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

190
EARTH'S SHIFTING CRUST
ago, which are still suggestive of the probable
material in the asthenosphere:
behavior of
The ingenious experiments of M. Tresca on the flow of solids
have thrown considerable light on the internal deformations of rock-
masses. He has proved that, even at ordinary atmospheric temperatures,
solid resisting bodies like lead, cast iron, and ice may be so
compressed as to undergo an internal motion of their parts, closely
analogous to that of fluids. Thus a solid jet of lead has been produced,
by placing a piece of the metal between the jaws of a powerful
compressing machine. Iron, in like manner, has been forced to
flow in the solid state into cavities and take their shape. On cutting
sections of the metal so compressed, their particles of crystals are
found to have arranged themselves in lines of flow which follow
the contours of the space into which they have been squeezed. . . .
(170:316).
It seems altogether unlikely that material under the pres-
sures prevailing at the bottom of the crust, and at very high
temperatures, could resist the shearing movement of the crust
over it. Let us remember that in a displacement of the crust
very little material, comparatively speaking, would actually
have to flow. The crust would simply start to slip over the
the most
asthenosphere. The action would be one of gliding,
economical form of motion, though, as already explained,
the downward protuberances of continents and mountain
chains might act to slow down the movement.
To conclude, then, the asthenosphere could have consid-
erable viscosity, even at the top, and yet offer no definite
obstacle to the displacement of the crust. Once the crust
started to move, the braking influence of the viscosity would
steadily decline, for with the increasing distance of the cen-
ter of mass of the icecap from the axis, the centrifugal effect
would be multiplied (Chapter XII). No friction between the
two layers could suffice to absorb this ever increasing thrust.
It would have to continue until the motive force was removed
by the melting of the icecap in the warmer latitudes.
And, in the meantime, as Frankland has suggested, the fric-
tion would have been productive of heat that might have
further facilitated the movement.