le of land and sea brought over the face of the earth.

As we have no recognisable remains of the animals and plants of the
earliest age, we will not linger over the Archaean rocks. Starting from
deep and obscure masses of volcanic matter, the geologist, as he
travels up the series of Archaean rocks, can trace only a dim and
most unsatisfactory picture of those remote times. Between outpours of
volcanic floods he finds, after a time, traces that an ocean and rivers
are wearing away the land. He finds seams of carbon among the rocks of
the second division of the Archaean (the Keewatin), and deduces from
this that a dense sea-weed population already covered the floor of
the ocean. In the next division (the Huronian) he finds the traces of
extensive ice-action strangely lying between masses of volcanic rock,
and sees that thousands of square miles of eastern North America were
then covered with an ice-sheet. Then fresh floods of molten matter are
poured out from the depths below; then the sea floods the land for a
time; and at last it makes its final emergence as the first definitive
part of the North American continent, to enlarge, by successive fringes,
to the continent of to-day. [*]

* I am quoting Professor Coleman's summary of Archaean
research in North America (Address to the Geological Section
of the British Association, 1909). Europe, as a continent,
has had more "ups and downs" than America in the course of
geological time.

This meagre picture of the battle of land and sea, with interludes of
great volcanic activity and even of an ice age, represents nearly all
we know of the first half of the world's story from geology. It is
especially disappointing in regard to the living population. The very
few fossils we find in the upper Archaean rocks are so similar to those
we shall discuss in the next chapter that we may disregard them, and the
seams of carbon-shales, iron-ore, and limestone, suggest only, at the
most, that life was already abundant. We must turn elsewhere for some
information on the origin and early development of life.

The question of the origin of life I will dismiss with a brief account
of the various speculations of recent students of science. Broadly
speaking, their views fall into three classes. Some think that the germs
of life may have come to the earth from some other body in the universe;
some think that life was evolved out of non-living matter in the early
a