114 M. A. Favre on the 
tion of the rocks of this valley be added to the exceptions 
already known, presented by the geology of the Alps, when 
compared with that of other countries? This is what I do 
not undertake to decide ; for it is necessary that exceptions of 
this kind should be established by more than one observer. 
But I may refer, as an example of these anomalies, to the 
localities of St Cassian and Hallstadt in Austria, where we 
find a mixture of orthocera and ammonites ; Petit-Cceur, in the 
Tarentaise, where we see belemnites associated with plants 
of the coal-formation ; the apparent superposition of jurassic 
limestone over the tertiary molasse, which is observed 
throughout a great part of the northern acclivity of the 
Alps, from Savoy nearly to Vienna in Austria; and, finally, 
the fan-shaped structure which, in a great number of locali- 
ties, places the crystalline slates above limestones contain- 
ing belemnites. 
‘ The valley of Reposoir is situate in Savoy, on the left bank 
of the Arve, between the towns of Cluses and Thones; it is 
inclosed between two chains of elevated mountains. That, 
on the north is the chain of the Vergys mountains ; that on 
the south is the chain of Meiry, or La Pointe-Percée, which 
separates the valley of Reposoir from that of Mégéve, the 
prolongation of which occupies the right bank of the Isére be- 
tween Albertville and Montmelian. 
The beds which constitute the chain of Vergys dip very 
nearly to the south-east, while those of the chain La Pointe- 
Percée dip to the north-west. It is the same beds which 
form these two chains, so that the valley of Reposoir, which 
is situate between these two, presents the geological struc- 
ture named structure en fond de bateau. 
The highest peaks of the chain of Vergys reach 2388 
metres above the level of the sea, according to M. Chaix. 
Pointe-Percée, which is the most elevated part of the chain 
to which it gives the name, has never been measured ; but 
I calculate that it rises to 2500 or 2600 metres above the 
sea. Between these two chains of mountains, and conse- 
quently in the centre of the valley of Reposoir, rises a large 
mountain, known under the name of Montagne des Anes. Its 
base at Reposoir is 981 metres (barometric observations made 
