But the observation that is most to the purpose of the present subject
of bituminous strata, is this; it is chiefly in the strata of the flat
country that fossil coal are found; there are none that I know of in
all the alpine countries of Scotland; and it is always among the strata
peculiar to the flat country that fossil coal is found. Now, this
appearance cannot be explained by saying that the materials of mineral
coal had not existed in the world while those primary strata were formed
in the sea. I have already shown, (chap. 4.) that there had been the
same system of a world, producing plants, and thus maintaining animals,
while the primary strata were formed in the sea; I have even adduced an
example of coal strata among those primary schisti, although this be an
extremely rare occurrence: Consequently, we are under the necessity of
looking out for some other cause.
If the changes which have been evidently superinduced in the strata of
alpine countries arise from the repeated operations of subterranean
fire, or to the extreme degree in which those strata have been affected
by this consolidating and elevating cause, it will be natural to suppose
that the bituminous or combustible part among those stratifications, may
have been mostly consumed upon some occasion during those various and
long continued operations; whereas, in the flat beds of the low country,
although there is the most perfect evidence for the exertion of heat in
the consolidation of those strata, the general quantity of this has been
a little thing, compared with the universal manifestation of this cause
in the operations of the alpine countries, the strata of which have been
so much displaced in their situations and positions.
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