File:The Quarterly journal of the Geological Society of London (13889736199).jpg

PROF. A. H. GREEN ON A SECTION NEAR LLANBERTS.
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grey, with very smooth fracture
not unlike that of the felsite, but
the rock is soft enough to be
scratched by the knife and slightly
soapy to the touch : it contains
many blebs of quartz and fragments
of other minerals and rocks, all very
much altered : it is very decidedly,
but rudely, cleaved, and the clea-
vage-planes bend in a wavy way
round the fragments. The surfaces
bounding this band of rock are
parallel to the laminae of the rock
A. The rock C, that comes next,
is a breccia with a dark grey ma-
trix; the fragments are all flat-
tened and lie with their flat faces in
the same direction ; there is a rude
wavy cleavage with a tendency to
bend round the fragments. We
have here then three bands of
rock, all differing in lithological
character and separated from one
another by parallel and nearly
vertical planes ; one of these bands
(A) is made up of numerous
laminae, each differing from its
neighbour in composition, and these
laminae are aU parallel to one
another and to the planes which
separate A from B, and B from C.
These facts, it seems to me, admit
of only one interpretation. The
rocks are bedded and in a nearly
vertical position ; there is clea-
vage as well, and the cleavage and
bedding coincide ; but while the
flakiness of the rocks B and C is
due to rude cleavage, the plane
separating these rocks from one
another, the plane separating B
from A, and the planes of lamina-
tion in A must, I think, be planes
of bedding.
These flaky rocks occupy the
whole face of the cutting for a space
of about twenty yards, but towards
the north-west end a capping of
conglomerate comes on above them.
The junction slopes down to the