of Serpentine, S^c. in the Apennines. 167 



very hard, mixed with crystalline quartz and brown ochre 

 or umber earth, which appears to be an alteration either of 

 jasper or of manganesiferous red schist. 



I shall not enter further into details respecting the rocks 

 composing these formations ; many of them have been well 

 described by the Italian geologists, Messrs. Viviani, Bardi, 

 Brocchi, &c. and by the French geologists, Messrs. Faujas, 

 Cordler, &c. 



It is moreover for naturalists who live on the spot deeply 

 to study these details, that require time and frequent visits 

 to the same canton. I do not therefore pretend to have 

 completed this description, but to have sufficiently studied 

 it for my object. 



I ought now to shew the manner in which these rocks and 

 formations occur together. 



Article II. 



Disposition of these rocks with regard to each other. 

 Sect. I. Directly and closely observed. 



I have recognised these relations in three principal places, 

 separated, in a right line, more than thirty leagues from each 

 other ; and this positive knowledge being acquired, I have 

 been afforded the means of recognising the same mode of 

 occurrence in places where it was not so evident, and to 

 content myself with analogies, the value of which I now 

 appreciate, in order to apply it to other foundations in 

 which this disposition is shewn in an incomplete manner. 



The first place where the relative position of the three 

 formations is shewn in a perfectly clear manner, is the small 

 valley of Cravignoli, leading from Borghetto to the village 

 of Rochetta; this village is situated at about 13 kilometres 

 [11 1 miles] to the north of Borghetto and Brugiiato, and at 

 56 kilometres [about 42y miles] in a direct line to the 

 .N.N.E. of Spezia. 



Following the bed of the torrent of Cravignola, a gorge is 



