258 Sir R. I. Murchison on the Distribution of the 
raines” in that detritus of the larger valleys which has been 
theoretically referred to old glacier action. 
In descending from the higher Alps into the main or trunk 
valleys, Sir Roderick found many examples of rocks rounded 
on that side, which had been exposed to the passage of 
boulders and pebbles, with abrupt faces on the side removed 
from the agent of denudation, all of them reminding him 
forcibly of the storm and /ee sides of the Swedish rocks over 
which similar water-worn materials have passed. 
Seeing, then, that this coarse drift or water-worn detritus 
is distributed sometimes on the hard rocks, and often on the 
remnants of the old valley alluvia, he believes that the whole 
of the phenomena can be explained by supposing that the 
Alps, Jura, and all the surrounding tracts have undergone 
great and unequal elevations since the period of the forma- 
tion of the earliest glaciers—elevations which, dislodging 
vast portions of those bodies, floated away many huge blocks 
in ice-rafts, down straits then occupied by water, and also 
hurled on vast turbid accumulations of boulders, sand, and 
gravel. To these operations he attributes the purging of 
the Alpine vallevs of the great mass of their ancient alluvia, 
and also the conversion of glacier moraines into shingle and 
boulders. He denies that the famous blocks of Monthey, 
opposite Bex, can ever have been a portion of the left lateral 
moraine of a glacier which occupied the whole of the deep 
valley of the Rhine, as Charpentier has endeavoured to 
shew ; and he contends that, if such had been the case, they 
would have been associated with numberless smaller and 
larger fragments of all the rocks which form the sides of 
the valley through which such glaciers must have passed. 
They are, however, exclusively composed of the granite of 
Mont Blanc ; and must therefore, he thinks, have been trans- 
ported by ice-rafts, which, having been forced with great 
violence through the gorge of St Maurice, served to produce 
many of the strie which are there so visible on the surface 
of the limestone.* 
* Mr Charles Darwin, in a recent letter to the author, adheres to his old 
opinions on this point, derived frsm observations in America, and says: “I _ 
