So that the
number of intermediate and transitional links, between all living and
extinct species, must have been inconceivably great. But assuredly, if
this theory be true, such have lived upon the earth.
ON THE LAPSE OF TIME, AS INFERRED FROM THE RATE OF DEPOSITION AND EXTENT OF
DENUDATION.
Independently of our not finding fossil remains of such infinitely numerous
connecting links, it may be objected that time cannot have sufficed for so
great an amount of organic change, all changes having been effected slowly.
It is hardly possible for me to recall to the reader who is not a practical
geologist, the facts leading the mind feebly to comprehend the lapse of
time. He who can read Sir Charles Lyell's grand work on the Principles of
Geology, which the future historian will recognise as having produced a
revolution in natural science, and yet does not admit how vast have been
the past periods of time, may at once close this volume. Not that it
suffices to study the Principles of Geology, or to read special treatises
by different observers on separate formations, and to mark how each author
attempts to give an inadequate idea of the duration of each formation, or
even of each stratum. We can best gain some idea of past time by knowing
the agencies at work; and learning how deeply the surface of the land has
been denuded, and how much sediment has been deposited. As Lyell has well
remarked, the extent and thickness of our sedimentary formations are the
result and the measure of the denudation which the earth's crust has
elsewhere undergone.
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