nt the water trickling down the
sides._

It is not uncommon to find cliffs or crags in inland places, but they
usually show one very striking difference from seaside cliffs. The
seaside cliffs may be nearly vertical, but the inland cliffs are not,
excepting for a little way at the top; lower down a heap of stones and
soil lies piled against the face of the cliff and makes a slope up
which you can climb. If you look at the cliff you can find loose
fragments of it split off either by the action of freezing water (p.
83) or by other causes ready to roll down if sufficiently disturbed.
So long has this been going on that a pile has by now accumulated, and
has been covered with plants growing on the soil of the heap. Our
interest centres in this soil; no one has carried it there; it must
have been made from the rock fragments. When you get an opportunity of
studying such a heap, do so carefully; you can then see how, starting
from a solid rock, soil has been formed. This breaking down of the
rock is called weathering.

[Illustration: Fig. 52. Cliffs at the seaside, Manorbier,
Pembrokeshire]

The same change has gone on at the top of the cliff. Fragments have
split off and the rock has broken {118} down into soil which stops
where it is unless the rain can wash it away. If there are no cliffs
where you live you can see the same kind of action in the banks of the
lanes, in a disused quarry, gravel pit or clay pit. Wherever a
vertical cutting has been made this downward rolling begins and a heap
quickly forms, making the vertical cut into a slope. Plants soon begin
to grow, and before long it is clear that soil has been made out of the
fragments that have rolled down. This process is known as soil
formation, but there is another always going on that we must now study.
The heap does not invariably lie at the foot of the cliff. If there is
a stream, river, or sea at the foot the fragments may be carried away
as fast as they roll down: the differences shown in Figs. 52 and 53
between a cliff at the seaside and a cliff inland arise simply in this
way. In inland districts great valleys are in course of time carved
out, and at the seaside large areas of land have been washed away.

What becomes of the fragments thus carried away by the water? The best
way of answering the question would be to explore one of these mountain
streams and follow it to the sea, but we can learn a good deal by a few
experiments that can