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

110 EARTH S SHIFTING CRUST
What could be the cause of such a pulling apart of the
crust? Surely not a shrinking and cooling of the earth. It is
also very unlikely, it will be admitted, that the earth could
be growing fast enough to produce this split and the accom-
panying geological instability. On the other hand, a displacement
of the crust, or rather a series of them, may explain the
facts. It even appears that here, in this system of profound
cracks in the crust, we have evidence of the existence of zones
of crustal weakness along which, perhaps time and again, the
splits have occurred that have permitted the displacement of
the crust, and at the same time have relieved some of the
resulting tension and thereby limited the tectonic consequences
of the displacements so far as other areas of the
earth's surface are concerned.
To return briefly to the question of block mountains, Mr.
Campbell has a further suggestion as to the way in which
compression in a poleward displacement, and subsequent
fracturing, may combine to cause them. One of the problems
that awaits solution in geology is the cause of the widespread
doming and basining of the crust that occurs from place to
place. The domes are sometimes of considerable extent. Ex-
amples of basins include the Gulf of Mexico and the Caspian
and Black Seas. Campbell points out that if an area is dis-
placed poleward, and is thereby subjected to four compres-
sions, as already mentioned, limited areas will be entrapped
by these compressions, and doming must result; conversely,
in areas moved equatorward the reverse must occur, and
larger or smaller basins will tend to be produced.
A block mountain might tend to be produced, Mr. Campbell
thinks, if a major fault should bisect a domed-up area.
This would create the possibility that the abutting rock sec-
tions of one half of the dome might give way, allowing half
the dome to collapse, and pushing subcrustal viscous or plas-
tic rock under the other half of the dome, thus rendering
the latter permanent. This effect, however, would depend
upon many
local circumstances.