fficient to state that mountains of the two types,
_b_ and _d_, are exceedingly common in all parts of the world; and
though of course confused with others, and themselves always more or
less imperfectly developed, yet they are, on the whole, singularly
definite as classes of hills, examples of which can hardly but remain
clearly impressed on the mind of every traveller. Of the first, _b_,
Salisbury Crags, near Edinburgh, is a nearly perfect instance, though on
a diminutive scale. The cliffs of Lauterbrunnen, in the Oberland, are
almost without exception formed on the type _d_.

3. Slope and wall alternately.

3d. When the elevated mass, instead of consisting merely of two great
divisions, includes alternately hard and soft beds, as at _a_, Fig. 14,
the vertical cliffs and inclined banks alternate with each other, and
the mountain rises on a series of steps, with receding slopes of turf or
debris on the ledge of each, as at _b_. At the head of the valley of
Sixt, in Savoy, huge masses of mountain connected with the Buet are thus
constructed: their slopes are quite smooth, and composed of good pasture
land, and the cliffs in many places literally vertical. In the summer
the peasants make hay on the inclined pastures; and the hay is "carried"
by merely binding the haycocks tight and rolling them down the slope and
over the cliff, when I have heard them fall to the bank below, a height
of from five to eight hundred feet, with a sound like the distant report
of a heavy piece of artillery.

[Illustration: FIG. 15.]

Sec. 19. The next point of importance in these beds is the curvature, to
which, as well as to fracture, they seem to have been subjected. This
curvature is not to be confounded with that rippling or undulating
character of every portion of the slaty crystalline rocks above
described. I am now speaking of all kinds of rocks indifferently;--not
of their appearance in small pieces, but of their great contours in
masses, thousands of feet thick. And it is almost universally true of
these masses that they do not merely lie in flat superposition one over
another, as the books in Fig. 8; but they lie in _waves_, more or less
vast and sweeping according to the scale of the country, as in Fig. 15,
where the distance from one side of the figure to the other is supposed
to be four or five leagues.

Sec. 20. Now, observe, if the precipices which we have just been describing
had been broken when their substance was i