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

178
EARTH'S SHIFTING CRUST
Now, as I understand Professor Bain's statement, his point
is that in numerous instances erosion has worn away moun-
tain ranges, leaving flat plains (peneplains), and in the in-
stance he cites it seems that during the prolonged period
when the erosion was taking place (erosion that resulted in
removal of no less than 10,000 feet of rock from one area, and
the deposition of the resulting sediments in another), the
crust did not respond by rising in the first area and sinking
in the second. Gravitational balance was thus sadly set askew,
and remained so for a long time. Then, relatively suddenly,
equilibrium was re-established. How do we explain this?
I think it is necessary to take into consideration the fact
that just as compression will be at a maximum along the
meridian of displacement of the crust in the poleward direction,
extension or stretching will likewise be at a maximum
along the same meridian in the equatorward direction. But,
in both cases, areas removed from this meridian will be dis-
placed proportionately less, and large areas will undergo very
little or no displacement, and consequently very little or no
compression or extension. Since, as we saw in the last chapter,
successive movements of the crust may oscillate along merid-
ians placed close together, it follows that, for long periods,
compression may be sustained in particular areas and isostatic
adjustment impeded in those areas. Eventually, a movement
of the crust in a different direction will permit the delayed
adjustment to take place.
In this way, too, we may explain the data upon which Dr.
Jeffreys based his conclusion that isostasy is an exceptional
condition of the earth's surface, which is re-established only
at long intervals. The theory presented in this book offers a
solution for the cause of the geological revolutions which,
he supposed, shattered the crust at long intervals, bringing
about the formation of mountains, and permitting the re-
establishment of crustal balance.
With regard to the vast negative or positive distortions of
isostasy, the displacement theory has a solution to offer. Let
us suppose a movement of the crust causing widespread slight