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

THE MOUNTAINS 12Q
plete. It has been estimated that if all the sedimentary beds
of all geological periods were added together (that is, the en-
tire amount of sediment that has been weathered out of the
mountains and continents and accumulated to make sedi-
mentary rocks since the beginning of geological time), the
total thickness of sediment would be about eighty miles. At
the present time, however, the average thickness of the sedi-
of the earth's crust is esti-
mentary rocks of the upper part
mated to be no more than a mile and a half (333). What has
happened to all the missing sediment? The answer is that it
has been used over again. At the present time, all over the
earth, the forces of the weather and the sea are busy wearing
away or grinding up rock, and most of the rock they are
destroying is sedimentary rock. Thus more than 95 per cent
of all the sedimentary rocks formed since the beginning of
the planet has been destroyed. As a result of this, geologists
have been forced to piece together this geological record
from widely separated beds. They find a part of the Silurian
sediment in the United States, and another part in Africa,
and so on.
The enormous difficulty of piecing together the geological
record from these discontinuous and scattered beds is ren-
dered even greater by the fact that vast areas of what were
once lands are now under the shallow epicontinental seas,
and even under the deep sea (as we shall see in the next
chapter). Let us remember, too, that even among
the still-
existing beds now to be found on the lands, only a tiny
percentage are at or near the surface and thus available for
study. And of these a large proportion are in such remote
and geologically unexplored areas as Mexico, the Amazon,
and Central Asia. And still, despite these enormous handicaps,
new periods of mountain formation are constantly being
discovered. Umbgrove remarks that a long list of them
has been "gradually disclosed to us" (430:27).
It seems to me
that there is unjustifiable complacency in the assumption
that the list of mountain-forming epochs is now complete.