of getting time
for available examination of the voluminous works on these subjects,
I thought it best to read nothing (except Forbes's most important
essay on the glaciers, several times quoted in the text), and
therefore to give, at all events, the force of independent witness
to such impressions as I received from the actual facts; De
Saussure, always a faithful recorder of those facts, and my first
master in geology, being referred to, occasionally, for information
respecting localities I had not been able to examine.

CHAPTER XIV.

RESULTING FORMS:--FIRST, AIGUILLES.

Sec. 1. I have endeavored in the preceding chapters always to keep the
glance of the reader on the broad aspect of things, and to separate for
him the mountain masses into the most distinctly comprehensible forms.
We must now consent to take more pains, and observe more closely.

Sec. 2. I begin with the Aiguilles. In Fig. 24, p. 170, at _a_, it was
assumed that the mass was raised highest merely where the elevating
force was greatest, being of one substance with the bank or cliff below.
But it hardly ever _is_ of the same substance. Almost always it is of
compact crystallines, and the bank of slaty crystallines; or if it be of
slaty crystallines the bank is of slaty coherents. The bank is almost
always the softer of the two.[57]

Is not this very marvellous? Is it not exactly as if the substance had
been prepared soft or hard with a sculpturesque view to what had to be
done with it; soft, for the glacier to mould, and the torrent to divide;
hard, to stand for ever, central in mountain majesty.

[Illustration: FIG. 25.]

Sec. 3. Next, then, comes the question, How do these compact crystallines
and slaty crystallines join each other? It has long been a well
recognized fact in the science of geology, that the most important
mountain ranges lift up and sustain upon their sides the beds of rock
which form the inferior groups of hills around them in the manner
roughly shown in the section Fig. 25, where the dark mass stands for the
hard rock of the great mountains (crystallines), and the lighter lines
at the side of it indicate the prevalent direction of the beds in the
neighboring hills (coherents), while the spotted portions represent the
gravel and sand of which the great plains are usually composed. But it
has not been so universally recognized, though long ago pointed out by
De Saussure, that the great