370 SPECIAL GEOLOGY. 



fa. Upper freshwater limestone marls, and siliceous 

 , j T T, millstone. 



' 1 b. Upper marine sands, or Fontainbleau sand- 

 [_ stone, and sand. 

 (a. Lower freshwater limestone and marl, or 



gypseous series. 

 I b. Sandstone and sands, with marine shells (Sables 



2. MIDDLE EOCENE . -{ moyens). 



I c. Calcaire yrossicr, limestone, with marine shells, 

 I d. Cakaire siliceux, hard freshwater formation,. 

 ^ contemporary with c. 



fa. Lower sands, with marine shelly beds (lits 



3. LOWER EOCENE . 1 ^ L ^" ^^ ^.^ j.^ and pkstic cky 



(argiles plastiqiie). 



It is assumed that an ancient gulf or depression of the 

 chalk -was filled by a sea of later date, which, extending on 

 the north to the main ocean, was bounded on the south by 

 a tract of land, the rivers of which brought down and depo- 

 sited in its waters the spoils of the country over which they 

 flowed, the remains of animals and plants, and the shells of 

 the river and the land, while mineral waters were occa- 

 sionally mingled with those of the sea. Changes took place 

 in the relative level of land and water, producing fresh 

 accumulations on the older deposits, and, after extensive 

 vicissitudes of this nature requiring a long period of time 

 for their development, the country rose to its present eleva- 

 tion. 



ORGANIC REMAINS. The gypsum quarries of Montmartre 

 had long been known to afford fossil remains. Collections 

 of these objects had been formed, and Guettard had figured 

 and described many of the bones and teeth. But it was 

 reserved for the illustrious Cuvier to complete the inves- 

 tigations thus commenced, and to effect discoveries whicli 

 have given a new impetus to scientific research. By following 

 the principles which he had previously applied with success 

 to the investigation of fossil elephants, he undertook the 

 task of restoring these osseous fragments to their true 

 place in the zoological series. His intimate knowledge of 

 the laws of structure enabled him to refer each bone, or 

 portion of a bone, to its approximate position in the oste- 

 ology of the -animal, till their novel forms, as it were, lived 



