Thus the Radack group of atolls is an irregular
square, 520 miles long and 240 broad; the Low Archipelago is
elliptic-formed, 840 miles in its longer, and 420 in its shorter
axis: there are other small groups and single low islands between
these two archipelagoes, making a linear space of ocean actually
more than 4000 miles in length, in which not one single island
rises above the specified height. Again, in the Indian Ocean there
is a space of ocean 1500 miles in length, including three
archipelagoes, in which every island is low and of coral formation.
From the fact of the reef-building corals not living at great
depths, it is absolutely certain that throughout these vast areas,
wherever there is now an atoll, a foundation must have originally
existed within a depth of from 20 to 30 fathoms from the surface.
It is improbable in the highest degree that broad, lofty, isolated,
steep-sided banks of sediment, arranged in groups and lines
hundreds of leagues in length, could have been deposited in the
central and profoundest parts of the Pacific and Indian Oceans, at
an immense distance from any continent, and where the water is
perfectly limpid. It is equally improbable that the elevatory
forces should have uplifted throughout the above vast areas,
innumerable great rocky banks within 20 to 30 fathoms, or 120 to
180 feet, of the surface of the sea, and not one single point above
that level; for where on the whole face of the globe can we find a
single chain of mountains, even a few hundred miles in length, with
their many summits rising within a few feet of a given level, and
not one pinnacle above it? If then the foundations, whence the
atoll-building corals sprang, were not formed of sediment, and if
they were not lifted up to the required level, they must of
necessity have subsided into it; and this at once solves the
difficulty.
Pages:
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904