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

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EARTH'S SHIFTING CRUST
On the other hand, a shifting of the masses of lighter rock,
which might have formed the downward projections of con-
tinents and mountain chains, as the result of a displacement,
could lighten certain sectors of the crust and result in their
uplift.
That rocks of light weight are to be found at the very
bottom of the crust (and even in the downward projections
under continents and mountain chains that extend to greater
depth) might, as a matter of fact, have been deduced from
Daly's observation that the process of mountain folding has
involved the whole depth of the crust, and not just its surface
layers (97:399)- His suggestion is that since the folding of
the crust to form mountain ranges involves its horizontal
shortening, the horizontal shearing movement has to take
place at the level where displacement will be easiest, which
will be at the bottom of the crust where the rock has mini-
that at a level at which
mum, or zero, strength. For it is plain
the rock possessed any considerable tensile strength, the
shearing of one layer over another horizontally would be
practically out of the question.
It would seem, from these considerations, that the com-
monly used terms "sial" and "sima" to differentiate lighter
from heavier material in the crust, especially when they are
presumed to indicate different layers, have very little meaning.
They amount to trends merely, and take no account of
the detailed distributions of the materials of different density
either vertically or horizontally. It would be wrong, therefore,
to assume that just because we find a layer of basalt on
the floor of the Atlantic (as has been recently reported) this
layer necessarily extends to the bottom of the crust, and is
not underlain, at greater depth, by sedimentary and granitic
rocks of less density. It is even true that the layer of basalt
may have been extruded during
the subsidence of the sea
bottom in the last movement of the crust, and have been,
in itself, one cause of the subsidence.
Jaggar, for one, considered that it was far more reasonable
to account for subsidence or elevation at the surface by