STRATIGRAPHICAL GEOLOGY. 50 1 



B. Middle Jurassic. 



(b] Corallian group. 



13. Astarte Limestone. 

 12. Nerinea Limestone, 

 ii. Coral Oolite. 

 10. Coral Limestone. 

 (a) Oxford group. 



9. Terrain a chailles. 



8. Oxford Clay and Kellaways Rock. 



A. Lower Jurassic or Oolite Group. 



7. Dalle nacree ( = Cornbrash ?). 



6. Calcaire roux sableux ( = Forest Marble?) 



with Ostrea Knorri. 



5. Great Oolite (Plagiostoma elongata, etc.). 

 4. Marls with Ostrea acuminata ( = Fullers' 



Earth?). 



3. Compact Oolite. 

 2. Ferruginous Oolite, 

 i. Gres superliasique (marly Sandstone). 



Terrain Liasique. The works of Merian, Thirria, and 

 Thurmann were supplemented by Count von Mandelslohe's 

 memoir entitled Sur la Constitution g'eologique de FAlbe du 

 Wurtemberg (1836). Mandelslohe contributed several good 

 geological sections, and drew a careful comparison between 

 the palaeontological sequence of the deposits in the Swabian 

 Jura and that exhibited in the Jurassic deposits of England, 

 Switzerland, and France. 



Dufrenoy and Elie de Beaumont commenced their in- 

 vestigations on the French Jurassic deposits in 1825. The 

 more important results were communicated in several 

 memoirs, which were then published collectively in four 

 volumes in the year 1838. Ten years later a comprehensive 

 account of the " Terrain du calcaire Jurassique " was given 

 by the same two authors in elucidation of the geological map 

 of France. This was for several decades the standard 

 work on the Jurassic deposits of France. Dufrenoy and 

 De Beaumont defined and sub-divided the "Terrain 

 Jurassique" of France precisely after the model of the English 

 authors. They succeeded in demonstrating the parallelism of 

 all the main sub-divisions in the French and English 

 developments of the series, and introduced into French 



