342 SYDNEY H. BALL 



regions the exposures are fewer, possess a trail-like form, and are 

 largely confined to valleys. From the latter conditions we infer 

 that in the vicinity of the river, erosion has removed all but the 

 Graydon sandstone deposited in deep gulches. These again seem 

 "resurrected" valleys. The inclosing Cambro-Silurian walls are 

 undisturbed, and seem to delimit normal erosion valleys. 



The Graydon sandstone appears to have been deposited upon a 

 surface somewhat like the present, with the greatest dissection in 

 the vicinity of the Osage River. If important valleys of Graydon 

 age had existed in the upland, we should find in this little dissected 





Fig. 3- — Cross-section — Son Prospect. Dotted line shows hypothetical extent of 

 Coal-Measure shale. 



portion of the uplift sandstone outcrops corresponding to them. If 

 in the vicinity of the Osage the streams had run counter to the pres- 

 ent channels, we would expect the resistant Cambro-Silurian rocks 

 to preserve more filled channels crossing the present divides. 



Cross-bedding and pebbles occur throughout the sandstone, and 

 so deposition apparently kept pace with gradual depression. The 

 first beds were perhaps deposited in estuaries, while later the whole 

 land may have been submerged. From the probable geography of 

 the time it may be suggested that the sand came from the south or 

 southeast. From its lack of felspathic material, it was doubtless 

 derived from the older Cambro-Silurian sandstones, and not from 

 the granites of southeast Missouri. 



After the deposition of the Graydon sandstone the land was again 

 uplifted. 



