nct as to be largely capable
of separate study. _Geology_,[1] in its strict sense, is the
science which is concerned with the investigation of the materials
which compose the earth, the methods in which those materials
have been arranged, and the causes and modes of origin of these
arrangements. In this limited aspect, Geology is nothing more than
the Physical Geography of the past, just as Physical Geography
is the Geology of to-day; and though it has to call in the aid
of Physics, Astronomy, Mineralogy, Chemistry, and other allies
more remote, it is in itself a perfectly distinct and individual
study. One has, however, only to cross the threshold of Geology
to discover that the field and scope of the science cannot be
thus rigidly limited to purely physical problems. The study of
the physical development of the earth throughout past ages brings
us at once in contact with the forms of animal and vegetable
life which peopled its surface in bygone epochs, and it is found
impossible adequately to comprehend the former, unless we possess
some knowledge of the latter. However great its physical advances
may be, Geology remains imperfect till it is wedded with
Palaeontology,[2] a study which essentially belongs to the vast
complex of the Biological Sciences, but at the same time has its
strictly geological side. Dealing, as it does, wholly with the
consideration of such living beings as do not belong exclusively
to the present order of things, Palaeontology is, in reality, a
branch of Natural History, and may be regarded as substantially
the Zoology and Botany of the past. It is the ancient life-history
of the earth, as revealed to us by the labours of palaeontologists,
with which we have mainly to do here; but before entering upon
this, there are some general questions, affecting Geology and
Palaeontology alike, which may be very briefly discussed.

[Footnote 1: Gr. _ge_, the earth; _logos_, a discourse.]

[Footnote 2: Gr. _palaios_, ancient; _onta_, beings; _logos_,
discourse.]

The working geologist, dealing in the main with purely physical
problems, has for his object to determine the material structure
of the earth, and to investigate, as far as may be, the long chain
of causes of which that structure is the ultimate result. No wider
or more extended field of inquiry could be found; but philosophical
geology is not content with this. At all the confines of his
science, the transcendental geologist finds himself con