Corals and coral islands.

248

FORIMATYION OF CORAL REEFS AND ISLANDS.

e. The following figure of the harbor of Falita, Upolu,
represents another coral harbor, as surveyed by Lieutenant
Emmons. At its head there is a stream twenty-five or thirty
yards wide and three feet deep. Notwithstanding the unusual
size of the river, the coral reef lies near its mouth, and proHARBOIt OF FALIFA.
jects some distance in front of it. Its surface is dead, but
corals are growing upon its outer slope.
j: The harbor of Rewa, in the Feejees, may be again alluded to. The waters received by the bay amount to at least
500,000 cubic feet a minute. Yet there is an extensive reef
enclosing the bay, lying but three miles from the shores, and
with only two narrow openings for ships. The case is so remarkable that we can hardly account for the facts without
supposing the river's mouth to have neared the reef by depositions of detritus since the inner parts of the reef were formed;
and there is some evidence that this was the case, though to
what distance we cannot definitely state. With this admission, the facts may still surprise us; yet they are explained on
the principle that fresh water does not sink in the ocean, but
is superficial, and runs on in a distinct channel; its effect is almost wholly through hydrostatic pressure, increasing the force
of the underwater currents, and through their depositions of
detritus Besides these instances, there are many others in
the Feejees, as will be observed on the chart at the end of
this volume. Mokungai has a large harbor, without a
stream of fresh water;-so also Vakea and Direction Island.