e.

[57] Some terrific cuts and chasms of this kind occur on the north
side of the Valais, from Sion to Briey. The torrent from the great
Aletsch glacier descends through one of them. Elsewhere chasms may
be found as narrow, but few so narrow and deep.

CHAPTER IV.

OF THE FOREGROUND.

We have now only to observe the close characteristics of the rocks and
soils to which the large masses of which we have been speaking, owe
their ultimate characters.

Sec. 1. What rocks were the chief components of ancient landscape
foreground.

We have already seen that there exists a marked distinction between
those stratified rocks whose beds are amorphous and without subdivision,
as many limestones and sandstones, and those which are divided by lines
of lamination, as all slates. The last kind of rock is the more frequent
in nature, and forms the greater part of all hill scenery; it has,
however, been successfully grappled with by few, even of the moderns,
except Turner; while there is no single example of any aim at it or
thought of it among the ancients, whose foregrounds, as far as it is
possible to guess at their intention through their concentrated errors,
are chosen from among the tufa and travertin of the lower Apennines,
(the ugliest as well as the least characteristic rocks of nature,) and
whose larger features of rock scenery, if we look at them with a
predetermination to find in them a resemblance of _something_, may be
pronounced at least liker the mountain limestone than anything else. I
shall glance, therefore, at the general characters of these materials
first, in order that we may be able to appreciate the fidelity of
rock-drawing on which Salvator's reputation has been built.

Sec. 2. Salvator's limestones. The real characters of the rock. Its
fractures and obtuseness of angles.

The massive limestones separate generally into irregular blocks, tending
to the form of cubes or parallelopipeds, and terminated by tolerably
smooth planes. The weather, acting on the edges of these blocks, rounds
them off; but the frost, which, while it cannot penetrate nor split the
body of the stone, acts energetically on the angles, splits off the
rounded fragments, and supplies sharp, fresh, and complicated edges.
Hence the angles of such blocks are usually marked by a series of steps
and fractures, in which the peculiar charact