in the Neighbourhood of Chamomiix, in Savoy. lb 



the Rafords, in front of the hamlet of Pras. From the time 

 of Saussure {Voyages, § 710), as in the present day, lime- 

 stone is quarried here. This rock forms a scarcely strati- 

 fied mass, which rests on the base of the Aiguilles Rouges, be- 

 low La Croix de Flegere. Ascending above the quarry, in 

 order to examine the line of junction of the formation, I 

 found beds of true slate placed between the limestone and 

 the rocks of crystallization. I recognised the slates as be- 

 longing to the anthraciferous formation. They are the pro- 

 longation of those found at the base of the Aiguilles Rouges, 

 above D'Argentiere, and of those which accompany the an- 

 thracite mines of Coupeau. 



In tracing, as I have done, the geological map of this 

 country, we perceive that from the neighbourhood of the Col 

 de Balme as far as the village of Ouches, that is to say, 

 throughout the whole length of the Valley of Chamounix, 

 there exists, at the southern base of the chain of the Aiguilles 

 Rouges, a band of the anthraciferous formation, which rests 

 on this chain, and which has been subjected to great denuda- 

 tions. In many localities, these rocks contain numerous im- 

 pressions of plants, which are probably identical with the 

 plants of the coal formation, like those of the Tarentaise. 

 The slates of Rafords are in almost vertical beds, and co- 

 vered by the Jurassic limestone. The rock immediately be- 

 low them is a crystalline slate containing some pebbles, 

 and which probably ought to be referred to the Valorsine 

 pudding-stone. 



There is often great difficulty in distinguishing certain 

 parts of the Valorsine pudding-stone, which do not contain 

 rolled pebbles of true crystalline slates. I have seen a sin- 

 gular example above the Valorsine slates, which is covered 

 by a rock identical with a true crystalline slate, and yet it is 

 comprised in the formation of the pudding-stone of Valor- 

 sine. 



This doubtful Rafords rock passes insensibly into a rock 

 which constitutes the greatest part of the Aiguilles Rouges, 

 a species of gneiss, the colour of which has given its name 

 to this chain. 



It is this intimate connection of the crystalline schists with 



