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

CAMPBELL'S MECHANISM 373
surface. A high plateau may represent an area of deficient
mass, and an ocean basin may represent an area of excess
mass. We have seen that there are many oceanic areas that
show positive isostatic anomalies, or the existence of local
excesses of mass in the earth's crust. We can easily see the
distinction between the level equipotential surface of the
geoid, represented by sea level, and the surface of mass that
may deviate considerably from the level surface.
The mechanism for crust displacement presented in this
book depends upon recognition of the fact that distortions of
mass on the earth's surface, of whatever if
type, they consti-
tute anomalous additions of mass at points on the earth's
surface, will give rise to centrifugal effects like the effect of
the mass attached to the surface of Brown's rotating model
sphere, in accordance with ordinary principles of mechanics,
and measurable by the standard formula for calculating
centrifugal effects.
An example may serve to illustrate the difference between
the surface of mass, which differs in elevation from place to
place, and the equipotential, geoidal surface. Let us take a
fictional case of a mass out of isostatic adjustment but with
its center of gravity below the surface of the geoid. Let us
that under the bottom of the Atlantic Ocean we
suppose
have a slab of material ten times as dense as basalt, two thou-
sand miles long, one thousand miles wide, and forty miles
thick. The excess of mass in this slab, as compared with other
sectors of the crust, would be enormous, and gravity would
be greater at the surface. Consequently, the ocean level over
this area would be affected slightly, but the shape of the geoid
would not be significantly changed, and the sea level would
still represent an equipotential surface. The center of grav-
ity of the anomalous mass of high density would be depressed
far below sea level; it might be fifteen or twenty miles below
the geoidal surface. Now if the slab were of average density,
the depression of the center of gravity would mean an in-
verse Eotvos effect, that is, a poleward centrifugal effect, the
quantity of which, as we have seen, would be slight. But, now,