168 M.BnoiiGif I ART on the position 



entered that cuts the foot of two mountains, and which 

 consequently exposes their structure. 



That on the right bank which is the lowest, and which is 

 represented almost entirely (fig. 1. pi. 5) shows the sue-, 

 cession of the following rocks, inclined from N. to S., and 

 covering each other. These rocks are, proceeding from the 

 highest to the lowest, 



1st. Green serpentine with diallage homogeneous, but 

 much broken, and a petrosiliceous serpentine. The latter 

 is compact, contains whitish petrosilex, disposed in irregular 

 spots passing into little veins in the green paste. It con- 

 tains cromate of iron, some pyritous points, and very little 

 diallage. 



2dly. Diallage rock (or granitone of the Italians) in thick 

 beds, of tolerably regular size, and situated beneath the 

 serpentine, (see fig. 1. at B.). This diallage rock is com- 

 posed of white and greenish felspar or petrosilex, and shining 

 diallage in very large plates. It offers some varieties, the 

 principal of which are : a. serpentine diallage rock passing 

 into the preceding rock, and only dilTering from it by more 

 silex and the presence of diallage in large plates, b. calca- 

 reous reddish diallage rock of a greenish petro-silex paste 

 with thin winding plates of steatite or greenish talc, and 

 numerous red spots of sublamellar carbonate of lime : dial- 

 lage is rare in it. 



The upper beds of diallage rock, those that immediately 

 follow the serpentine, are of a green paste, which colour is 

 seen to be owing to serpentine. The inferior beds offer a 

 mixture of a deep green, a pale green, a greyish, a white 

 and red colour. The red part is not jasper, but as M. 

 Viviani has observed, it is a red lamellar carbonate of lime. 

 Diallage is there less abundant, and the rock is traversed 

 by veins of calcareous spar. 



3dly. The rock that immediately follows it (at C) is a 

 jasper, generally red but sometimes striped or zoned with a 

 violet and greenish colour. This jasper is very splintery, at 

 least on the superficies of the formation ; it is cleanly strati- 

 fied in beds more or less thick, rarely attaining two deci- 



