INTRODUCTION. 17 
greatest altitudes of Switzerland, points out to us the mode 
in which nature is operating by decomposition, and the 
attraction of gravitation. When standing on the borders 
of the Mer de Glace, and while crossing its frozen bosom, 
this operation was brought most forcibly to my mind. 
Every moment my ears were saluted with the sound, more 
or less distant, of rocks precipitated from some height into 
the abysses below, and which reverberated over this frozen 
sea. The time may come, when the pinnacles of Mont 
Blane and other mountains, which surround the beauti- 
ful valley of Chaumonie, will have been precipitated to 
their bases, and the debris be so completely carried off as 
to leave, perhaps, that beautiful and fertile spot itself, the 
highest pinnacle of the country, a naked rock, to be 
gazed at from a distance.* 
Perhaps the most difficult point to solve, is that which 
presents itself in the fact, that deposits in high latitudes 
contain animal and vegetable remains, presumed by ana- 
logy to be unable to exist in their temperature at the 
present period. A change in the earth’s axis would, of 
course, affect the temperature of its surface, but whether 
that can take place under any known law, in a sufficient 
degree to effect such a change, has certainly not been 
established. Sir John Herschel has supposed that a 
change of temperature might take place in the change 
of the elliptical orbit of the earth, which becomes gradu- 
ally more circular. t 
* Since writing the above, I have observed the following passage in 
Lyell’s Principles of Geology, vol. 3. ‘‘ Those naturalists who have 
seen the glaciers of Savoy, and who have beheld the prodigious magni- 
tude of some fragments conveyed by them from the higher regions of 
Mont Blanc, to the valleys below, to a distance of many leagues, will be 
prepared to appreciate the effects which a series of earthquakes might 
produce in this region, if the peaks or ‘ needles,’ as they are called, of 
Mont Blanc, were shaken as rudely as many parts of the Andes have 
been in our times,” 
+ Geol. Manual, p. 6. 
Cc 
