But let us suppose that no fruit, seed, or flower had ever been met with in a
fossil state, we should still have been indebted to the persevering labours of
botanical palaeontologists for one of the grandest scientific discoveries for
which the present century is remarkable-- namely, the proofs now established of
the prevalence of a mild climate and a rich arborescent flora in the arctic
regions in that Miocene epoch on the history of which we are now entering. It
may be useful if I endeavour to give the reader in a few words some idea of the
nature of the evidence of these important conclusions, to show how far they may
be safely based on fossil leaves alone. When we begin by studying the fossils of
the Newer Pliocene deposits, such as those of the Upper Val d'Arno, before
alluded to, we perceive that the fossil foliage agrees almost entirely with the
trees and shrubs of a modern European forest. In the plants of the Older
Pliocene strata of the same region we observe a larger proportion of species and
genera which, although they may agree with well-known Asiatic or other foreign
types, are at present wanting in Italy.
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