QQ M. BnocHANT on the 



route, I directed it principally to many points, where I 

 knew gypsum existed, and more particularly to those that 

 had been noticed as primitive. 



From Moutiers in Savoy, where the practical mining 

 school then was, I passed the central chain of the Alps by 

 the Col de la Seigne, and the AUee Blanche. I descended 

 into the valley of Aosta, from whence I visited that of 

 Cogne ; afterwards crossing the mountains which form as it 

 were the advanced posts of the Alps on the side of Pied- 

 mont, I reached St. Gothard, from whence, repassing the 

 chain, I followed the Valais to Bex. I observed gypsum 

 during this tour. 



1st. In the AUee Blanche. 



2ndly. In the valley of Cogne ; that of M. Daubuisson. 



3rdly. In the Val Canaria, at the foot of St. Gothard ; 

 that of Messrs. Freislebon and Von Buch. 



4thly. Near Brigg, in the Valais. 



5thly. At St. Leonard, near Sion. 



6thy. At Sarran, near Martigny. 



7thy. Lastly, at Bex. 



It is from comparing the mineralogical and geological 

 characters of these gypsums, and at the same time of those 

 that I had previously observed in Savoy, and of many others 

 of which I could collect descriptions, that I believe myself 

 able to establish that all belong to one period of formation, 

 or at least to two epochs of that period, which is that of the 

 transition series.* 



I shall consider more at length those which have beea 

 regarded as primitive, so as to expose my motives for not 

 adhering to that opinion. 



A. General characters of the Gypsums of the Alps. 



The greater part of these gypsums are apparently in in- 

 terior texture rather compact than crystalline ; in general, 



* It will hereafter be seen that there is some reason for doubting this 

 conclusion, and believing that their true epoch is rather that of the se- 

 condary series, (Trans.) 



