It is plain that there had been an uniform, deposits of that sand and
tinging earth; and that, however different matter might be successively
deposited, yet that each individual stratum should be nearly of the same
colour or appearance, so far as it had been formed uniformly of the same
subsiding matter. But, in the most uniform strata of red sand-stone,
the fracture of the stone presents us with circular spots of a white or
bluish colour; those little spheres are in all respects the same with
the rest of the stone, they only want the tinging matter; and now it may
be inquired how this has come about.
To say that sphericles of white sand should have been formed by
subsiding along with the red sand and earth which composed the uniform
stratum whether of sand-stone or marl, (for it happens equally in both,)
is plainly impossible, according to our notion of that operation in
which there is nothing mysterious. Those foliated strata, which are of
the most uniform nature, must have been gradually accumulated from the
subsiding sand and earth; and the white or colourless places must have
had their colour destroyed in the subsequent cementing operations.
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