20 
POPULAR SCIENCE REVIEW. 
tricolor , the parent, probably, of onr garden pansies. The little 
village of Murol is situated on the modem lava current which 
has flowed from the Puy de Tartaret, while the ruins of the 
grand feudal castle tower above on the old basalts from Mont 
Dore. This castle is a most noble and imposing structure still. 
Its position is grand when viewed from below, while its great 
mass, its towered outworks, and massive central tower, impress 
the mind with a sense of solidity and power. It was ransacked 
and ruined in the revolution of 1793. The views on all sides; 
are very extensive, and most remarkable altogether is this 
feudal fortress of Murol. The Lake of Chambon is up the 
valley about a mile, and owes its existence to a dam of lava 
from the Puy de Tartaret, an extinct volcano with two craters 
and a cone made up of volcanic cinders. Most astonishing,, 
too, are the accumulations and breccias of the Dent du Marais. 
Everywhere in this country we are struck with geological phe- 
nomena on the grandest scale. First we remark the flow of the 
old lavas, which form great basaltic platforms high above the 
present valleys ; and yet these basalts and their accompanying 
breccias must once have flowed in valleys which existed before 
the erosion of the present watercourses. Again, the recent lava 
of Tartaret flowed down the existing valley of Chambon when 
it was excavated as it is now, and this lava has been excavated 
by the river to great depth. Thirdly, it is quite evident that 
no glacier has passed down the lower part of the valley since 
the eruption of the cinder cones of Tartaret and d’Eraignes- 
Have we any date, then, of the eruption of these cinder cones,, 
for this will assist us in the glacier history? We have. It is 
recorded by Sir C. Lyell (“ Student’s Elements,” 2nd ed. 
p. 528), that the lava of Tartaret flowed over the alluvium of 
an old valley which contains the remains of the Siberian hare 
(Lagomys), and the fossil horse ; and that the arches of a Roman 
bridge spring from the lava of Tartaret, showing that the 
ravine near St. Nectaire was in Roman times excavated much 
as it is now. Remains, too, of the mammoth have, we under- 
stand, been found in drifts of the river Couze. So it seems 
that the northern animals, the mammoth and lagomys, have 
lived in France since the outbursts of Tartaret. Our space will not- 
permit of further allusion to St. Nectaire than to direct atten- 
tion to its fine old Romanesque church, with an apsidal choir 
and barbaric representations of men and animals in colour, its 
cromlech on a hill-side between the upper and lower baths, and 
the beautiful drive by Champeix to Issoire. The road passes 
through a picturesque gorge on the river Couze. And here we 
strike the old granite basement rock through which burst the 
ancient volcanic masses of the Mont Dore volcano. The lava 
from Tartaret flows down the valley eroded by an ancient Couze,, 
