There is as yet no certain indication of the
presence of Conifers. It is a sombre and monotonous vegetation,
unlike any to be found in any climate to-day.
We will look more closely into its nature presently. First let us
see how these primitive types of plants come to form the immense
forests which are recorded in our coal-beds. Dr. Russel Wallace
has lately represented these forests, which have, we shall see,
had a most important influence on the development of life, as
somewhat mysterious in their origin. If, however, we again
consult the geologist as to the changes which were taking place
in the distribution of land and water, we find a quite natural
explanation. Indeed, there are now distinguished geologists (e.g.
Professor Chamberlin) who doubt if the Coal-forests were so
exceptionally luxuriant as is generally believed. They think that
the vegetation may not have been more dense than in some other
ages, but that there may have been exceptionally good conditions
for preserving the dead trees. We shall see that there were; but,
on the whole, it seems probable that during some hundreds of
thousands of years remarkably dense forests covered enormous
stretches of the earth's surface, from the Arctic to the
Antarctic.
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