And this shows that the Cheviots had already been
deeply excavated by streams before any portion of the red beds was
deposited.
I have said that the red beds are approximately horizontal; sometimes,
however, they have a decided _dip_ or inclination, and when this is
continuous, it is invariably in a direction away from the hills. Thus
as we traverse the ground from the hill-foot to the Teviot, we pass
over the outcrops of the red beds and slowly rise from a lower to a
higher geological position. The strata, however, are generally so
flat that their dip is often not greater than the average slope or
inclination of the ground. Hence when we ascend the valley-slopes
from the stream, we soon reach the higher beds of the series, as,
for example, in the undulating heights that overlook the Jed in the
neighbourhood of Jedburgh. In that district a number of quarries
have been opened, in which the upper beds of the red series are well
exposed, as at Ferniehirst, Tudhope, etc. These consist of thick beds
of greyish white, yellowish, and reddish sandstones, which, unlike
the crumbling earthy deposits below, are quite suitable for building
purposes. Scales of fish and plant remains are often met with in the
thick sandstones, but the underlying earthy, friable red beds appear to
be quite destitute of any organic remains.
Let us now briefly recapitulate the main facts we have just
ascertained. They are these:--1. All the low grounds that abut upon the
hills are composed of horizontal or nearly horizontal strata, which
consist chiefly of red earthy beds, passing down into conglomerates,
and up into whitish and reddish sandstones. 2. The conglomeratic
portion forms the boundary of the series, fringing the outskirts of the
hills, and resting sometimes upon Silurian strata and sometimes upon
Old Red Sandstone igneous rocks. 3. Fossils occur in the white and red
sandstones, but seem to be wanting in the underlying red earthy beds.
[Illustration: Fig. 7.--S, Silurian strata; _i_, Old Red Sandstone
Igneous Rocks; _a^1_, Conglomerate; _a^2_, Red earthy beds; _a^3_,
White and Red Sandstones.]
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