76 M. Brochant on the 



examined the pyramids near the torrent ; the largest is from 

 500 to 600 metres [about 1640 to 1968 feet] in breadth, 

 by about 100 or 120 metres [about 328 to 424 feet] in 

 height. This shape is the more remarkable as it rests upon 

 the edges of beds of a well characterized anthracite forma- 

 tion, * and as the smallest trace of gypsum is not obser- 

 vable in the beds of that rock on either side of each of these 

 pyramids, nor the slightest derangement that may make an 

 association of the two formations presumable. 



The gypsum appears here, as in the Tarentaise, in the 

 neighbourhood of rocks containing anthracite, and to be of 

 a formation posterior to it : it may perhaps be conjectured 

 that these pyramids are the scattered remains of a more 

 considerable deposit which might once have filled the valley. 



3. Gypsum of St. Leonard. 



In order to go from Leuck to Sion in the Valais, we pass 

 at pleasure either the village of St. Leonard, which is ele- 

 vated, or by a lower road on the banks of the Rhone. 

 I knew that gypsum was found in this place, and that it was 

 met with equally on either road. 



My expectations were not disappointed; yet I did not 

 find a stratification so regular as to shew the relative position 

 in a decisive manner ; but I was struck with the presence of 

 anthracite, and its accompanying black argillaceous schist, 

 in the vicinity of the gypsum, and at the same time with cal- 

 careous rocks possessing that true or apparent arenaceous 

 structure, so common in the Tarentaise. 



The irregularity of this association, which might be re- 

 ferred to a falling down of the rocks, did not permit me to 

 assign all with certainty to the same formation ; it neverthe- 

 less afforded a striking resemblance to the gypsum of the 

 Tarentaise and that of the Allee Blanche, which exists in 

 anthracite valleys, and is close to a limestone altogether 

 analogous. 



* I four4d among the fallen masses many pieces of «ntliraeite. 



