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

CONTINENTS AND OCEAN BASINS 153
changes of weighting deep in the crust than by erosion and
sedimentation at the surface. He remarked:
... It would seem possible that intrusive and extrusive processes
may lighten or weight the crust much more profoundly than the
movement of sediments (235: 153).
How, precisely, would these processes be apt
to be set in
motion by a displacement of the crust? We saw that a dis-
placement would cause a general fracturing of the crust, the
creation of a new world-wide fracture pattern. In areas moved
toward the equator, the extension of the surface area would
involve some pulling apart of the crust, the separation of the
fragments, their subsidence into the semiliquid melt below,
and the rise of the magma into the fractures, with, at some
points no doubt, massive eruptions on the surface. Differen-
tial movements of blocks of the crust would occur as each
sought its gravitational equilibrium, some rising and others
subsiding. In areas moved poleward compression would be
the rule, with some folding of the crust, with block faulting
accompanied by tilting of larger or smaller blocks. In these
areas the strata of lighter rock would grow thicker, from
being folded upon themselves; in equatorward-moving areas,
on the other hand, they would tend to grow thinner, because
much of the lighter rock might be engulfed in the rising
heavy magma.
However, major changes
in the situation of continents
require additional processes, even though changes
such as
those suggested above might, if they accumulated over long
results. The massive
periods of time, produce very important
changes, capable of subsiding or elevating continents, might
be of two different sorts, though both of them must, in the
nature of things, remain speculative for the present. One of
these would be the massive intrusion of immense quantities
of heavy magma into the crust
(resulting finally in plateau
basalts). Such an effect could be produced by subcrustal currents
set in motion by a displacement, and would have the
effect of causing a major subsidence at the surface. The other
cause of massive change in the average density of a given col-