i86 



Upper Oolites. 



Ammonites, a few Gasteropoda, and various genera of 

 bivalves, common in the Oolitic formations. 



This formation is rarely more than about 300 feet 

 thick, and about one-third of its fossils are well known 

 in older Oolitic strata, while less than a tenth pass 

 FIG. 38. 



Ammonites Jason. Cidaris florigemma. 



G-ryphsea clilatata. 



Belemnites hastatus. 



Isastrasa explanata. Chemnitzia Heddingtonensis. Pholadomya aequalis. 

 Group of Fossils in the Middle Oolites. 



upward into the overlying Kimeridge Clay and Port- 

 land rocks. 



For reasons connected with the physical geography 

 of this epoch, which will be mentioned further on, I 

 confine the Upper Oolite to two formations, viz. : 



Portland Limestone and Sand, 

 Kimeridge Clay. 



The stratigraphical arrangement of these strata and 



