408 Life and Immortality. 
conditions that are essential to the life of the species or con- 
ducive to its extension. But notwithstanding the difficulties 
in the way, we are able in many cases to deduce completely 
trustworthy conclusions concerning the climate of a given 
geological period by an examination of its fossil remains. 
In Eocene times, or at the beginning of the Tertiary Period, 
the climate of what is now Western Europe was of a tropical 
or sub-tropical character, the Eocene beds being found to 
contain the remains of cowries and volutes, such shells as 
now inhabit tropical seas, together with the fruits of palms 
and remains of other tropical plants. And further, it has 
been shown that in Miocene times, or about the middle of 
the same epoch, the central parts of Europe were peopled 
with a luxuriant flora resembling that of the warmer parts 
of the United States, and that Greenland, now buried for the 
most part beneath a vast ice-shroud, was warm enough to 
support a large number of trees, shrubs and other plants 
that are at present denizens of the temperate regions of the 
globe. 
And lastly, from the study of fossils, geologists first learned 
to comprehend a fact, that is, that the crust of the earth is 
liable to local elevations and subsidences, which may be 
regarded as of cardinal importance in all modern geological 
theories and speculations. Long after the remains of shells 
and those of other marine animals were first observed in the 
solid rocks constituting the dry land, and at great elevations 
above the sea-level, attempts were made to explain this 
unintelligible phenomenon upon the hypothesis that these 
remains or fossils were mere /usus nature, due to some 
“plastic virtue latent in the earth.” But the common-sense 
of science soon rejected this idea, and it was universally 
agreed that these bodies were really the relics of animals 
that once lived in the sea. When once this was admitted, 
further steps in the right way of thinking became compara- 
tively easy, and at the present day no geological doctrine 
stands on a surer foundation than that which teaches that 
