"68 On the Submergence of Continents. 



after a certain lapse of time, there vvould necessarily be formed 

 a series of strata analogous to those which occur in the upper 

 part of the same deposits of various countries. 



Proceeding from these data, and supposing, in general, that 

 the level of the sea has actually imdergone a slow and progres- 

 sive lowering from the origin of things, the author undertakes 

 to explain the manner in which the tertiary deposits of the 

 neighbourhood of Paris have been formed, as well as those 

 which constitute their continuation, whether extending to the 

 Loire, or across the Channel in the neighbourhood of the Isle of 

 Wight. Considering all these deposits as belonging to an an- 

 cient basiuj he represents their constitution by means of two 

 transverse sections, in which he has brought together all the ob- 

 servations that have hitherto been collected, and which afford a 

 precise idea of the alternations, mixtures, and entanglements 

 which the various deposits present. The author is of opinion that 

 these sections are sufficient, with the aid of the explanations an- 

 nexed, to shew that marine strata of chalk, coarse limestone, 

 marls, and superior sandstones, have been formed in the same 

 basin, and under the same waters, as the plastic clay, the sili- 

 ceous limestone, and the gypsum itself, which essentially con- 

 tain remains of terrestrial and fluviatile animals and vegetables ; 

 but he does not fail to add to his system of explanation, all the 

 details and inductions which appear to him calculated to insure 

 probability. The following is a brief statement of his views. 



First Epoch. — A calm and deep sea deposits the two varie- 

 ties of chalk which constitute the sides and bottom of the great 

 tertiary basin in question. 



Second Epoch. — In consequence of the progressive lowering 

 of the ocean, the great basin becomes a gulf, in which matters 

 carried down by the rivers form chalky brecciae and plastic clay, 

 are soon covered by the marine spoils of the first coarse lime- 

 stone. 



Third Epoch. — The deposits are interrupted by a commo- 

 tion which breaks and sensibly displaces the strata. The basin 

 becomes a salt lake, traversed by voluminous currents of water 

 coming alternately from the sea and the continents, and which 

 produce the mixtures and entanglements presented by the se- 



