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

THE SHAPE OF THE EARTH 163
ment within the rigid crust itself. They remark: ". . . it
for the strains due to the re-
requires several thousand years
moval of the ice load to be reduced to half" (195:101). This
and the preceding statements may serve to establish the rea-
sonable presumption that any icecap, at the height of its
rapid accumulation, must be largely uncompensated.
But even if, during the rapid growth of the present An-
tarctic icecap, a degree of isostatic adjustment has taken
place, this does not end the matter for us. We must ask,
Where does this plastic rock go? Presumably it flows out,
under the crust below the ocean bed, beyond the fringes of
the ice-covered continent, at a depth of twenty to forty miles
below the surface of the earth. It may raise the crust somewhat
for a distance beyond the edges of the ice sheet. Dr.
Harold Jeffreys gave it as his opinion that, if a gravity survey
of Antarctica should be undertaken, we might expect to
find marked positive anomalies around the coasts (241). But,
since in general the plastic rock under the crust is not flowing
into any area of deficient mass, the flow, upraising the coasts
or the sea bottoms off the coasts, must still constitute excess
matter, and must exert a centrifugal effect about equal to
the former effect of the ice that has now been brought into
equilibrium.
Let us consider this point a little further. We have noted,
above, that according to the definition of isostasy, the process
is a response to the transfer of material from one region to
another: sediment is removed from an area of "denudation"
and transferred to an area of "deposition." The area of deposition,
then, sinks under the load, and a flow of rock under
the crust moves back to the area of denudation, compen-
sating for the material that has been removed, and restoring
the equilibrium. But where can the plastic rock displaced
by the icecap flow? No adjacent area ha$ been lightened by
the removal of sediment; the plastic rocK must, then, wherever
it flows, create a distortion, a surplus of matter, which
will have a centrifugal effect.
From the standpoint of the theory presented in this book,