of Devonshire and Cornwall. 139 



mineralogists, as occurring in the oldest serpentine, as much as that 

 at Chiavenna and elsewhere. 



There is a little way below the Pass-cTOlen^ a ridge connected 

 with the main body of Monte Rosa itself, a bed of magnetic iron* 

 which is worked, though situated at the height of eight thousand 

 eight hundred and fourteen feet above the level of the sea, so that 

 without going out of the boundary of this mountain we find argu- 

 ments supported by certain facts, proving that the characters which 

 have been pointed out as distinguishing the two kinds of formation, 

 are not well founded. Cornwall furnishes an example no less con- 

 clusive, as we find at the most southern point of the Lizard, the 

 serpentine resting on mica slate, though it appears as if occurring 

 there in mass. 



Of all the characters which have been considered, I see only one, 

 upon which we can rely in establishing a division in the serpentine 

 formation, if such a division be at all necessary, viz. that the 

 serpentine is found either stratified ; or in mass, in balls, and 

 forming subordinate beds. All the other circumstances which have 

 been hitherto thought to characterize the one or the other of these 

 formations, appear to me to belong to both indijfferently. It 

 is probable that there may be some reason for admitting a differ- 

 ence of age in the serpentine formation, but on what ground this 

 distinction is to be admitted, does not appear. It is a subject 

 which among a great many others ought to excite the attention 

 of those who are interested in the study of the physical structure 

 of our globe. Let us imitate the example of the most skilful 

 geologists, of Pallas, and of Saussure, who without ever losing 



* Brochant also mentions this mine ; he calls the Pass-d'Olen the Col (fOlivgue. 

 Traite de Mineralogie, torn. ii. p. 278. 



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