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best characterized of these, namely, the Maldive islands, extend
in length for 480 miles, with an average breadth of si.xty.
These atolls agree in most respects with the lagoons of the
Pacific; they differ, however, in several of them being
crowded together—such little groups being separated from
other groups by profoundly deep channels. Now if we look
ill a chart, at the prolongation of the reef towards the northern
end of New Caledonia, and then complete the work of subsidence,
so as to continue producing the same results; we
should have the original reef broken up into many patches;
each of which, from the vigorous growth of coral on the outside,
would have a constant tendency to assume a rounded
form. Every accidental break in the continuity of the first
line would determine a fresh circle. In the case, therefore,
of the Low or Dangerous Archipelago in the Pacific, I believe
that the lagoon islands were moulded round the flanks of so
many distinct islands; but in the Maldives, that one single
mountainous island, bordered by reefs, and very nearly of the
same actual figure and dimensions with New Caledonia, formerly
occupied that part of the ocean.
Lastly, to the extreme westward, the coast of Africa is
closely skirted by coral reefs, and according to facts stated in
Captain Owen’s voyage, has probably been uplifted within a
recent period. The same remark applies to the northern
part of Madagascar, and, judging from the reefs likewise at
the Seychelles, situated on the submarine prolongation of
that gi-eat island. Between these two, N.N.E. and S.S.W.
lines of elevation, some lagoon and widely-encircled islands
indicate a band of subsidence.
When we consider the absence both of widely-encircling
reefs and lagoon islands in the several archipelagoes and
wide areas, where there are proofs of elevations; and on the
other hand the converse case of the absence of such proof
where reefs of those classes do occur; together with the juxtaposition
of the different kinds produced hy movements of
the same order, and the symmetry of the whole, I think it
will be difficult (even independently of the explanation it
Aprii, 1836. C O R A L F O BMA T i O N S ,
offers of the peculiar configuration of each class) to deny
a great probability to this theory. Its importance, if true, is
evident; because we get at one glance an insight into the
system by which the surface of the land has been broken up,
in a manner somewhat similar, but certainly far less perfect,
to what a geologist would have done who had lived his ten
thousand years, and kept a record of the passing changes.
We see the law almost established, that linear areas of great
extent undergo movements of an astonishing uniformity, and
that the bands of elevation and subsidence alternate. Such
phenomena at once impress the mind with the idea of a fluid
most gradually propelled onwards, from beneath one part of
the solid crust to another.
1 cannot at present do more than allude to some of the
results which may be deduced from these views. If we
examine the points of eruption over the Pacific and Indian
oceans, we shall find that all the active volcanoes occur
within the areas o f elevation. (The Asiatic band must be
excepted; inasmuch as we are entirely in want of information
of all kinds respecting it.) On the other hand, in the great
spaces supposed to be now subsiding, between the Radack
and Dangerous Archipelagoes, in the Corallian sea, aud among
the atoUs which front the west coast of India, not one occurs.
If we look at the changes of level as a consequence of the
propulsion of fluid matter beneath the crust, as before suggested,
then the area to which the force is directed might be
expected to yield more readily than that whence it was gradually
retiring. I am the more convinced that the above law
is true, because, if we look to other parts of the world, proofs
of recent elevation almost invariably occur, where there ar.e
active vents: I may instance the West Indies, the Cape de
Verds, Canary Islands, southern Italy, Sicily, and other
places. But in answer to this, those geologists, who, judging
from the history of the isolated volcanic mounds of Europe,
were inclined to believe that the level of the ground was constantly
oscillating up and down, might maintain that on these
same areas, the amount of subsidence had been equal to that
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