4 DR. J. W. GREGORY ON THE * SCHISTES [Feb. 1 896, 



laid down later, and upon the others. In fact, what according to 

 Zaccagna is the oldest rock in the mountain, according to Bertrand 

 is the newest. 



The differences, moreover, are as important as they are absolute. 

 According to Bertrand, the ' schistes lustres ' pass laterally into the 

 Trias (see op. cit. fig. 2, p. 123, and fig. 9, p. 135). According to 

 Kilian the presence of the * schistes lustres ' seems to exclude the 

 presence of the Carboniferous, and he therefore suggests that the 

 4 schistes ' may be Carboniferous ; though he admits that this cannot 

 be definitely determined. If, however, Zaccagna and Lory be correct, 

 and the central rocks of Mont Jovet are 'schistes lustres,' then these 

 occur surrounded by both Carboniferous and Triassic rocks. In 

 that case, it cannot be maintained that the ' schistes lustres ' are 

 the eastern metamorphosed condition of the beds which farther 

 west have remained as non-foliated sediments. 



The identification of any ' schistes lustres ' in Mont Jovet would 

 therefore alone be fatal to the view that these rocks are Carboni- 

 ferous or post-Carboniferous in age. Having failed on previous 

 occasions to obtain definite proofs of the pre-Carboniferous age of 

 the ' schistes lustres ' in the Cottian Alps, I was the more im- 

 pressed by Bertrand's reversion to Lory's theory. The perusal of 

 Bertrand's paper did not carry conviction ; but respect for the 

 care and ingenuity with which the author had solved the puzzling 

 problems of Provengal geology necessitated the careful consideration 

 of his views. I therefore resolved to visit Mont Jovet as soon as 

 the melting of the snow rendered geological work possible, and exa- 

 mine the mountain independently in order to see whether it does 

 contain any ' schistes lustres ' ; and, if so, to try to construct a more 

 detailed geological map than has yet been published. . So much, 

 however, of the mountain is covered by pine-forest and talus, by 

 moraine and meadow, and so many of the important junction-lines 

 are thus hidden, that it was impossible to make a geological map 

 sufficiently complete to repay the time which it would occupy. I had 

 therefore to be content with a sketch-map based on the French 

 Ordnance survey on the scale of 1 : 80,00c). 1 



Standing on the hills on the northern side of the Isere, at any 

 good point of view between Moutiers and Aime, the southern side 

 of the valley is seen to consist of three main divisions. The lowest 

 part is formed of steep cliffs of dark-coloured rocks, covered by 

 vineyards, meadows, and woods. Above this is a belt of pine-forest ; 

 in this occur at intervals cliffs of buff dolomite and white gypsum, 

 and occasional crags and pinnacles of the former rock. Above this 

 belt are the high-level pastures, formed of undulating meadow-land 

 passing up into irregular rock-strewn slopes, and a group of peaks, 

 of which the highest is Mont Jovet. Further examination of this 

 mountain-mass shows that these three zones are each formed by 

 different series of deposits. The lower slopes are occupied by Car- 



1 ilbertville, S.E.'feuille 169 bis, type 1889. 



