VOLCANOS OF THE HAUTE LOIRE AND THE ARDECHE. 253 
positions of the different alluviums, breccias, gravels, and drifts 
of the country, for nowhere do we find the excavation of valleys 
more marked by older and newer gravels, as well as by the 
position of older and newer lava sheets. Nowhere can we study 
better the masses of conglomeratic alluvia which descended 
the valleys, and are so largely developed at the Dent du 
Marais near Lac Chambon, at Necher and Champeix. Un- 
fortunately when at Issoire I had little time to examine the 
physical position of these various alluvia and drifts, although I 
had notes of localities where certain species of mammalia have 
been found. Two kinds of marmot (Spermophilus and Arctomys), 
have been discovered in drifts or breccias near Issoire, at Paix, 
Coude, and Champeix, and with these were found the lagomys, 
or arctic tailless hare of Siberia, now no longer living in Europe, 
and remains of the mammoth. The caves of Champeix, too, have 
yielded the remains of bear ( Ursus spelceus ), badger ( Meles ), 
and horse. Hysena also has been found in this district. With 
respect to the Pliocene mammalia, they have been found in 
great abundance in the tuffs and breccias of Mont Perrier, and 
with them are Mastodon arvernensis , Elephas meridionalis , 
Rhinoceros etruscus , Hippopotamus major , and the great tiger, 
Machairodus cultridens , most of which occur in the forest beds 
of Norfolk. Mr. Scrope informs us that the researches of MM. 
Croizet, Bravard, and Pomel indicate that the remains of 
mammalia from the bone beds of Mont Perrier belong to suc- 
cessive tertiary epochs, and that there are distinct assemblages 
of species preserved in the different bone breccias ; in short, that 
there are Mont Perrier stratified tuffs and breccias of Miocene 
age containing Miocene animals, and Pliocene tuffs and 
breccias containing Pliocene quadrupeds. But this is not easy 
to understand, for it is evident that the old Miocene basalts, 
which now are found high up upon hills, had been excavated, 
and deep valleys cut through them into the freshwater strata, 
long before the lower bone-bearing gravel drifts and the Mont 
Perrier tuffs which overlie them had been deposited. It seems 
to me that the remains of the Miocene animals in the Mont 
Perrier tuffs were probably washed out of older strata, and were 
buried in the flows of mud which accompanied the later volcanic 
-eruptions which burst out in Pliocene times. There are no 
phenomena in Auvergne so puzzling as these conglomerates and 
breccias. How masses of trachyte from Mont Dore and prisms 
of basalt, unworn, and with their angles uninjured, arrived at 
such positions, as the Puy de Monton, twenty miles from the 
Pic de Sancy, it is very difficult to say. In the neighbourhood 
of these mud breccias, too, it is well to be careful about attri- 
buting the transportation of rock masses to the action of a 
glacier, for in some instances the mud has been washed out and 
