Coral Reefs; Volcanic Islands; South American Geology — CompleteDarwin, Charles
Science
Coral Reefs; Volcanic Islands; South American Geology — Complete
Darwin, Charles
Beagle Expedition (1831-1836); Coral reefs and islands; Geology -- South America; Islands; Volcanoes
which the Loo Choo reefs lie from the land with relation to the
probable submarine inclination, and in the absence of an interior deep
water-moat or channel, parallel to the land. Hence, I have classed
these reefs with fringing-reefs, and coloured them red.—PESCADORES
(west of Formosa). Dampier (vol. i, p. 416), has compared the
appearance of the land to the southern parts of England. The islands
are interlaced with coral-reefs; but as the water is very shoal, and as
spits of sand and gravel (Horsburgh, vol. ii, p. 450) extend far out
from them, it is impossible to draw any inferences regarding the nature
of the reefs.
CHINA SEA.—Proceeding from north to south, we first meet the _Pratas
Shoal_ (lat. 20° N.) which, according to Horsburgh (vol. ii, p. 335),
is composed of coral, is of a circular form, and has a low islet on it.
The reef is on a level with the water’s edge, and when the sea runs
high, there are breakers mostly all round, “but the water within seems
pretty deep in some places; although steep-to in most parts outside,
there appear to be several parts where a ship might find anchorage
outside the breakers;” coloured blue.—The _ Paracells_ have been
accurately surveyed by Captain D. Ross, and charts on a large scale
published: but few low islets have been formed on these shoals, and
this seems to be a general circumstance in the China Sea; the sea close
outside the reefs is very deep; several of them have a lagoon-like
structure; or separate islets (_Prattle, Robert, Drummond_, etc.) are
so arranged round a moderately shallow space, as to appear as if they
had once formed one large atoll.—_Bombay Shoal_ (one of the Paracells)
has the form of an annular reef, and is “apparently deep within;” it
seems to have an entrance (Horsburgh, vol. ii, p. 332) on its west
side; it is very steep outside.—_Discovery Shoal_, also is of an oval
form, with a lagoon-like space within, and three openings leading into
it, in which there is a depth from two to twenty fathoms. Outside, at
the distance (Horsburgh, vol. ii, p. 333) of only twenty yards from the
reef, soundings could not be obtained. The Paracells are coloured
blue.—_Macclesfield Bank_: this is a coral-bank of great size, lying
east of the Paracells; some parts of the bank are level, with a sandy
bottom, but, generally, the depth is very irregular. It is intersected
by deep cuts or channels. I am not able to perceive in the published
charts (its limits, however, are not very accurately known) whether the
central part is deeper, which I suspect is the case, as in the Great
Chagos Bank, in the Indian Ocean; not coloured.—_Scarborough Shoal_:
this coral-shoal is engraved with a double row of crosses, forming a
circle, as if there was deep water within the reef: close outside there
was no bottom, with a hundred fathoms; coloured blue.—The sea off the
west coast of Palawan and the northern part of Borneo is strewed with
shoals: _Swallow Shoal_, according to Horsburgh (vol. ii, p. 431) “is
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account