of an abbey built on a slope in Wales seven hundred years ago, the
creeping waste has gathered on the uphill side to a depth of seven
feet. The slow-flowing sheet of waste is often dammed by fences
and walls, whose uphill side gathers waste in a few years so as to
show a distinctly higher surface than the downhill side,
especially in plowed fields where the movement is least checked by
vegetation.

TALUS. At the foot of cliffs there is usually to be found a slope
of rock fragments which clearly have fallen from above. Such a
heap of waste is known as talus. The amount of talus in any place
depends both on the rate of its formation and the rate of its
removal. Talus forms rapidly in climates where mechanical
disintegration is most effective, where rocks are readily broken
into blocks because closely jointed and thinly bedded rather than
massive, and where they are firm enough to be detached in
fragments of some size instead of in fine grains. Talus is removed
slowly where it decays slowly, either because of the climate or
the resistance of the rock. It may be rapidly removed by a stream
flowing along its base.

In a moist climate a soluble rock, such as massive limestone, may
form talus little if any faster than the talus weathers away. A
loose-textured sandstone breaks down into incoherent sand grains,
which in dry climates, where unprotected by vegetation, may be
blown away as fast as they fall, leaving the cliff bare to the
base. Cliffs of such slow-decaying rocks as quartzite and granite
when closely jointed accumulate talus in large amounts.

Talus slopes may be so steep as to reach THE ANGLE OF REPOSE, i.e.