in the Neighbourhood of Chamounix, in Savoy. 73 



which has been uaxaQdi fan-shaped, which is not unimportant 

 in the geology of the Alps. These limestones have been re- 

 ferred to the lias formation ; I myself this year found belem- 

 nites in three different localities ; in Mont Lacha, near 

 Ouches ; near the side of Piget, at the foot of the Glacier des 

 Bois, and near the Chalets of Balme. It is annoying that the 

 imperfect preservation of these fossils does not admit of de- 

 termining them specifically. 



Hitherto it has been impossible to distinguish the upper 

 from the lower part of these limestones, and from this there 

 has arisen much confusion in the mind of geologists as to the 

 stnicture of this portion of the Alps ; and many of them, glad 

 to be supported by the authority of Saussure, are accustomed 

 to say, with him, "We may almost assure ourselves that 

 there is notliing so constant among the Alps as their variety."" 

 {Voyages, ^2^01.) 



Dui'ing the many years that I have been in the habit of 

 visiting these mountains, I have been always convinced that 

 we might much more truthfully affirm that there is a great 

 regularity in this part of the Alps ; that the enormous masses 

 that have been raised upwards are in no respect of an excep- 

 tional character, unless it be in consequence, perhaps, of 

 their size ; and that they may be compared, for their regu- 

 larity, with those of the Jura, the forms of which have been 

 so distinctly described by M. Thuinnann. It ought to be 

 thus ; for volcanic agency has operated in the same manner 

 at all times, and over all the surface of the globe. 



It is with this opinion that I attached myself to the study 

 of the neighbourhood of Chamounix ; and although I have 

 not yet arrived at a definite and complete result, I hope to 

 be able, by adducing new observations, to point out the way 

 to an explanation of this structure, which has been regarded 

 as abnormal. 



I at first endeavoured to discover which was the superior 

 and which the inferior portions of the sedimentary formations, 

 which, along with the transported formation, compose the 

 valley of Chamounix. I began by examining the junction of 

 the belemnitic limestones with the crystalline schists, at the 

 base of the chain of Mont Blanc, and I did this from Forclaz 



