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Vol. 53.. SUPERFICIAL DEPOSITS IX CUTCH. 233
blown sand present, so as to make a greater slope, the weathered
blocks which fell on it from the hills would, under the influence of
the rains saturating the sand below, slip gently forward along the
slope, supported by the underlying sand, till they reached their
farthest destination without sinking to the bottom. Thus the
aeolian deposits have served as the carrier (see fig. 2).
Fig. 2. — Boulder-beds in the north of Patcham.
A = Boulder-beds.
B = Subrecent concrete.
C — Jurassic rocks.
D = Hypothetical former extension of
concrete with boulders.
This explanation is analogous to that made use of by Sir Wyville
Thomson to account for the forward motion of the stone-river in
the Falkland Islands, 1 and, if it be a true one, it is possible that it
may in some cases account for deposits of loose blocks which have
been referred to glacial action. There will always be antagonism
between this process and the running away of the water in definite
channels, and at last, when the slope of the aeolian deposits became too
low, the growth of the mounds would cease and the streams would
begin to sensibly denude the deposits, and even cut channels in the
bed-rock. It might be thought that all along the rain would wash
the sand away and let the boulders drop, but we see that as a matter
of fact it does not

besides which, the boulder itself protects the
sand below it, as in the case of earth- pillars, and what is washed
away above or below will be replaced by the next dust-storm.
(3) Infratrappean Grits.
These deposits, lying as they do below the traps, cannot in strictness
be called superficial, but it will be seen that they were probably of
that character — that is, deposited on the land before the traps
were poured on the top of them. This is what Mr. Wynne says of
them

— 'These form a peculiar, soft, loosely granular, and obscurely
stratified group of earthy and sandy rocks, largely composed of
trappean materials . . .they. are frequently associated with the base
of the stratified traps, but they also occur in separate patches over
the country, and sometimes at a considerable distance from them.
They are clearly beneath the trap in some localities

in others they
fill up hollows in the Jurassic beds, the planes of stratification not
i ' Nature,' vol. xr. (1876) p. 359.
Q. J. G. S. No. 210.