Vol. 58. j ALPINE VALLEYS.IN RELATION TO GLACIERS. 693 
begin to form at 7000 feet, and the extent of the ice-streams would be 
enormously increased. For instance, in the valley above Saas Grund 
a field of névé would extend down from the Monte-Moro Pass to 
below the Mattmark Inn, and in the Oberland a continuous snowfield 
would cover the upper part of the Gemmi Pass. 
These conclusions are inevitable, if we believe the climate of 
Europe to have been warmer than now in Oligocene, Miocene, and 
early Pliocene times, especially in the first and second. They may, 
however, be questioned on the ground that the Alps were then 
more elevated than at the present time, and have since been greatly’ 
lowered by ‘denudation.’ ‘This objection demands an answer. No 
doubt a great mass of material has been removed; valleys have 
been carved out in rock-masses once continuous; their floors have 
been much lowered ; but is there any evidence that the height of 
the crests has been very materially diminished? Suppose the Alps 
—say at the outset of the Oligocene—to be beginning to rise, and 
their watershed to correspond on the whole with that of the 
Pennines. No sooner did that emerge, than streams would begin 
to run northward and southward. Some might trace for themselves 
independent parallel furrows; most of them would combine in 
groups, like the branches and trunk of a tree, as we can see when 
the tide retreats from a shelving, sandy shore. Suppose subordinate 
folds to be presently developed on the north and south of the main 
one; then streams would be caught by the intervening troughs, 
and valleys of strike’ be formed. But the water in places would 
escape through a gap in the crest of the subordinate fold, for it is 
very probable that this would not keep at the same level in 
every part. ‘These outlets, as the rising continued, would probably 
become less numerous, so the water would ultimately escape from 
the central range (as at the present day) by very few gaps.” This 
would be the early history of the great strike-valleys of the Upper 
Rhine, Reuss, and Rhone—that extraordinary trough of (mostly) 
Mesozoic rock now divided into three by the comparatively low 
watersheds of the Oberalp and the Furka.’ The rising in the Swiss 
Alps was not marked till, at any rate, after Bartonian times, and 
must have been going on during the earlier part of the Oligocene. 
The great conglomerate-masses of the Nagelfluh, now generally 
referred to the Upper Oligocene, prove denudation to have then 
become active, and that which now forms the Rigi indicates the 
course of the Reuss through the Bernese Oberland to have been 
already determined, although the crystalline rocks, which we now 
see rising from beneath the Mesozoics and later sedimentaries at 
1 T prefer the old terms ‘ dip-valleys’ and ‘strike-valleys’ to the more modern 
‘consequent’ and ‘ subsequent,’ as on the whole more expressive. ‘ Obsequent,’ 
another new term, ought not, I believe, to bear the meaning given to it. 
* Four: the Rhone, the Reuss, the Rhine, and the Inn. 
* Oberalp Pass (6710 feet), Furka Pass (7990 feet): probably it may be traced 
over the Forclaz (4937 feet) and the Col Ferret (8343 feet), where, however, it 
is deranged by the massif of Mont Blane. 
