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Vol. 58.] ALPINE VALLEYS IN RELATION TO GLACIERS. 701 
as to become wearisome. ‘These can be produced, if necessary. So 
I venture to conclude this communication, already somewhat prolix, 
by a brief statement of the ideas concerning the valley-sculpture of 
the Alps, which have gradually developed themselves in my mind 
from a study not of books, but of Nature, in the course of visits, which 
are now 30 in number. This sculpture began in Oligocene ages, 
when the central axis, which still forms the watershed, dominated 
greatly over the ranges north and south ; it continued through most 
of the Miocene, though it was at its maximum, at any rate in the 
transport of materials, when the Nagelfinh pebble-beds were deposited ; 
for during these periods the rainfall on the Alps, owing to the 
different arrangement of sea and land, was probably heavier than it 
is at the present time. At first there were no glaciers, for some 
time not even permanent snow-beds. Then denudation—peak- and 
valley-sculpture alike—was of the ordinary kind, which became 
more active as the temperature slowly declined. The Miocene 
Period, as it approached its end, would witness two changes: (a) the 
beginning of the second great Alpine uplift; (0) a marked extension 
in the area permanently covered by snow, and thus the formation 
of real glaciers.’ This second change would restrict, or even arrest 
the action of small streams in the upper glens, and would intensify 
that of the main torrents; in other words, there would be less 
rake-scratching in the upland glens, and more furrow-cutting in the 
valleys. ‘he latter process would become more conspicuous during 
the Pliocene, as the glaciers continued to increase in size; but it 
must be remembered that, as the ice occupied more and more of a 
valley-floor, it would protect the newly-annexed territory from 
other agencies than the ice-plane.* In a system of valleys, denu- 
dation would be checked on the whole in the higher tributaries, and 
intensified in the principal channels of discharge. This would lead 
to the formation of ‘ hanging valleys,’ and as they developed the 
torrents from them would acquire a plunging force and begin to cut 
gorges.’ This process in many cases has continued ever since, 
though perhaps it might slacken in the higher regions when the ice 
had a very great extension: for at the present day the torrents 
which flow from glaciers are much reduced in volume during the 
winter. That season I presume may be regarded as a temporary 
relapse into the climatal conditions of the Ice-Age.* Therefore I 
maintain that not only does Prof. Davis’s hypothesis derive little 
1 This would be when the mean temperature of the Alpine region (supposing 
the height to be the same) was 6° or 7° Fahr. higher than it is at the present 
day. 
2 The main sub-glacial torrent, especially if it had already cuta gorge, would 
of course continue to deepen this. ; 
3 It is worth noting that in the Alps when streams at the present day are fed 
by lakelets or snow-beds, gorges, as a rule, are insignificant or absent; the great 
gorges, at any rate in the crystallines, are the paths of glacial torrents. 
4 The streams would have great erosive force during inter-Glacial times (when 
the Deckenschotter and the great valley-gravels were formed); but, so far as 
I can judge, the glaciers would even then extend beyond their present limits, 
and thus the districts with which I have been chiefly concerned may have been 
more or less covered by snow or ice all through the Glacial Epoch. 
