26o 



HISTORICAL PALEONTOLOGY. 



Generalised Section of the Cretaceous Series 

 OF Britain. 



Fig. 185. 



W J 



3 1 



U 



Eocene. 

 -White Chalk with Flints. 



-White Chalk without Flints. 



■Chalk Mad. 

 -Upper Greensand. 



-Gault. 



Lower Greensand or Neo- 



Weald Clay. 



^ Wealden Series. 



—Hastings Sands. 



In North America, strata of Lower Cretaceous age are well 

 represented in Missouri, Wyoming, Utah, and in some other 

 areas-; but the greater portion of the American deposits of 

 this period are referable to the Upper Cretaceous. The rocks 

 of this series are mostly sands, clays, and limestones — Chalk 

 itself being unknown except in Western Arkansas. Amongst 

 the sandy accumulations, one of the most important is the so- 



