in the Erralie Basin of the Rhone. 259 



of these tliree ciTa,tie species predominate, is thus, beyond 

 the Alps, the same as is observed to exist among the Alpine 

 valleys whence they derive their origin. 



The rocks of Mont Rosa, in like manner, act as if they 

 were one species. They follow very nearly the attraction of 

 the Pennine rocks, and accompany them almost everywhei'e 

 in the state of pebbles ; but they do not follow them to the 

 greatest heights, appearing to prefer the plain or the lov/er 

 sides. Tlie considerably-sized blocks of these rocks are found 

 chiefly in the western part of the basin. The plain of Geneva, 

 and the slopes which bound it, the country of Gex, and par- 

 ticularly the neighbourhood of Nyon, are their true domain. 

 There only we meet with blocks of euphotide from two to 

 five metres in length, and masses of serpentine still longer. 

 Beyond this limit, in tlie eastern part of the Pay de Yaud, 

 and further to the east, blocks of euphotide become very rare ; 

 the most remote I have met with on the sides of the Jura, 

 were found above Neuchatel and Neuveville, and they scarcely 

 reach the dimensions of a metre. The same thing may be 

 said of the serpentines. Both of these rocks, however, and 

 the serpentines in particular, reappear in abundance and in 

 large blocks between Bei-ne and Bourgdorf, where they give 

 a character to an entire region of the basin. With regard to 

 the eclogites, I am acquainted with no large blocks of it. It 

 is usually found in blocks of small size, scarcely measurable, 

 and most frequently in pebbles of very variable dimensions. 



We see that the two regions in which the rocks of Mont 

 Rosa are most abundant, are both on the right of those in 

 which the Pennine rocks predominate. Here, also, Ave again 

 find in the plain a disposition of the ei'ratic rocks Avhich 

 recalls the relative situation of the valleys from which they 

 descended. 



The disti'ibution of the granites of Mont Blanc presents 

 some remarkable characters. We find them, at the same time, 

 at the superior limit of the whole erratic formation, along 

 the left side of the basin, on the heights of Chablais, and 

 along the opposite declivities of the Jura. This latter loca- 

 lity oven a])pcars to be, contrary to all expectation, the spe- 

 cial domain of this rock. From I^a Dole to beyond Soleure, 



