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

332
EARTH'S SHIFTING CRUST
Umbgrove mentions two specific examples of this phenomenon:
The most important point of all, as far as we are concerned, is
that the two major periods of strong differentiation of plant life
correspond with two major periods of mountain-building and glaciation
of the Upper Paleozoic and Pleistocene (429:292).
The same thing is described by Professor Erling Dorf, of
Princeton (349:575-91). We need not take too seriously the
small number of turning points mentioned by them for the
reason that everything, after all, is relative. The turning
points mentioned by Umbgrove might turn out to have been,
in some respects, the most important turning points in the
history of life, and yet there may have been a hundred lesser,
but still very important, turning points.
Geologists who have sought an explanation of the rela-
tionship between biological and geological change have, in
some cases, favored the idea that geological change, such as
the formation of new mountain ranges, might have caused
both ice ages and biological change. We have seen that this
will not account for ice ages. We have also seen that geologists
now generally admit their failure to explain mountain
building. It is unsatisfactory to attempt to explain the known
by the unknown; it will not do to drag in mountain build-
ing as the cause of evolution, when the former also is
unexplained.
Displacements of the earth's crust appear
to be the con-
necting link between these different processes: they explain,
at one and the same time, ice ages, mountain formation, and
the significant turning points of evolution.
6. The Extinction of Species
It has already been shown (Chapter VIII) that our theory can
provide an explanation for the extinction of species. Some
further discussion of this problem is, however, required.
It has been suggested that the history of any particular