File:The Quarterly journal of the Geological Society of London (12646203124).jpg

NICOL SOUTHERN GRAMPIANS.
185
to hai
mass of red and reddish-grey sandstone, with a conglomerate-bed
consisting of masses of brown porphyry and white quartz. The
strata dip at 75° to S. 45° E., and at the Falls consist of coarse sand-
stones below, of a quartz ose conglomerate in
the centre, and of deep-red, fine shaly beds
above. They are intersected by " backs" or
division-planes, nearly vertical to the bedding,
so that the water removing the softer portions
has left great square ledges projecting like
walls into the ravine. The conglomerate is
also well seen near the Railway- station, dipping
at 65° to S. 42° E., the whole surface being
deeply grooved and smoothed as by glacier-
action. Here also it consists especially of vein-
quartz, with smaller fragments of the clay-
slates on the north, in a reddish-brown basis
of decomposed felspar. Beyond the village the
lower sandstones, dipping at 70°-77° to S. 37°
E., are quarried for building-purposes, and are
in part fine-grained and greyish purple, in part
deeper brown and more shaly.
The next formation is the clay-slate (d), seen
in the deep gorge of the Pass of Leny. The
lowest beds are light-grey greywacke, weather-
ing brown, and composed of distinct grains of
quartz in a basis of decomposed felspar and clay-
slate. These strata dip to N". 37° W., at angles
of 44° to 50°. Above them are red and yellow
slaty beds, some of them almost a pure iron-
ochre, others more arenaceous, dipping at 47°
to N. 17° W., but with some confusion and
uncertainty. Red beds follow, with a distinct
cross cleavage ; but their dip is disturbed and
obscure, probably from a dyke of blue columnar
dolerite, 30 to 40 feet wide, which runs N.
25° E. with a slight dip to the south. Beyond
it are fine-grained grey slates, dipping at 66°
to N. 55° W., but with a cross structure or
cleavage inclined at 20° to N. 35° E.
At this point a marked change takes place
in the position of the strata. The dip is first
25° to N. 20° E., but soon rises to 40° to N.
5° W. Further on, it rises to 67°, N. 37° W.,
and then to 75°, N. 45° W., in curved, irregu-
lar beds of blue slate, with a cross division
or cleavage inclined at 12° to N. 12° E. Grey slates again follow,
dipping at 68° to N. 37° W., and are succeeded by coarse greywackes
in thick beds, dipping at 60° to N. 5°-10° W. This rock is also
intersected by other planes dipping 55° to S. 2h° W., and by well-
marked fissures, lined on the sides by actinolite, running to W. 62° S.
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