ne eddy in its course, it throws down in the
next; all that is _proved_ by the above trial is, that so many tons
of material are annually carried down by it a certain number of
feet.

[50] _Nearly_; that is to say, not quite vertical. Of the degree of
steepness, we shall have more to say hereafter.

[51] The Rossberg fall, compared to the convulsions which seem to
have taken place in the higher Alps, is like the slip of a paving
stone compared to the fall of a tower.

CHAPTER XIII.

OF THE SCULPTURE OF MOUNTAINS:--SECONDLY, THE CENTRAL PEAKS.

Sec. 1. In the 20th paragraph of the last chapter, it was noticed that
ordinarily the most irregular contortions or fractures of beds of rock
were found in the districts of most elevated hills, the contortion or
fracture thus appearing to be produced at the moment of elevation. It
has also previously been stated that the hardness and crystalline
structure of the material increased with the mountainous character of
the ground; so that we find as almost invariably correlative, the
_hardness_ of the rock, its _distortion_, and its _height_; and, in like
manner its _softness_, _regularity_ of _position_, and _lowness_. Thus,
the line of beds in an English range of down, composed of soft chalk
which crumbles beneath the fingers, will be as low and continuous as in
_a_ of Fig. 16 (p. 151); the beds in the Jura mountains, composed of
firm limestone, which needs a heavy hammer stroke to break it, will be
as high and wavy as at _b_; and the ranges of Alps, composed of slaty
crystallines, yielding only to steel wedges or to gunpowder, will be as
lofty and as wild in structure as at _c_. Without this beneficent
connection of hardness of material with height, mountain ranges either
could not have existed, or would not have been habitable. In their
present magnificent form, they could not have existed; and whatever
their forms, the frequent falls and crumblings away, which are of little
consequence in the low crags of Hastings, Dover, or Lyme, would have
been fatal to the population of the valleys beneath, when they took
place from heights of eight or ten thousand feet.

[Illustration: FIG. 19.]

Sec. 2. But this hardening of the material would not have been sufficient,
by itself, to secure the safety of the inhabitants. Unless the reader
has been already familiarized with geological facts, he must surely have
been struck by the prominence of the _be