80 M. Bkochant on the 



blage of characters that the eye often seizes at the first 

 coup d'ceil, but that are extremely difficult to define. 



2. That all these fragments of quartz, often large and 

 always angular, can only arise from superior rocks, there is 

 every reason to suppose that the schistose limestone of the 

 roof contains quartzose veins, as also happens in transition 

 limestone. 



3. Lastly, I will call to mind the mineralogical relations 

 which unite this gypsum to all the others I have described, 

 and above all to that of Brigg, of St. Leonard, and others 

 that belong to the transition series. 



To all these considerations, that already lead me to refer 

 this gypsum to the same era of formation as those that I 

 have noticed, I shall add another; it is, that the strong 

 difiFereuces of nature and structure, which I have observed 

 in this valley of Cogne, between the rocks of the heights and 

 those of the valley, lead me strongly to suspect that the 

 lower part is a primitive country crowned towards the sum- 

 mits, or at least the lower crests, by transition rocks ; but 

 I could not sufficiently assure myself of this fact to venture 

 to gi\e it as certain. 



7. Gypsum of the Val Canaria. 



This small valley, but two leagues in length, descends 

 nearly from N.E. to S.W. into the high valley in which the 

 Tesino flows; its opening, which is very narrow, is at a short 

 distance from the village of Airolo, at the foot of St. Go- 

 tbard. Following the torrent at first, we find ourselves 

 between enormous masses, and as it were between walls of 

 the micaceous gypsum I have above described. Its stratifi- 

 cation is not very distinct, and varies greatly. I observed 

 beds with all kinds of directions and inclinations ; in some 

 places they were horizontal, some were contorted. 



This first observation struck me, by bringing to ray re- 

 collection similar irregularities in the gypsum of the Taren- 

 taise, and many others. 



