ancient Gj/psum of the Alps. 65 



series ; and they all agreed in admitting the gypsum of St. 

 Gothard to be primitive ; celebrated geologists had visited it, 

 and had considered it as such. M. Daubuisson had observed 

 the gypsum of the valley of Aosta, which he considered 

 also as primitive ; so that in all mineralogical and geolo- 

 gical works, a gypsum formation was seen placed in the 

 class of primitive rocks. 



It was not altogether absurd to admit among the gypsum 

 of the Alps, primitive and transition gypsum, and at the 

 same time another gypsum, very ancient, but of later for- 

 mation ; the two first divisions have indeed been generally 

 admitted. But I had seen specimens of all these gypsums, 

 and, on comparing them together, I found so much resem- 

 blance, so many relations, and, if I may so express myself, 

 such a striking family air, that I could not determine to 

 allow them different origins ; on the other hand, it was im- 

 possible for me to agree with the idea of primitive forma- 

 tion, which was attributed to many of them, from the geolo- 

 gical characters afforded me by that of Tarentaise. I had 

 briefly exposed all these doubts in the memoir on the transi- 

 tion series ; I have since further developed them in a note 

 read before the Societe Philomathique, which has not b€eii 

 printed : I shall now occupy myself with their solution. It 

 will be seen that my new researches have led me to conjec- 

 tures differing a little from my first, but at the same time I 

 conceived myself obliged not to admit the primitive gypsums 

 against the opinion now adopted by all geologists, even 

 those most celebrated. 



I had already, in 1809, visited the gypsum of the valley 

 of Cogne, announced as primitive by M. Daubuisson ; I had 

 the advantage of having him as a guide in this excursion ; 

 but I was thwarted by the great abundance of snow that had 

 fallen in the preceding winter, the melting of which had 

 been much retarded. The gypsum was covered by it, and 

 I could only observe the surrounding rocks. 



In 1813, the order I received to conduct the students of 

 the mines in a geological tour in the Alps, appeared a fa- 

 vourable opportunity to me ; being entirely master of my 



