Polynesian., 1844-06-08
BY a recent decree of Peru, whalers are
forbidden to touch at Pisco.
Literary Notices.

Wth ouggeStfOnS as 10 me causes OF Mear
Absence in the same parallels of latitude on
the Coast Of South .americe. BY JOSEPH
P. CoUTHouY. Boston, 1842.
Continued from our last.)
1t has been a common beliefthat the growth
of coral was very rapid, and that the coral
insects were silently but speedily not only
giving birth to new reefs, islands, but even
continents were destined by their labors to
rise above the waters. Later observations
have disproved this theory, and it has been
ascertained that the increase of coral is ex-
ceeding slow. Probably the growth of coral
operates in the sea in the same manner, and
with proportionate effect to the growth of
vegetation ashore. In fact coral, so far from
creating reefs from the illimitable depths of
the ocean, requires a permanent foundation
for its own eXistence-and obeys the laws of
temperature and density of sea-pressure as
regularly as vegetation on shore the changes
of atmosphere. Mr.. G. devotes many pa
ges to accounting for the multifarious forms
of coral islands, lagoons, reefs, SC; their
gradual changes, growth of vegetation upon
them, etc. The result of his observations on
reef-growing coral is as follows. 1t grows
most compactly and vigorously at a depth of
from three to eight fathoms, though found
not unirequently at a much greater depth
even at twenty fathoms. He says
"It is my belief that, to a certain extent. the CO.
rails are limited i'm their range of prOvth nv temnaro-
ture rather than depth, and that wherever this is not
below TO- Fair. there, cGteris paribuS, they will be
found to flourish, as in the Polynesian seas; accord
ingly we find that their principal formations are
placed within the tropics, and though | have no
means of ascertaining at this moment the fact, | APP
prehend that in the Indian Ocean, as in the Pacific,
the saxigenous polypes will be found most abundant
and at their greatest depths, in a belt comprising
about twenty degrees on each side of the equator.
But even allowing that they invariably commen-
ced their structures at the extreme depth of twenty
fathoms, it is obvious that no reef would attain a
thickness of much more than a hundred feet, before
the labors of the polypes must cease and themselves
perish, in consequence of their exposure to the suns
rays. The question then naturally arises, how are
we to account for the existence of coral banks, so
greatly exceeding this thickness as some are known
to do; if it is thus %disproved that their p~olypes build
at corresponding depths?
Mr.. Chas. Darwin, who accompanied King and Fitz-
roy, as Naturalist, in their late survey of the east
cIu CAIICiiity Vi our COHtIncIll,W was 4 DV MS eXanl-
nation of a lagoon island, (the only one | be-
lieve on which he landed, } and a comparison of the
observations OF his predecessors on this subject, TO
frame an hypothesis, which appears to offer us a So
luton OF this problem, at once satisfactory, simple
and rational.
According to the statements lately given by Prof.
Lyell, in his lectures before the Lowell Institute,
MIR. ID. supposes the great thickness of the reefs, to
have been formed by a gradual and long continued
subsistence of the original shelf of coral, while the
surface was maintained at the same level as at first,
by the unceasing additions made by the polypes.
Carrying out this principle, he attributes the peculiar
conformation of lagoon islands to the operation of
similar causes. That is to say, he considers that the
site of those islands of such a character, now sprink-
led over the whole vast coralliferous belt of ocean,
was once occupied by islands of various elevation,
surrounded as many of the same class now are, by a
fringing or shore reef; that as these have slowly
sunk, the reef has gradually receded from the shore,
and on their total disappearance left the lagoon only
to mark the place of their existence. Thus the coral
islands instead of being looked upon as the germs of
a new continent, should be contemplated as the
wrecks or rather as beacons, pointing out where lie
the wrecks of one, long since'
SIN the deep bosom of the ocean buried"
He evidently adopts the opinion that the
islands of Polynesia once formed a vast equa-
torial continent, which has subsidized, and
left the present islands as grave stones to
commemorate its former existence. The
uniformity of the geological features of the
several groups, favors this opinion; and per-
haps volcanic agency was the active cause
OF the submergence. AT all events, the chief
islands exhibit incontestible proofs of its pow
erful effects, and the low coral islands are
based upon lodges of lava. AT the present
time he judges the whole of Polynesia to be