On The
Other Hand, Although Most Of The Islands In The Pacific Which
Are Encircled By Barrier-Reefs, Are Of Volcanic Origin, Often
With The Remnants Of Craters Still Distinguishable, Not One Of
Them Is Known To Have Ever Been In Eruption.
Hence in these
cases it would appear, that volcanos burst forth into action
and become extinguished on the same spots, accordingly as
elevatory or subsiding movements prevail there.
Numberless
facts could be adduced to prove that upraised organic remains
are common wherever there are active volcanos; but until it
could be shown that in areas of subsidence, volcanos were
either absent or inactive, the inference, however probable in
itself, that their distribution depended on the rising or
falling of the earth's surface, would have been hazardous. But
now, I think, we may freely admit this important deduction.
Taking a final view of the map, and bearing in mind the
statements made with respect to the upraised organic remains,
we must feel astonished at the vastness of the areas, which
have suffered changes in level either downwards or upwards,
within a period not geologically remote. It would appear
also, that the elevatory and subsiding movements follow
nearly the same laws. Throughout the spaces interspersed
with atolls, where not a single peak of high land has been
left above the level of the sea, the sinking must have been
immense in amount. The sinking, moreover, whether continuous,
or recurrent with intervals sufficiently long for the
corals again to bring up their living edifices to the surface,
must necessarily have been extremely slow.
Enter page number
PreviousNext
Page 737 of 776
Words from 197588 to 197849
of 208183
