rtion of the intensity of the forces
which have been in operation. If, in the ancient world, mud and sand
accumulated on sea-bottoms at tenfold their present rate, it is clear
that a bed of mud or sand ten feet thick would have been formed then in
the same time as a stratum of similar materials one foot thick would be
formed now, and 'vice versa'.

At the outset of his studies, therefore, the physical geologist had to
choose between two hypotheses; either, throughout the ages which are
represented by the accumulated strata, and which we may call 'geologic
time', the forces of nature have operated with much same average
intensity as at present, and hence the lapse of time which they
represent must be something prodigious and inconceivable, or, in the
primeval epochs, the natural powers were infinitely more intense than
now, and hence the time through which they acted to produce the effects
we see was comparatively short.

The earlier geologists adopted the latter view almost with one consent.
For they had little knowledge of the present workings of nature, and
they read the records of geologic time as a child reads the history of
Rome or Greece, and fancies that antiquity was grand, heroic, and unlike
the present because it is unlike his little experience of the present.

Even so the earlier observers were moved with wonder at the seeming
contrast between the ancient and the present order of nature. The
elemental forces seemed to have been grander and more energetic in
primeval times. Upheaved and contorted, rifted and fissured, pierced by
dykes of molten matter or worn away over vast areas by aqueous action,
the older rocks appeared to bear witness to a state of things far
different from that exhibited by the peaceful epoch on which the lot of
man has fallen.

But by degrees thoughtful students of geology have been led to perceive
that the earliest efforts of nature have been by no means the grandest.
Alps and Andes are children of yesterday when compared with Snowdon and
the Cumberland hills; and the so-called glacial epoch--that in which
perhaps the most extensive physical changes of which any record
remaining occurred--is the last and the newest of the revolutions of the
globe. And in proportion as physical geography--which is the geology of
our own epoch--has grown into a science, and the present order of nature
has been ransacked to find what, hibernice, we may call precedents for
the phenomena of the past, so