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394 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .Apr. 24,
merate will be found rapidly thinning out, and tlie rest of the bed
composed solely of sandstone of uniform texture without any trace of
conglomerate. (See fig. 2.)
Fig. 2.
In the highest part, however, of this deposit, the strata are almost
entirely composed of conglomerate, and its thickness appears to in-
crease considerably as it proceeds in a south-west direction.
At the Craigs, a short distance above the Craigs quarry, the con-
glomerate is met with in its greatest development. In this locality
three bold headlands occur presenting lofty fronts and perpendicular
escarpments to the east, and from this circumstance the locality de-
rives its name. These consist almost exclusively of the coarse con-
glomerate, and are so nearly related to each other that a geological
description of one will also apply to the other two.
Mid Craig is situated about three hundred yards due west from
Craigs quarry, and under this craig the rocks of the quarry dip.
The lowest portion of it visible consists of a coarse light-red sand-
stone, which in some places is fully five feet in thickness. The
depth of this sandstone and the nature of the rocks which underlie
it cannot be ascertained, owing to the debris which occurs at the base
of the Craigs. The sandstone is succeeded by a bed of conglomerate
about five feet in thickness, and in this conglomerate layers of sand-
stone are met with rarely exceeding six inches in depth, which thin
out very rapidly and again occur at different positions in this bed.
A stratum of sandstone about a foot in thickness succeeds this con-
glomerate, and appears to increase in thickness in the direction of its
dip, which is similar to that of the sandstone at Craigs quarry. Al-
ternate beds of sandstone and conglomerate more or less similar to
the foregoing occur for a considerable height, until the sandstone
disappears and uniform beds of conglomerate alone are met with.
The thickness of these conglomerate beds varies considerably, and
even some of the individual beds differ greatly in thickness at dif-
ferent places.
The fragments which compose the conglomerate consist principally
of whin, both slaty and compact, beside which some portions of sye-
nite and granite are also to be met with. These fragments are all
angular, and devoid of the slightest trace of friction or abrasion of any
kind. In size they vary from a small pea to about six inches in dia-
meter, and some occur much larger, but on an average about a cubic
inch is the size of the greater proportion of the fragments. They are
cemented together by a matrix of fine sandstone which is somewhat