ON THE STRATIGRAPHY OF THE PLATTE 



SERIES, OR UPPER CRETACEOUS OF 



THE PLAINS. 



BY F. W. CRAGIN. 



THE PLATTE SERIES. 



The rocks of the North American Interior Cretaceous 

 belong to two great series. The lower of these, consisting 

 chiefly of limestones, with subordinate terranes of shale, 

 marl, and sandstone, and having its fullest development in 

 Texas and Mexico, has been named the Comanche series. 

 The upper series, into which shales and sandstones more 

 largely enter, but which has important limestone formations 

 also, may most appropriately be called the Platte series, after 

 the Platte river, which, in Colorado and Nebraska, cuts all 

 of the divisions of the series and all of the formations recog- 

 nized as belonging to it in the typical area of its occurrence, 

 viz., that segment of the North American Interior plateau 

 which extends from the Rocky Mountains eastward, and 

 constitutes the higher portion of the Plains. 



The Platte series includes the following divisions: 



Dakota, Benton, Niobrara, Fort Pierre, Fox Hills, and 



Laramie. 



Following are brief preliminar}' notices of some of the 



formations that compose that portion of the Platte series 



which is included within the limits of Kansas. 



THE RUSSELL FORMATION. 



The lower formation of the Benton in Kansas. Named 

 from Russell, Kansas, around which it outcrops in ravines. 



