' Horace B. Woodward.[25]
[Footnote 25: This work--published whilst these sheets were going
through the press--gives to the student a detailed view of all the
strata of England and Wales, with their various sub-divisions,
from the base of the Palaeozoic to the top of the Tertiary.]
CHAPTER XXI.
THE QUATERNARY PERIOD.
THE POST-PLIOCENE PERIOD.
Later than any of the Tertiary formations are various detached
and more or less superficial accumulations, which are generally
spoken of as the _Post-Tertiary formations_, in accordance with
the nomenclature of Sir Charles Lyell--or as the _Quaternary
formations_, in accordance with the general usage of Continental
geologists. In all these formations we meet with no _Mollusca_
except such as are now alive--with the partial and very limited
exception of some of the oldest deposits of this period, in which
a few of the shells occasionally belong to species not known
to be in existence at the present day. Whilst the _Shell-fish_
of the Quaternary deposits are, generally speaking, identical
with existing forms, the _Mammals_ are sometimes referable to
living, sometimes to extinct species. In accordance with this,
the Quaternary formations are divided into two groups: (1) The
_Post-Pliocene_, in which the shells are almost invariably referable
to existing species, but some of the _Mammals are extinct_; and
(2) the _Recent_, in which _the shells and the Mammals alike
belong to existing species_.
Pages:
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496