Observations on the formations of Ancient* 

 Gypsum occurring in the Alps, particularly 

 on those considered as primitive; preceded hy 

 new facts relative to the transition rocks of that 

 chain. By M. Brochant de Villiers, 

 Engineer in Chief of the Royal Mining Corps; 



(Annales des Mines for 1817)i 

 Read at the Royal Academy of Sciences, March 11, 1816. 



[^THE author commences this memoir by observing, that 

 geology had made rapid advances since Werner had first 

 called the attention of geologists to the different rock forma- 

 tions ; that nevertheless the formations originally traced by 

 Werner, had been subsequently modified by himself, his 

 pupils, and others ; that the study of shells, and of fossil 

 organized bodies in general, had tended greatly to advance 

 our knowledge of secondary rocks ; that less attention had 

 of late been paid to the primitive rocks ; but that the tran- 

 sition series had been the object of numerous researches. 

 He mentions Messrs. Von Buch, Haussman, Brongniart, 

 Omalius, Raumer, and Bonnard, as the principal naturalists 

 who have thrown light on this class. 



M. Brochant de Villiers states at the same time, that be- 

 fore their observations were known, he had also applied 

 himself to this branch of enquiry, and that in a memoir 



* The author appears to use the words " Ancient gypsum," in con- 

 tradistinction to the Tertiary gypsum. (Trans). 



