Gelogical Progress. 291 
narrow valley into a broad plain, the more especially as Professor 
Ramsay must admit the diminution in the velocity, and con- 
sequently (under such circumstances) in the excavating power 
of the glacier after this emersion. But this remark will not 
apply to another objection, lately brought forward by M. Desor 
in his work ‘Die Gebirgsbau der Alpen,’ namely, that the 
great lake-basins existed before the Glacial period ; for it seems 
quite as easy for Professor Ramsay to get evidence against this 
conclusion as for M. Desor to do so in its favour. Whatever 
may be the issue of this controversy, we have the satisfaction 
of knowing that, like others of its kind, it will have been the 
means of bringing to light a host of important facts that other- 
wise might have remained unpublished ; and we hope it may 
continue as long as it produces such fruit. 
Another subject has lately occupied the attention of Swiss 
Geologists, in addition to that just noticed, though somewhat 
connected with it, namely, the mode of formation of the Alps. 
The opinion seems to be gaining ground, that this mass of moun- 
tains is the result of a number of independent upheavals of strata 
at isolated points; that there is no such thing as the Alpine 
‘Chain,’ but that the Alps consist of several mountains, or 
central masses’ as they are termed, grouped together more or 
less irregularly. These ‘central masses’ are formed of hard 
erystalline rocks, such as gneiss, mica-schist, hornblende-schist, 
&c. ; and the intermediate valleys consist of newer and softer 
material, chiefly clay-slate of different ages. This theory as- 
~ sumes, of course, that the Alpine valleys are essentially valleys 
of elevation, and not of denudation. But for further details 
we must refer our readers to Professor Theobald’s work on the 
Geology of the Grisons (Graubiinden), and to M. Desor’s book 
just mentioned. 
We thus seem to be making a little progress in theoretical 
knowledge, while in the department of actual acquaintance 
with the structure of the earth’s crust much is being done. 
We find Geological Surveys at work almost everywhere in 
Christendom, even in most of our colonies; and through their 
labours we are obtaining a more extended knowledge of geo- 
logical phenomena, though it must not be forgetten that much 
is due to exploring expeditions like that of the ‘Novara.’ It 
is our function to give in the GHoLoGicaAL Magazine the 
essential features of the results of these surveys; but we shall 
also endeavour to discuss with some freedom the more general 
questions suggested by them, for the future advance of Geology 
must chiefly depend upon successful investigations in distant 
and unexplored countries. 
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