370 On the Physical Geography of the Alps. 
than a ridge. Although the limestone mountains are in general 
less peaked, in comparison, yet, on account of their destructibility, 
and by the removal of the softer materials, gypsum and clay, they 
sometimes assume very curious forms. Their pinnacles (needles, 
teeth), owing to the continual disintegration, fall in great masses, 
and cause the devastation so much dreaded in their vicinity.* 
In treating of the Causes of the present forms of the Valleys 
and Mountain-chains, it is stated, that both erosion by means of 
rivers and the disintegrating effects of the atmosphere and its pre- 
cipitations, can be considered as having only subordinate influ- 
ence on the formation of the Alpine districts. How (it is asked) 
is it possible for erosion to have effected such equal declivities, 
not only of the valleys, but also of the mountain ranges, an 
such a frequent regularity in the distribution of elevations? How 
could it be possible for an Alpine valley to be excavated by such 
means from the summit of Mont Blanc down to the depth of 
3000 feet (French) ? 
With regard to the sudden expansion of the basins, character- 
izing the transverse valleys of the Alps, it is stated (p. 200), that 
this could not have been the result of violent outbursts of water ; 
it not being possible for water to have collected in great masses 
where no dam was present to restrain it; and, if a dam had once 
existed, it could only have been cut through by a deep gap, and 
not removed entirely, without a trace being left through its whole 
extent. And at page 207, in considering how far great local col- 
lections of water may have been concerned in the formation of 
these valleys, the author observes, that were their figure due to . 
this form of aqueous agency, they must be regarded as cauldron- 
shaped cavities, that gradually became filled with débris, and now 
offer levelled surfaces. But this view is decidedly opposed not 
only by the fact of the very frequent protrusion of the underly- 
ing rock, but by the usual occurrence of the rock-surface at the 
slight depth of 10-12 feet (French ) beneath the superficial gravel. 
That the basin- or trough-like forms especially, that is, the re- 
treating of the sides of the valley on both sides, cannot have been 
effected by the presence of a lake, is sufficiently clear. We 
should otherwise confound the effect with the cause. ‘The ques~ 
tion, whether collections of water have generally occupied these 
cavities, is easily answered in most cases. We usually find —_ 
smaller gravel-beds, that by their equal distribution are decidedly 
shown to have been deposited in standing waters. The inequall- 
ties of the valley-bottoms may, indeed, in many cases be suilicie 
cause for this; but sometimes (for example, near Lengenfeld the 
orm of the ravine immediately following, and the depth © the 
erosion of the river-channel, show that here a stopping of the 
' * A notable example occurs in the case of the Diablerets near Bex. ,' 
