ancient Gypsum of the Alps. 81 



Large angular blocks of mica slate are seen on the banks 

 of the torrent, some mixed with garnets, and others with 

 hornblende. I took the greatest pains in searching for the 

 beds of mica slate, which were stated to be associated with 

 the gypsum, but I could not discover the slightest trace of 

 it. The gypsum is there, as in many other places, abso- 

 lutely isolated. 



It was nevertheless possible that this association of gyp- 

 sum with mica slate occurred towards the top of the slopes, 

 and as it was announced (Itineraire du St. Gothard, p. 73.) 

 that the gypsum continued on the south towards the Val 

 Piora, I preferred ascending the mountain on my right, 

 that is to say, on the left bank of the torrent. I had ob- 

 served this mountain from Airolo ; I had remarked that 

 its rocks were most frequently naked, and that their highly 

 inclined beds appeared in their direction to cut those of the 

 valley ; I was then assured, that in crossing these beds, I 

 should meet with gypsum, if it were true that it was subor- 

 dinate to the mica slate. 



After half an hour of a very steep ascent, always on 

 gypsum, I arrived at a more even surface, only slightly in- 

 clined towards the valley ; ascending the valley, I follow- 

 ed for some time this species of plain, and observed on its 

 surface a great many of those holes and funnels so common 

 in the gypsum rocks. * I soon turned and continued to 

 ascend the slope, but I almost immediately found that I 

 quitted the gypsum ; and when I was a little more elevated 

 so as to be able to command the bottom of the valley, I saw 

 clearly that the gypsum did not extend very far along its 

 bottom, but that it was no where elevated above the height 

 I had quitted ; that it only filled up the bottom of the 

 valley, resting on both slopes, and that the small valley, or 

 rather inferior ravine, was hollowed out of its mass. I as- 

 sured myself the next day that the structure on the other 

 side was similar. 



• The like exist in the gypsum deposit of the Tarentaise, near the lake 

 of Tines. 



F 



