God Arises
The Challenge of The Qur’an
~ 365 ~
constituents and elevations of their upper surfaces
are significantly different. This means that an excess
of mass seen as material above sea level, as in a
mountain system, is due to a deficit of mass, or low-
density roots, below sea level.
“In the theory of isostasy a mass above sea level is
supported below sea level, and thus there is a
certain depth at which the total weight per unit area
is equal all around the world; this is known as the
depth of compensation” (V/458).
The apparent unchangeability of the mountains—
the ‘immovable mountains’ of the Quran—is
explained by the
Encyclopaedia Britannica
(1984) in
terms of this naturally occurring balance:
“Most of the Earth’s crust is approximately in
hydrostatic equilibrium in this way, so that
when erosion occurs and rivers transport
large quantities of weathered material away
from the upland areas to be deposited in the
oceans, there is a tendency for the hinterland
to rise isostatically, and for the adjacent ocean
floor to sink” (6/44).
