FEATURES OF FORT DODGE GYPSUM 



591 



The other locality where this conglomerate was found is at the 

 pit of the Vincent Clay Products Company at Shady Oaks sta- 

 tion on the Fort Dodg'e, Des INIoines and Souttiern Railway. This 

 is at the mouth of Two jNIile creek on the east bank of Des 

 Moines river directly opposite the ravine in wh'ch the previously 

 described outcrops occur. Here the conglomerate is absent from 

 some places while at others it is a foot or a foot and a half thick. 

 It Is red and gray and most of the pebbles are less than one-half 

 inch in diameter. Parts of the conglomerate rre really a coarse 



Fig. 19S — The irregular surface of tlie gypsum buried in drift, Vincent 

 clay pit, Port Dodge. 



sandstone. Fossils were found in streaks and pockets of the 

 coarser materials. 



A noteworthy feature in this pit as well as ni several others is 

 the fact that the upper few feet of the Coal Measures shales just 

 under the gypsum is highly colored, red, blues, purples and light 

 grays predominating. These lighter colors grade into black be- 

 low. Whether this lighter coloration is inherent in the shales or 

 is due to the chenncal action of the dissolved gypsum as it per- 

 colates downward is not clear. 



