g^5 GEOLOGICAL OBSERVATIONS I\ FRANCK. 



to be granitic : the same kind of soil too, that we meet with 

 in going down the Rhone from Lyons by the way of Vieinld 

 and Tonrnon, occurs when we proceed to Beaujolois by 

 way of Tarare, Thizi, and la Claire : thus from the consi- 

 derable extent ocx^upied by this kind of soil in these coun- 

 tries the centre of all these chains cannot be far distant, and 

 it is not without reason, that Mr. Delametherie places it in 



TheCevennes. the Cevennes, which he considers as one of the principal 

 centres of the primitive mountains of France. 



M«untain of rjy^^ ^,^^^ ^j^^^ composes the mountain of St. Bonnet-le- 



S». Bonnet. . . ^ . 



Froid is an undulated reddish gneiss, evidently strutitied, 



and intersected by strata or ve.ns of other rocks, particularly 



white quartz, and schistose hornblende, which assumes a 



porphyritic appearance mi the back of the mountaiiv to the 



West, particularly between the villages of Conrsieux and 



Ste Foy-l' Argentic re. Throughout the whole district of the 



latter, situate in a valley watei-ed by the little river Bre- 



Coat. venne, pitcoal is found. Among the fruit-trees surrounding 



Chesnuts* the houses a few chesiiuts are to be seen, but all of them 



. poor and low : probably thistree will not thrive without sheU 



ter. 



Vines and -waU On the back of the mountain of St. Bonnet, toward 



nutsc ligema . (;;p^^g;gQj^_^ these are some tine plantations of vines; and in 



the bottom of the valley very line walnut trees. This, is not 



the only place where [ have observed the vine and the walnut 



thriving- together ; probably therefore they require nearly a 



similar temperature. 



Holly The holly is common among the firs in the mountains of 



till the Lyonuois, "und sometimes appears as a tree ten or eleven 



and smooth ^^^^ high. In these cases the upper leaves are smooth, while 



leaved at top., the lower ones are prickly as usual. 



Lake diminish- The plain of Forez is covered with a multitude of ponds, 



e<Uo i>oads. ^^^^ ^^ doubt formerly was one extensive lake. In it there 



Basaltic moun- is a basaltic mount/m. The level of this plain is 185 feet 



lain. below that of Limagne. Its soil is evidently formed by the 



decomposition of the primitive rocks; but it appears per- 



Wood sorrel, fectly adapted to wheat. One weed only infests all the fields, 



the wood sorrel; but this is in great abundance, particularly 



ou the i'aliows : hov/ever it is betieficial to the sheep folded 



on 



