"geosyncline," a vast trough, or cradle, being slowly filled with
sediment brought down by the rivers from the adjoining shores. These
sediments accumulate to the enormous depth of twenty-five thousand
feet, and harden into rock. Then in the course of time they are
squeezed together and forced up by the contraction of the earth's
crust, and thus the Appalachians are born. When Mother Earth takes a
new hitch in her belt, her rocky garment takes on new wrinkles. Just
why the earth's crust should wrinkle along lines of rock of such
enormous thickness is not a little puzzling. But we are told it is
because this heavy mass of sediment presses the sea-bottom down till
the rocks are fused by the internal heat of the earth and thus a
line of weakness is established. In any case the earth's forces act
as a whole, and the earth's crust at the thickest points is so
comparatively thin--probably not much more than a heavy sheet of
cardboard over a six-inch globe--that these forces seem to go their
own way regardless of such minor differences.

The Alps and the Himalayas, much younger than our Appalachians, were
also begotten and nursed in the cradle of a vast geosyncline in the
Tertiary seas. We speak of the birth of a mountain-range in terms of
a common human occurrence, or as if it were an event that might be
witnessed, measurable in human years or days, whereas it is an event
measurable only in geologic periods, and geologic periods are marked
off only on the dial-face of eternity. The old Hebrew writer gave
but a faint image of it when he said that with the Lord a thousand
years are as one day; it is hardly one hour of the slow beat of that
clock whose hours mark the periods of the earth's development.

The whole long period during which the race of man has been rushing
about, tickling and scratching and gashing the surface of the globe,