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

374
EARTH'S SHIFTING CRUST
to counteract this, the rotation of the earth, acting on this
mass of ten times normal density, would produce a centrifugal
effect ten times as great as the one normally balanced at
that point by the effects of gravity. Let us note the fact that
the assumption that this slab is not isostatically compensated
involves the consequence that the centrifugal momentum
resulting from it is not compensated.
The difference between an Eotvos effect and one produced
by an uncompensated mass may be illustrated in another
way. Let us return to our example of a mass of ice. Campbell
has suggested the example of an iceberg before and after its
separation from its parent, land-based icecap. It is assumed
that the is icecap uncompensated. The iceberg, breaking off
from the icecap, falls into the water. Before this event the
surface of
icecap, by assumption, is outside the equilibrium
the geoid; the rotation of the earth acts it upon precisely as
the rotation of Brown's model sphere acts upon the weight
fixed to its surface.
But let us see what happens when the iceberg falls into
the sea. It now reaches gravitational equilibrium. It sinks,
and displaces its weight in water. It is now a part of the equi-
potential surface of the geoid (though the portion projecting
above sea level is not, and therefore exerts an Eotvos effect).
Now what is the quantitative relationship between the
Eotvos effect and the original centrifugal effect of the ice-
berg? It is plain
that now nine tenths of the ice is within
the equilibrium surface. For this nine tenths of the mass the
equatorward centrifugal momentum produced by the earth's
rotation is precisely cancelled by the poleward component of
the force of gravity at that point, so that there is no net centrifugal
effect. Only one tenth of the ice remains to exert an
effect, and the quantity of this effect, furthermore, is determined
by the elevation of the center of gravity of this
tenth of the iceberg above sea level. But the elevation has
been enormously reduced. It has, in fact, been reduced to one
tenth of the elevation of the center of gravity before the fall
of the iceberg into the sea. Campbell has pointed out that,