The Earth's Shifting Crust by Charles Hapgood - wire of information

2o8 EARTH'S SHIFTING CRUST
It will remain until, in the course of time, it is absorbed
by the vegetation, or by chemical processes in the rock surfaces
exposed to the weather. Therefore, as compared with
volcanic dust, carbon dioxide is a long-range factor, and its
effect is opposite to that of the dust.
In any displacement of the crust it follows that massive
outbursts of volcanism must have added to the supply of
carbon dioxide in the air. Its proportion in the atmosphere
must have finally been raised far above normal. In conse-
quence, it is likely that whenever volcanic activity declined
sufficiently to permit a warming of the climate, the high
proportion of carbon dioxide in the air may have acted to
intensify the upward swing of the temperature. This would
have increased the violence of the oscillations of the climate,
and would have accelerated many geological processes.
Evidence that the proportion of carbon dioxide in the air
was, in fact, higher toward the end of the ice age than it is
now is provided by recent studies of gases contained in ice-
bergs. Scholander and Kanwisher, writing in Science, re-
ported that air frozen into these bergs, presumably dating
from the ice age, showed lower oxygen content than air has
at the present time, and theorized:
Possibly this ice was formed as far back as Pleistocene time, when
cold climates may have curbed the photosynthetic activity of green
plants over large parts of the earth, resulting in a slight lowering
of the oxygen content of the air (368:104-05).
The weight of a great deal of evidence presented in this
book is opposed to this particular speculation; we must suppose,
on the contrary, that the earth's surface as a whole was
then no colder than it is now, and that just as many plants
were absorbing carbon dioxide and releasing oxygen into
the air then as now. But the same fact the lower proportion
of oxygen may perhaps be explained by supposing a higher
proportion of carbon dioxide, especially if we assume a mas-
sive increase in the proportion of that gas in the air.
Another consideration that greatly strengthens this line of