Neither are
these last discoverable below the town of Jedburgh, at least so far as
I have seen; and the line of division, or plane of junction of the
vertical and horizontal strata, appears to decline more than the bed of
the river.
But it may be asked, how the horizontal strata above, among which are
many very strong beds, have been consolidated. The answer to this
question is plain. Those strata have been indurated or consolidated
in no other manner than the general strata of the earth; these being
actually the common strata of the globe; while the vertical or schistus
strata are the ordinary strata still farther manufactured, (if we may be
allowed the expression) in the vicissitude of things, and by the mineral
operations of the globe. That those operations have been performed by
subterraneous heat has been already proved; but I would now mention some
particular appearances which are common or general to those strata, and
which can only be explained upon that principle.
The red marly earth is prevalent among those strata; and it is with this
red ferruginous substance that many of the sand-stone strata are tinged.
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