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

THE SHAPE OF THE EARTH 1Q1
I have not referred to another important aspect of the be-
havior of materials under pressure, one that may
have its
importance. If the viscosity of matter increases with pressure,
so does plasticity. Solids become more and more plastic under
pressure. At the bottom of the crust matter is under enormous
pressure. That means that very little force may be required
to overcome its rigidity. It also means that when a
critical point is reached, the material may deform suddenly.
It does not give way at a speed proportional to the pressure
applied, as khthe case of a viscous liquid, but at a speed that
has no relationship to the applied force. Bridgman has
pointed out that the exact degree of plasticity
at the bottom
of the crust, like that of the viscosity, cannot be determined
because of our ignorance of the chemical composition of the
materials.
This question of plastic deformation raises an interesting
possibility. What if, at a certain point in the displacement,
viscous deformation gives way to plastic deformation? Suppose
the movement starts slowly as a gliding over a viscous
surface. it Suppose gains enough speed so that, at the inter-
face between the crust and the underlying plastic layer, a
plastic type of yielding occurs. The interactions here would
be complex, but the possibility looms that at times the dis-
placement of the crust could take place
speed.
with considerable
I have mentioned that the gliding motion of the crust
might be impeded at times by the downward projections of
its undersurface. However, if there is one situation in which
plastic deformation might be considered probable, it is one
in which these downward projections for example, the un-
derbody of a continent were displaced against upward projections
of the asthenosphere under the ocean basins. Here
considerable pressures would arise, and various circumstances
might concentrate these pressures in narrow regions and in-
tensify them; the pressures might thus reach the critical
point of plastic deformation, and result in the abrupt shear-
ing off of larger or smaller segments of the downward pro-