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 (volume i., page 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, volume ii., page 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_ (latitude 20° N.) which, according to Horsburgh (volume ii.,
page 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,
volume ii., page 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,
volume ii., page 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
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