wn. When strata are
discontinuous, as between Europe and America, no evidence can be derived
from the order of superposition, apart from mineral characters and
organic remains; for, unless strata can be continuously traced, mineral
characters and organic remains afford the only means of classing them as
such or such. As to the test of mineral characters, we have seen that it
is almost worthless; and no modern geologist would dare to say it should
be relied on. If the Old Red Sandstone series in mid-England, differs
wholly in lithological aspect from the equivalent series in South Devon,
it is clear that similarities of texture and composition cannot justify
us in classing a system of strata in another quarter of the globe with
some European system. The test of fossils is the only one that remains;
and with how little strictness this test is applied, one case will show.
Of forty-six species of British Devonian corals, only six occur in
America; and this, notwithstanding the wide range which the _Anthozoa_
are known to have. Similarly of the _Mollusca_ and _Crinoidea_, it
appears that, while there are sundry genera found in America which are
found here, there are scarcely any of the same species. And Sir Charles
Lyell admits that "the difficulty of deciding on the exact parallelism
of the New York subdivisions, as above enumerated, with the members of
the European Devonian, is very great, so few are the species in common."
Yet it is on the strength of community of fossils, that the whole
Devonian series of the United States is assumed to be contemporaneous
with the whole Devonian series of England. And it is partly on the
ground that the Devonian of the United States corresponds in time with
our own Devonian, that Sir Charles Lyell concludes the superjacent
coal-measures of the two countries to be of the same age. Is it not,
then, as we said, that the evidence in these cases is very suspicious?
Should it be replied, as it may fairly be, that this correspondence from
which the synchronism of distant formations is inferred, is not a
correspondence between particular species or particular genera, but
between the general characters of the contained assemblages of
fossils--between the _facies_ of the two Faunas; the rejoinder is, that
though such correspondence is a stronger evidence of synchronism it is
still an insufficient one. To infer synchronism from such
correspondence, involves the postulate that throughout each geologic