Couthouy, one of
the naturalists in the great Antarctic Expedition of the United
States:--"Having personally examined a large number of
coral-islands, and resided eight months among the volcanic class
having shore and partially encircling reefs, I may be permitted to
state that my own observations have impressed a conviction of the
correctness of the theory of Mr. Darwin." The naturalists, however,
of this expedition differ with me on some points respecting coral
formations.)
(PLATE 98. BOLABOLA ISLAND.)
It may be asked whether I can offer any direct evidence of the
subsidence of barrier-reefs or atolls; but it must be borne in mind
how difficult it must ever be to detect a movement, the tendency of
which is to hide under water the part affected. Nevertheless, at
Keeling atoll I observed on all sides of the lagoon old cocoa-nut
trees undermined and falling; and in one place the foundation-posts
of a shed, which the inhabitants asserted had stood seven years
before just above high-water mark, but now was daily washed by
every tide; on inquiry I found that three earthquakes, one of them
severe, had been felt here during the last ten years. At Vanikoro
the lagoon-channel is remarkably deep, scarcely any alluvial soil
has accumulated at the foot of the lofty included mountains, and
remarkably few islets have been formed by the heaping of fragments
and sand on the wall-like barrier reef; these facts, and some
analogous ones, led me to believe that this island must lately have
subsided and the reef grown upwards: here again earthquakes are
frequent and very severe.
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