PIIIMITIVE GYPSUM. "^^3 - 



iri^tyf shall begin with'a iTeWNs'or^s on the mineral con- 

 stitution of thetountry around. 



The southern declivity of the Alps, from Mount Blanc Southern de. 



to Mount Rose, belono-s almost wholly to the micaceous ^j'/''^ ^^^^*^ 

 ' s» •' _ Alps. 



schist formation. Here, as in other places, this schist fre- 

 quently includes strata of primitive limestone, serpentine, 

 chlorite, oxidulated iron, &c. Sometimes it passes into 

 argillaceous schist, as at the col de TAllee Blanche for in- 

 stance ; but still more frequently into gneifs and granite. 



About 15000 met, [9 miles] south of the town of Aoste, Mountain near 

 and to the east of the village of Cogne, which is at its foot, °S»«» 

 rises a mountain, that forms part of the chain separating 

 the valley of Cogne from that of Fenis« It is terminated by 

 a sharp ridge at least 700 met. [765 yds.] above the bottom 

 of the valley. Its absolute height appears to me nearly to 

 equal that of the passage of the Great St, Bernard, or 

 2400 met. [2623 yds.] above the level of the sea, It pro- 

 bably rests on the granite, that shows itself on the Surface 

 2 or 3 kilom, [10 or 15 furl.] to the north. It is composed 

 of micaceous schist, in strata very slightly inclined, so that 

 they may be considered in general as horizontal. In its 

 upper part the micaceous schist becomes loaded with lime- 

 stone, so that in some little places it ends with being nothing 

 but a white granular limestone containing merely a few 

 spangles of mica. It includes also considerable strata of 

 serpentine, in one of which is the celebrated iron mine of 

 Cogne*. 



T!ie stratum of gypsum is found 20 met. [23 y<is.] below stratum of 

 the highest point of the ridge. It is exposed only to the gypsum. 

 length of 7 or 8 met. and 1 met. thick. Throughout the 

 rest of its extent it is concealed by the numerous fragm«fnt3 

 of stone, that have fallen from the sumflriit, and cover the. 

 aides of the raoi:^ntain in this part : so that I can say nothing 



♦ This mine, perhaps the richest in the world, exhibits the appearance Rich iron 

 of an iron quarry, which is worked in open dr.y. The ore is oxidu- mine, 

 lated iron, in some places pure. It is in fery small grains, and some- 

 limes wholly compact. It forms a mass, that appeared to me to be a very 

 short and thick bed. Where it is worked it i« more than 25 met. [27 

 yds2 thick, 



of 



