But if these hard bodies should be softened in
their substance, or brought into a certain degree of fusion, they
might be adapted mutually to each other, and thus consolidate the open
structure of the mass. Therefore, to prove the present point, we have
but to exhibit specimens of siliceous and calcareous strata which have
been evidently consolidated in this manner.
Of the first kind, great varieties occur in this country. It is,
therefore, needless to describe these particularly. They are the
consolidated strata of gravel and sand, often containing abundance of
feld-spar, and thus graduating into granite; a body, in this respect,
perfectly similar to the more regular strata which we now examine.
The second kind, again, are not so common in this country, unless
we consider the shells and coralline bodies in our lime-stones, as
exhibiting the same example, which indeed they do. But I have a specimen
of marble from Spain, which may be described, and which will afford the
most satisfactory evidence of the fact in question.
This Spanish marble may be considered as a species of pudding-stone,
being formed of calcareous gravel; a species of marble which, from Mr
Bowles' Natural History, appears to be very common in Spain.
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