scattered fragments or dust in the
neighborhood. Sometimes the mountain is simply broken in two, and the
pieces correspond to each other, only leaving a valley between; but more
frequently one half slips down, or the other is pushed up. In such
cases, the coincidence of part with part is sometimes so exact, that
half of a broken pebble has been found on one side, and the other half
five or six hundred feet below, on the other.

Sec. 14. The beds, however, which are to form mountains of any eminence are
seldom divided in this gentle way. If brittle, one would think they had
been broken as a captain's biscuit breaks, leaving sharp and ragged
edges; and if tough, they appear to have been torn asunder very much
like a piece of new cheese.

The beds which present the most definite appearances of abrupt fracture,
are those of that grey or black limestone above described (Chap. x. Sec.
4), formed into a number of thin layers or leaves, commonly separated by
filmy spreadings of calcareous sand, hard when dry, but easily softened
by moisture; the whole, considered as a mass, easily friable, though
particular beds may be very thick and hard. Imagine a layer of such
substance, three or four thousand feet thick, broken with a sharp crash
through the middle, and one piece of it thrown up as in Fig. 11. It is
evident that the first result of such a shock would be a complete
shattering of the consistence of the broken edges, and that these would
fall, some on the instant, and others tottering and crumbling away from
time to time, until the cliff had got in some degree settled into a
tenable form. The fallen fragments would lie in a confused heap at the
bottom, hiding perhaps one half of its height, as in Fig. 12; the top of
it, wrought into somewhat less ragged shape, would thenceforth submit
itself only to the gradual influences of time and storm.

[Illustration: FIG. 11.]

[Illustration: FIG. 12.]

I do not say that this operation has actually taken place. I merely say
that such cliffs do in multitudes _exist_ in the form shown at Fig. 12,
or, more properly speaking, in that form modified by agencies in
visible operation, whose work can be traced upon them, touch by touch.
But the condition at Fig. 12 is the first rough blocking out of their
form, the primal state in which they demonstrably were, some thousands
of years ago, but beyond which no human reason can trace them without
danger of error. The cloud fastens upon them th