sandstone, before mentioned as being exposed in the 

 East Mshnabotany, is there much too soft for any economic 

 purpose. 



Along the base of the bluffs, between Crescent and Council 

 Bluffs and elsewhere, the altered drift, consisting of more 

 or less distinctly stratified sand and gravel, has become 



