116 M. A. Favre on the 
stone, filled with small nummulites. This nummulitic lime- 
stone is surmounted by the Alpine macigno formed by lime- 
stone rocks, more or less marly, associated with some sand- 
stones. This is a formation identical with that which the 
Geological Society of France studied some years ago in the 
Deserts near Chambery. The beds of this macigno, which 
form the bottom of the valley of Reposoir and the base of 
the Montagne des Anes, alternate in very great numbers at 
a time with beds, more or less thick, of Taviglianaz sand- 
stone, which, as I have said elsewhere,* appears to be a kind 
of old voleanic tufa. This rock is associated with cargneules, 
with red limestones, and near the Col de la Tuuviére, we 
find a quartz rock in a mass, which is subordinate to it. 
It is below all these rocks that the great limestone mass 
which forms the Montagne des Anes is situated. It is com- 
posed of a greyish or yellowish limestone, which encloses 
pantacrines, pectens, terebratule, fragments of ammonites 
and belemnites, very easily recognised as to the genus, but 
not to be determined as to the species. 
I do not in general believe in anomalies and exceptions in 
geology; because the phenomena have been too general to 
produce what may be called geological monstrosities. Yet, 
although I have often visited this singular locality, I have al- 
ways come to the same result, and I have always seen the 
superposition of the ammonitic and belemnitic limestones on 
the nummulitic limestones. The observations are very easily 
made, for the Montagne des Anes, as I have said, is insulated 
in the middle of the valley, and we see, on the north as well 
as on the south side, the beds of the Vergys and Pointe- 
Percée dip below it. 
I do not know to what age the formation of this mountain 
should be referred; but I may say, that, in its aspect, it pre- 
sents more relation to the jurassic formation than to any of 
the stages of the cretaceous formation of our country. 
I may state, in conclusion, that it is not the first time that 
more ancient formations, resting on nummulitie formations, 
* Notice of the Geology of the German Tyrol, and on the Origin of Dolo- 
mite.— Bib Univ. (Archives), tom. x., p. 205. 
