Professor Pictet on Fossil Bones, 237 



men, and, thanks to his enlightened care, our museum is now 

 possessed of a considerable collection. 



The first point to establish was their geological position.* 



* Professor A. Favre has communicated to me some observations made by 

 him on the repository of these fossils, and the nature of the gravels which con- 

 tain them. 



Note on the graveh containing the fossil hones. 



At first sight, the gravels in which these bones occur, might appear to belong 

 to the lower stage of the diluvian formation of Geneva ; but a more careful ex- 

 amination of the neighbourhood of the hamlet of Mattegnin, shews that the 

 gravels in question form part of the upper stage of this formation. The fol- 

 lowing is the appearance presented by a section of the gravel quarry of Mat- 

 tegnin, going from the upper part downwards. 



1««, One or two feet of vegetable earth. 



2d, Sandy clay, forming a paste with water, named terre a pise, terre blanche 

 or glappe, by the peasants, who use it for building. It contains a pretty consi- 

 derable quantity of rolled pebbles, some of which belong to the crystallized for- 

 mations of the Alps, such as granites, protogines, quartz, crystalline slates, 

 &c., and others consist of limestones, in general of a deep colour. The latter 

 are frequently striated or rayed on the surface, which makes them resemble the 

 rocks polished by glaciers. This bed is variable in thickness ; in the quarry it 

 does not exceed 18 inches, while, at a few hundred metres from that place, near 

 Meyrin, the peasants affirm that it is 10 feet. 



3d;, Gravel or beton, more or less tenaceous, according to the greater or less 

 quantity of stalactitic cement, which solders the pebbles to each other. These 

 pebbles vary greatly, but they are not striated on the surface. We notice every- 

 where beds of sand, very nearly horizontal, which divide this mass of gravel in 

 a more or less regular manner. In the upper parts, these gravels are of ferru- 

 ginous tints ; it is in this bed that the bones are found. Thickness from 10 

 to 12 feet. 



4:th, Coarse clay, remarkably tenacious, forming a paste with water, mingled 

 with a great quantity of different kinds of pebbles. The calcareous pebbles are 

 striated. Although reddish, this bed is often called ivhite earth by the peasants. 

 Thickness not ascertained. 



The gravel containing the bones, therefore, rests upon an argillaceous earth 

 containing striated pebbles. This, as I have mentioned elsewhere (Considera- 

 tions geologiques sur le mont Saleve et sur les terrains des environs de Geneve, 1843, 

 p. 74), is one of the principal characters of the cataclystic diluvian formation. 

 This gravel, then, forms part of this formation, as I undertake to prove. In 

 traversing the environs of Mattegnin, we may convince ourselves that it is a 

 local deposit much less extended than the ancient alluvion which it resembles, 

 and, in its geological position, very like the deposits of sand at Frontenex^ Ma- 

 lagnou, Cartigny, &c., cited by M. Necker, {Etudes Oeologiquet dan* ks Aipts, 

 i. 248, 259, &c.) 



With regard to the ancient alluvion which extends horizontally along the 



