in the Erratic Basin of the Uhone. 251 



size. It is tliese chlorites which I have hitherto named 

 roches de Bagnes, because they constitute, in a considerable 

 degree, the great chains which traverse the upper part of this 

 valley and its neighbourhood. 



These three species are found too uniformly together 

 throughout the whole extent of the basin of the Rhone not 

 to have primitively belonged to the same localities. They 

 form a group by themselves, which I shall call, by way of 

 eminence, the Pennine rocks ; for I have satisfied myself that 

 it is in the highest summits of the Pennine Alps that they 

 have their primitive seat. 



M. De Chai'pentier had announced, on hearsay, that arke- 

 sine, or talcose granite, came from the Valley of Binnen, in the 

 Haut-Valais, and especially from the chain which separates 

 this valley from Yal-Antigorio. I have traversed this valley, 

 and the Col de Albrun, which leads to Antigorio, without 

 meeting with a single fragment which reminded me of this 

 well-marked rock. MM. Studer, Escher, and Desor, have 

 examined the two chains which border this valley, from Va- 

 lais as far as Val-Divedro, without finding it. I was there- 

 fore ignorant, when starting on my last expedition among 

 the Alps, whither I should go to seek for it. Guided by the 

 law of distribution which I had recognised in the plain, and 

 by the constant association of this rock with those of Mont 

 Rosa, I directed my steps to the bottom of the valleys of this 

 enormous mass, and thei'e, above the Glacier of Zmutt, I at 

 last found it in great abundance, forming a vast moraine on 

 the left flank of the valley, at the very limit of the polished 

 rocks, at a height of 9000 feet. This train, which I followed 

 for the space of a league, evidently came fi'om the near re- 

 gions of the Dent Blanche and Dent d'Erin. 



I ao-ain found the arkesine in the Val d'Erin in equal abun- 

 dance. The only two specimens of this rock in the rich col- 

 lection at Berne, were brought, the one from these same 

 regions of the Dent d'Erin, where it was found by M. Forbes, 

 the other from the bottom of the valley of Bagnes, from the 

 Glacier of Chermontane, where it was procured by M. Studer. 

 At the Glacier of Zmutt, as in the Val d'Erin, the chloi-itic 

 gneiss, with all its varieties, accompanies the arkesine. We 



