No trace will ever be found in the rocks of the first few
million years in the calendar of life.
The word impossible or unknowable is not lightly uttered in
science to-day, but there is a very plain reason for admitting it
here. The earliest living things were at least as primitive of
nature as the lowest animals and plants we know to-day, and
these, up to a fair level of organisation, are so soft of texture
that, when they die, they leave no remains which may one day be
turned into fossils. Some of them, indeed, form tiny shells of
flint or lime, or, like the corals, make for themselves a solid
bed; but this is a relatively late and higher stage of
development. Many thousands of species of animals and plants lie
below that level. We are therefore forced to conclude, from the
aspect of living nature to-day, that for ages the early organisms
had no hard and preservable parts. In thus declaring the
impotence of geology, however, we are at the same time
introducing another science, biology, which can throw appreciable
light on the evolution of life. Let us first see what geology
tells us about the infancy of the earth.
The distribution of the early rocks suggests that there was
comparatively little dry land showing above the surface of the
Archaean ocean.
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