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Appendix. 4
JAVA.
My information regarding the reefs of this great island is derived from the
chart just mentioned. The greater part of MADUARA is represented in it as
regularly fringed, and likewise portions of the coast of Java immediately
south of it. Dr. Horsfield informs me that coral is very abundant near
SOURABAYA. The islets and parts of the N. coast of Java, west of POINT
BUANG, or JAPARA, are fringed by reefs, said to be of coral. LUBECK, or
BAVIAN Islands, lying at some distance from the shore of Java, are
regularly fringed by coral-reefs. CARIMON JAVA appears equally so, though
it is not directly said that the reefs are of coral; there is a depth
between thirty and forty fathoms round these islands. Parts of the shores
of SUNDA STRAIT, where the water is from forty to eighty fathoms deep, and
the islets near BATAVIA appear in several charts to be fringed. In the
Dutch chart the southern shore, in the narrowest part of the island, is in
two places fringed by reefs of coral. West of SEGORROWODEE Bay, and the
extreme S.E. and E. portions are likewise fringed by coral-reefs; all the
above-mentioned places coloured red.
MACASSAR STRAIT.
The EAST COAST OF Borneo appears, in most parts, free from reefs, and where
they occur, as on the east coast of PAMAROONG, the sea is very shallow;
hence no part is coloured. In MACASSAR Strait itself, in about latitude 2
deg S., there are many small islands with coral-shoals projecting far from
them. There are also (old charts by Dalrymple) numerous little flats of
coral, not rising to the surface of the water, and shelving suddenly from
five fathoms to no bottom with fifty fathoms; they do not appear to have a
lagoon-like structure. There are similar coral-shoals a little farther
south; and in latitude 4 deg 55' there are two, which are engraved from
modern surveys, in a manner which might represent an annular reef with deep
water inside: Captain Moresby, however, who was formerly in this sea,
doubts this fact, so that I have left them uncoloured: at the same time I
may remark, that these two shoals make a nearer approach to the atoll-like
structure than any other within the E. Indian Archipelago. Southward of
these shoals there are other low islands and irregular coral-reefs; and in
the space of sea, north of the great volcanic chain, from Timor to Java, we
have also other islands, such as the POSTILLIONS, KALATOA, TOKAN-BESSEES,
etc., which are chiefly low, and are surrounded by very irregular and
distant reefs. From the imperfect charts I have seen, I have not been able
to decide whether they belong to the atoll or barrier-classes, or whether
they merely fringe submarine banks, and gently sloping land. In the Bay of
BONIN, between the two southern arms of Celebes, there are numerous coral-
reefs; but none of them seem to have an atoll-like structure. I have,
therefore, not coloured any of the islands in this part of the sea; I think
it, however, exceedingly probable that some of them ought to be blue. I
may add that there is a harbour on the S.E. coast of BOUTON which,
according to an old chart, is formed by a reef, parallel to the shore, with
deep water within; and in the "Voyage of the 'Coquille'," some neighbouring
islands are represented with reefs a good way distant, but I do not know
whether with deep water within. I have not thought the evidence sufficient
to permit me to colour them.
SUMATRA.
Commencing with the west coast and outlying islands, ENGANO Island is
represented in the published chart as surrounded by a narrow reef, and
Napier, in his "Sailing Directions," speaks of the reef being of coral
(also Horsburgh, volume ii., page 115); coloured red.--RAT Island (3 deg
51' S.) is surrounded by reefs of coral, partly dry at low water,
(Horsburgh, volume ii., page 96).--TRIESTE Island (4 deg 2' S.). The shore
is represented in a chart which I saw at the India House, as fringed in
such a manner, that I feel sure the fringe consists of coral; but as the
island is so low, that the sea sometimes flows quite over it (Dampier,
"Voyage," volume i., page 474), I have not coloured it.--PULO DOOA
(latitude 3 deg). In an old chart it is said there are chasms in the reefs
round the island, admitting boats to the watering-place, and that the
southern islet consists of a mass of sand and coral.--PULO PISANG;
Horsburgh (volume ii., page 86) says that the rocky coral-bank, which
stretches about forty yards from the shore, is steep to all round: in a
chart, also, which I have seen, the island is represented as regularly
fringed.--PULO MINTAO is lined with reefs on its west side (Horsburgh,
volume ii., page 107).--PULO BANIAK; the same authority (volume ii., page
105), speaking of a part, says it is faced with coral-rocks.--MINGUIN (3
deg 36' N.). A coral-reef fronts this place, and projects into the sea
nearly a quarter of a mile ("Notices of the Indian Arch." published at
Singapore, page 105).--PULO BRASSA (5 deg 46' N.). A reef surrounds it at
a cable's length (Horsburgh, volume ii., page 60). I have coloured all the
above-specified points red. I may here add, that both Horsburgh and Mr.
Moor (in the "Notices" just alluded to) frequently speak of the numerous
reefs and banks of coral on the west coast of Sumatra; but these nowhere
have the structure of a barrier-reef, and Marsden ("History of Sumatra")
states, that where the coast is flat, the fringing-reefs extend furthest
from it. The northern and southern points, and the greater part of the
east coast, are low, and faced with mud banks, and therefore without coral.
NICOBAR ISLANDS.
The chart represents the islands of this group as fringed by reefs. With
regard to GREAT NICOBAR, Captain Moresby informs me, that it is fringed by
reefs of coral, extending between two and three hundred yards from the
shore. The NORTHERN NICOBARS appear so regularly fringed in the published
charts, that I have no doubt the reefs are of coral. This group,
therefore, is coloured red.
ANDAMAN ISLANDS.
From an examination of the MS. chart, on a large scale, of this island, by
Captain Arch. Blair, in the Admiralty, several portions of the coast appear
fringed; and as Horsburgh speaks of coral-reefs being numerous in the
vicinity of these islands, I should have coloured them red, had not some
expressions in a paper in the "Asiatic Researches" (volume iv., page 402)
led me to doubt the existence of reefs; uncoloured.
The coast of MALACCA, TENASSERIM and the coasts northward, appear in the
greater part to be low and muddy: where reefs occur, as in parts of
MALACCA STRAITS, and near SINGAPORE, they are of the fringing kind; but the
water is so shoal, that I have not coloured them. In the sea, however,
between Malacca and the west coast of Borneo, where there is a greater
depth from forty to fifty fathoms, I have coloured red some of the groups,
which are regularly fringed. The northern NATUNAS and the ANAMBAS Islands
are represented in the charts on a large scale, published in the "Atlas of
the Voyage of the 'Favourite'," as fringed by reefs of coral, with very
shoal water within them.--TUMBELAN and BUNOA Islands (1 deg N.) are
represented in the English charts as surrounded by a very regular fringe.--
ST. BARBES (0 deg 15' N.) is said by Horsburgh (volume ii., page 279) to be
fronted by a reef, over which boats can land only at high water.--The shore
of BORNEO at TUNJONG APEE is also fronted by a reef, extending not far from
the land (Horsburgh, volume ii., page 468). These places I have coloured
red; although with some hesitation, as the water is shallow. I might
perhaps have added PULO LEAT, in Gaspar Strait, LUCEPARA, and CARIMATA; but
as the sea is confined and shallow, and the reefs not very regular, I have
left them uncoloured.
The water shoals gradually towards the whole west coast of BORNEO: I
cannot make out that it has any reefs of coral. The islands, however, off
the northern extremity, and near the S.W. end of PALAWAN, are fringed by
very distant coral-reefs; thus the reefs in the case of BALABAC are no less
than five miles from the land; but the sea, in the whole of this district,
is so shallow, that the reefs might be expected to extend very far from the
land. I have not, therefore, thought myself authorised to colour them.
The N.E. point of Borneo, where the water is very shoal, is connected with
Magindanao by a chain of islands called the SOOLOO ARCHIPELAGO, about which
I have been able to obtain very little information; PANGOOTARAN, although
ten miles long, entirely consists of a bed of coral-rock ("Notices of E.
Indian Arch." page 58): I believe from Horsburgh that the island is low;
not coloured.--TAHOW BANK, in some old charts, appears like a submerged
atoll; not coloured. Forrest ("Voyage," page 21) states that one of the
islands near Sooloo is surrounded by coral-rocks; but there is no distant
reef. Near the S. end of BASSELAN, some of the islets in the chart
accompanying Forrest's "Voyage," appear fringed with reefs; hence I have
coloured, though unwillingly, parts of the Sooloo group red. The sea
between Sooloo and Palawan, near the shoal coast of Borneo, is interspersed
with irregular reefs and shoal patches; not coloured: but in the northern
part of this sea, there are two low islets, CAGAYANES and CAVILLI,
surrounded by extensive coral-reefs; the breakers round the latter
(Horsburgh, volume ii., page 513) extend five or six miles from a sandbank,
which forms the only dry part; these breakers are steep to outside; there
appears to be an opening through them on one side, with four or five
fathoms within: from this description, I strongly suspect that Cavilli
ought to be considered an atoll; but, as I have not seen any chart of it,
on even a moderately large scale, I have not coloured it. The islets off
the northern end of PALAWAN, are in the same case as those off the southern
end, namely they are fringed by reefs, some way distant from the shore, but
the water is exceedingly shallow; uncoloured. The western shore of Palawan
will be treated of under the head of China Sea.
PHILIPPINE ARCHIPELAGO.
A chart on a large scale of APPOO SHOAL, which lies near the S.E. coast of
Mindoro, has been executed by Captain D. Ross: it appears atoll-formed,
but with rather an irregular outline; its diameter is about ten miles;
there are two well-defined passages leading into the interior lagoon, which
appears open; close outside the reef all round, there is no bottom with
seventy fathoms; coloured blue.--MINDORO: the N.W. coast is represented in
several charts, as fringed by a reef, and LUBAN Island is said, by
Horsburgh (volume ii., page 436), to be "lined by a reef."--LUZON: Mr.
Cuming, who has lately investigated with so much success the Natural
History of the Philippines, informs me, that about three miles of the shore
north of Point St. Jago, is fringed by a reef; as are (Horsburgh, volume
ii., page 437) the Three Friars off Silanguin Bay. Between Point Capones
and Playa Honda, the coast is "lined by a coral-reef, stretching out nearly
a mile in some places," (Horsburgh); and Mr. Cuming visited some fringing-
reefs on parts of this coast, namely, near Puebla, Iba, and Mansinglor. In
the neighbourhood of Solon-solon Bay, the shore is lined (Horsburgh ii.,
page 439) by coral-reefs, stretching out a great way: there are also reefs
about the islets off Solamague; and as I am informed by Mr. Cuming, near
St. Catalina, and a little north of it. The same gentleman informs me
there are reefs on the S.E. point of this island in front of Samar,
extending from Malalabon to Bulusan. These appear to be the principal
fringing-reefs on the coasts of Luzon; and they have all been coloured red.
Mr. Cuming informs me that none of them have deep water within; although it
appears from Horsburgh that some few extend to a considerable distance from
the shore. Within the Philippine Archipelago, the shores of the islands do
not appear to be commonly fringed, with the exception of the S. shore of
MASBATE, and nearly the whole of BOHOL; which are both coloured red. On
the S. shore of MAGINDANAO, Bunwoot Island is surrounded (according to
Forrest, "Voyage," page 253), by a coral-reef, which in the chart appears
one of the fringing class. With respect to the eastern coasts of the whole
Archipelago, I have not been able to obtain any account.
BABUYAN ISLANDS.
Horsburgh says (volume ii., page 442), coral-reefs line the shores of the
harbour in Fuga; and the charts show there are other reefs about these
islands. Camiguin has its shore in parts lined by coral-rock (Horsburgh,
page 443); about a mile off shore there is between thirty and thirty-five
fathoms. The plan of Port San Pio Quinto shows that its shores are fringed
with coral; coloured red.--BASHEE Islands: Horsburgh, speaking of the
southern part of the group (volume ii., page 445) says the shores of both
islands are fortified by a reef, and through some of the gaps in it, the
natives can pass in their boats in fine weather; the bottom near the land
is coral-rock. From the published charts, it is evident that several of
these islands are most regularly fringed; coloured red. The northern
islands are left uncoloured, as I have been unable to find any account of
them.--FORMOSA. The shores, especially the western one, seem chiefly
composed of mud and sand, and I cannot make out that they are anywhere
lined by reefs; except in a harbour (Horsburgh, volume ii., page 449) at
the extreme northern point: hence, of course, the whole of this island is
left uncoloured. The small adjoining islands are in the same case.--
PATCHOW, or MADJIKO-SIMA GROUPS. PATCHUSON has been described by Captain
Broughton ("Voy. to the N. Pacific," page 191); he says, the boats, with
some difficulty, found a passage through the coral-reefs, which extend
along the coast, nearly half a mile off it. The boats were well sheltered
within the reef; but it does not appear that the water is deep there.
Outside the reef the depth is very irregular, varying from five to fifty
fathoms; the form of the land is not very abrupt; coloured red.--TAYPIN-
SAN; from the description given (page 195) by the same author, it appears
that a very irregular reef extends, to the distance of several miles, from
the southern island; but whether it encircles a space of deep water is not
evident; nor, indeed, whether these outlying reefs are connected with those
more immediately adjoining the land; left uncoloured. I may here just add
that the shore of KUMI (lying west of Patchow), has a narrow reef attached
to it in the plan of it, in La Peyrouse's "Atlas;" but it does not appear
in the account of the voyage that it is of coral; uncoloured.--LOO CHOO.
The greater part of the coast of this moderately hilly island, is skirted
by reefs, which do not extend far from the shore, and which do not leave a
channel of deep water within them, as may be seen in the charts
accompanying Captain B. Hall's voyage to Loo Choo (see also remarks in
Appendix, pages xxi. and xxv.). There are, however, some ports with deep
water, formed by reefs in front of valleys, in the same manner as happens
at Mauritius. Captain Beechey, in a letter to me, compares these reefs
with those encircling the Society Islands; but there appears to me a marked
difference between them, in the less distance at 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 deg 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 shoals:
SWALLOW SHOAL, according to Horsburgh (volume ii., page 431) "is formed,
LIKE MOST of the shoals hereabouts, of a belt of coral-rocks, "with a basin
of deep water within."--HALF-MOON SHOAL has a similar structure; Captain D.
Ross describes it, as a narrow belt of coral-rock, "with a basin of deep
water in the centre," and deep sea close outside.--BOMBAY SHOAL appears
(Horsburgh, volume ii., page 432) "to be a basin of smooth water surrounded
by breakers." These three shoals I have coloured blue.--The PARAQUAS
SHOALS are of a circular form, with deep gaps running through them; not
coloured.--A bank gradually shoaling to the depth of thirty fathoms,
extends to a distance of about twenty miles from the northern part of
BORNEO, and to thirty miles from the northern part of PALAWAN. Near the
land this bank appears tolerably free from danger, but a little further out
it is thickly studded with coral-shoals, which do not generally rise quite
to the surface; some of them are very steep-to, and others have a fringe of
shoal-water round them. I should have thought that these shoals had level
surfaces, had it not been for the statement made by Horsburgh "that most of
the shoals hereabouts are formed of a belt of coral." But, perhaps that
expression was more particularly applied to the shoals further in the
offing. If these reefs of coral have a lagoon-like structure, they should
have been coloured blue, and they would have formed an imperfect barrier in
front of Palawan and the northern part of Borneo. But, as the water is not
very deep, these reefs may have grown up from inequalities on the bank: I
have not coloured them.--The coast of CHINA, TONQUIN, and COCHIN-CHINA,
forming the western boundary of the China Sea, appear to be without reefs:
with regard to the two last-mentioned coasts, I speak after examining the
charts on a large scale in the "Atlas of the Voyage of the 'Favourite'."
INDIAN OCEAN.
SOUTH KEELING atoll has been specially described. Nine miles north of it
lies North Keeling, a very small atoll, surveyed by the "Beagle," the
lagoon of which is dry at low water.--CHRISTMAS Island, lying to the east,
is a high island, without, as I have been informed by a person who passed
it, any reefs at all.--CEYLON: a space about eighty miles in length of the
south-western and southern shores of these islands has been described by
Mr. Twynam ("Naut. Mag." 1836, pages 365 and 518); parts of this space
appear to be very regularly fringed by coral-reefs, which extend from a
quarter to half a mile from the shore. These reefs are in places breached,
and afford safe anchorage for the small trading craft. Outside, the sea
gradually deepens; there is forty fathoms about six miles off shore: this
part I have coloured red. In the published charts of Ceylon there appear
to be fringing-reefs in several parts of the south-eastern shores, which I
have also coloured red.--At Venloos Bay the shore is likewise fringed.
North of Trincomalee there are also reefs of the same kind. The sea off
the northern part of Ceylon is exceedingly shallow; and therefore I have
not coloured the reefs which fringe portions of its shores, and the
adjoining islets, as well as the Indian promontory of MADURA.
CHAGOS, MALDIVA, AND LACCADIVE ARCHIPELAGOES.
These three great groups which have already been often noticed, are now
well-known from the admirable surveys of Captain Moresby and Lieutenant
Powell. The published charts, which are worthy of the most attentive
examination, at once show that the CHAGOS and MALDIVA groups are entirely
formed of great atolls, or lagoon-formed reefs, surmounted by islets. In
the LACCADIVE group, this structure is less evident; the islets are low,
not exceeding the usual height of coral-formations (see Lieutenant Wood's
account, "Geographical Journal", volume vi., page 29), and most of the
reefs are circular, as may be seen in the published charts; and within
several of them, as I am informed by Captain Moresby, there is deepish
water; these, therefore, have been coloured blue. Directly north, and
almost forming part of this group, there is a long, narrow, slightly curved
bank, rising out of the depths of the ocean, composed of sand, shells, and
decayed coral, with from twenty-three to thirty fathoms on it. I have no
doubt that it has had the same origin with the other Laccadive banks; but
as it does not deepen towards the centre I have not coloured it. I might
have referred to other authorities regarding these three archipelagoes; but
after the publication of the charts by Captain Moresby, to whose personal
kindness in giving me much information I am exceedingly indebted, it would
have been superfluous.
SAHIA DE MALHA bank consists of a series of narrow banks, with from eight
to sixteen fathoms on them; they are arranged in a semicircular manner,
round a space about forty fathoms deep, which slopes on the S.E. quarter to
unfathomable depths; they are steep-to on both sides, but more especially
on the ocean-side. Hence this bank closely resembles in structure, and I
may add from Captain Moresby's information in composition, the Pitt's Bank
in the Chagos group; and the Pitt's Bank, must, after what has been shown
of the Great Chagos Bank, be considered as a sunken, half-destroyed atoll;
hence coloured blue.--CARGADOS CARAJOS BANK. Its southern portion consists
of a large, curved, coral-shoal, with some low islets on its eastern edge,
and likewise some on the western side, between which there is a depth of
about twelve fathoms. Northward, a great bank extends. I cannot (probably
owing to the want of perfect charts) refer this reef and bank to any
class;--therefore not coloured.--ILE DE SABLE is a little island, lying
west of C. Carajos, only some toises in height ("Voyage of the
'Favourite'," volume i., page 130); it is surrounded by reefs; but its
structure is unintelligible to me. There are some small banks north of it,
of which I can find no clear account.--MAURITIUS. The reefs round this
island have been described in the chapter on fringing-reefs; coloured red.
--RODRIGUEZ. The coral-reefs here are exceedingly extensive; in one part
they project even five miles from the shore. As far as I can make out,
there is no deep-water moat within them; and the sea outside does not
deepen very suddenly. The outline, however, of the land appears to be
("Life of Sir J. Makintosh," volume ii., page 165) hilly and rugged. I am
unable to decide whether these reefs belong to the barrier class; as seems
probable from their great extension, or to the fringing class; uncoloured.
--BOURBON. The greater part of the shores of this island are without
reefs; but Captain Carmichael (Hooker's "Bot. Misc.") states that a
portion, fifteen miles in length, on the S.E. side, is imperfectly fringed
with coral reefs: I have not thought this sufficient to colour the island.
SEYCHELLES.
The rocky islands of primary formation, composing this group, rise from a
very extensive and tolerably level bank, having a depth between twenty and
forty fathoms. In Captain Owen's chart, and in that in the "Atlas of the
Voyage of the 'Favourite'," it appears that the east side of MAHE and the
adjoining islands of ST. ANNE and CERF, are regularly fringed by coral-reefs.
A portion of the S.E. part of CURIEUSE Island, the N., and part of
the S.W. shore of PRASLIN Island, and the whole west side of DIGUE Island,
appear fringed. From a MS. account of these islands by Captain F. Moresby,
in the Admiralty, it appears that SILHOUETTE is also fringed; he states
that all these islands are formed of granite and quartz, that they rise
abruptly from the sea, and that "coral-reefs have grown round them, and
project for some distance." Dr. Allan, of Forres, who visited these
islands, informs me that there is no deep water between the reefs and the
shore. The above specified points have been coloured red. AMIRANTES
Islands: The small islands of this neighbouring group, according to the
MS. account of them by Captain F. Moresby, are situated on an extensive
bank; they consist of the debris of corals and shells; are only about
twenty feet in height, and are environed by reefs, some attached to the
shore, and some rather distant from it.--I have taken great pains to
procure plans and information regarding the several islands lying between
S.E. and S.W. of the Amirantes, and the Seychelles; relying chiefly on
Captain F. Moresby and Dr. Allan, it appears that the greater number,
namely--PLATTE, ALPHONSE, COETIVI, GALEGA, PROVIDENCE, ST. PIERRE, ASTOVA,
ASSOMPTION, and GLORIOSO, are low, formed of sand or coral-rock, and
irregularly shaped; they are situated on very extensive banks, and are
connected with great coral-reefs. Galega is said by Dr. Allan, to be
rather higher than the other islands; and St. Pierre is described by
Captain F. Moresby, as being cavernous throughout, and as not consisting of
either limestone or granite. These islands, as well as the Amirantes,
certainly are not atoll-formed, and they differ as a group from every other
group with which I am acquainted; I have not coloured them; but probably
the reefs belong to the fringing class. Their formation is attributed,
both by Dr. Allan and Captain F. Moresby, to the action of the currents,
here exceedingly violent, on banks, which no doubt have had an independent
geological origin. They resemble in many respects some islands and banks
in the West Indies, which owe their origin to a similar agency, in
conjunction with an elevation of the entire area. In close vicinity to the
several islands, there are three others of an apparently different nature:
first, JUAN DE NOVA, which appears from some plans and accounts to be an
atoll; but from others does not appear to be so; not coloured. Secondly
COSMOLEDO; "this group consists of a ring of coral, ten leagues in
circumference, and a quarter of a mile broad in some places, enclosing a
magnificent lagoon, into which there did not appear a single opening"
(Horsburgh, volume i., page 151); coloured blue. Thirdly, ALDABRA; it
consists of three islets, about twenty-five feet in height, with red cliffs
(Horsburgh, volume i., page 176) surrounding a very shallow basin or
lagoon. The sea is profoundly deep close to the shore. Viewing this
island in a chart, it would be thought an atoll; but the foregoing
description shows that there is something different in its nature; Dr.
Allan also states that it is cavernous, and that the coral-rock has a
vitrified appearance. Is it an upheaved atoll, or the crater of a
volcano?--uncoloured.
COMORO GROUP.
MAYOTTA, according to Horsburgh (volume i., page 216, 4th edition), is
completely surrounded by a reef, which runs at the distance of three, four,
and in some places even five miles from the land; in an old chart,
published by Dalrymple, a depth in many places of thirty-six and thirty-eight
fathoms is laid down within the reef. In the same chart, the space
of open water within the reef in some parts is even more than three miles
wide: the land is bold and peaked; this island, therefore, is encircled by
a well-characterised barrier-reef, and is coloured pale blue.--JOHANNA;
Horsburgh says (volume I. page 217) this island from the N.W. to the S.W.
point, is bounded by a reef, at the distance of two miles from the shore;
in some parts, however, the reef must be attached, since Lieutenant Boteler
("Narr." volume i., page 161) describes a passage through it, within which
there is room only for a few boats. Its height, as I am informed by Dr.
Allan, is about 3,500 feet; it is very precipitous, and is composed of
granite, greenstone, and quartz; coloured blue.--MOHILLA; on the S. side of
this island there is anchorage, in from thirty to forty-five fathoms,
between a reef and the shore (Horsburgh, volume i., page 214); in Captain
Owen's chart of Madagascar, this island is represented as encircled;
coloured blue.--GREAT COMORO Island is, as I am informed by Dr. Allan,
about 8,000 feet high, and apparently volcanic; it is not regularly
encircled; but reefs of various shapes and dimensions, jut out from every
headland on the W., S., and S.E. coasts, inside of which reefs there are
channels, often parallel with the shore, with deep water. On the
north-western coasts the reefs appear attached to the shores. The land near
the coast is in some places bold, but generally speaking it is flat;
Horsburgh says (volume i., page 214) the water is profoundly deep close to
the SHORE, from which expression I presume some parts are without reefs.
From this description I apprehend the reef belongs to the barrier class;
but I have not coloured it, as most of the charts which I have seen,
represent the reefs round it as very much less extensive than round the
other islands in the group.
MADAGASCAR.
My information is chiefly derived from the published charts by Captain
Owen, and the accounts given by him and by Lieutenant Boteler. Commencing
at the S.W. extremity of the island; towards the northern part of the STAR
BANK (in latitude 25 deg S.) the coast for ten miles is fringed by a reef;
coloured red. The shore immediately S. of ST. AUGUSTINE'S BAY appears
fringed; but TULLEAR Harbour, directly N. of it, is formed by a narrow reef
ten miles long, extending parallel to the shore, with from four to ten
fathoms within it. If this reef had been more extensive, it must have been
classed as a barrier-reef; but as the line of coast falls inwards here, a
submarine bank perhaps extends parallel to the shore, which has offered a
foundation for the growth of the coral; I have left this part uncoloured.
From latitude 22 deg 16' to 21 deg 37', the shore is fringed by coral-reefs
(see Lieutenant Boteler's "Narrative," volume ii., page 106), less than a
mile in width, and with shallow water within. There are outlying
coral-shoals in several parts of the offing, with about ten fathoms between
them and the shore, and the depth of the sea one mile and a half seaward, is
about thirty fathoms. The part above specified is engraved on a large
scale; and as in the charts on rather a smaller scale the same fringe of
reef extends as far as latitude 33 deg 15'; I have coloured the whole of
this part of the coast red. The islands of JUAN DE NOVA (in latitude 17
deg S.) appear in the charts on a large scale to be fringed, but I have not
been able to ascertain whether the reefs are of coral; uncoloured. The
main part of the west coast appears to be low, with outlying sandbanks,
which, Lieutenant Boteler (volume ii., page 106) says, "are faced on the
edge of deep water by a line of sharp-pointed coral-rocks." Nevertheless I
have not coloured this part, as I cannot make out by the charts that the
coast itself is fringed. The headlands of NARRENDA and PASSANDAVA Bays (14
deg 40') and the islands in front of RADAMA HARBOUR are represented in the
plans as regularly fringed, and have accordingly been coloured red. With
respect to the EAST COAST OF MADAGASCAR, Dr. Allan informs me in a letter,
that the whole line of coast, from TAMATAVE, in 18 deg 12', to C. AMBER, at
the extreme northern point of the island, is bordered by coral-reefs. The
land is low, uneven, and gradually rising from the coast. From Captain
Owen's charts, also, the existence of these reefs, which evidently belong
to the fringing class, on some parts, namely N. of BRITISH SOUND, and near
NGONCY, of the above line of coast might have been inferred. Lieutenant
Boteler (volume i., page 155) speaks of "the reef surrounding the island of
ST. MARY'S at a small distance from the shore." In a previous chapter I
have described, from the information of Dr. Allan, the manner in which the
reefs extend in N.E. lines from the headlands on this coast, thus sometimes
forming rather deep channels within them, this seems caused by the action
of the currents, and the reefs spring up from the submarine prolongations
of the sandy headlands. The above specified portion of the coast is
coloured red. The remaining S.E. portions do not appear in any published
chart to possess reefs of any kind; and the Rev. W. Ellis, whose means of
information regarding this side of Madagascar have been extensive, informs
me he believes there are none.
EAST COAST OF AFRICA.
Proceeding from the northern part, the coast appears, for a considerable
space, without reefs. My information, I may here observe, is derived from
the survey by Captain Owen, together with his narrative; and that by
Lieutenant Boteler. At MUKDEESHA (10 deg 1' N.) there is a coral-reef
extending four or five miles along the shore (Owen's "Narr." volume i, page
357) which in the chart lies at the distance of a quarter of a mile from
the shore, and has within it from six to ten feet water: this then is a
fringing-reef, and is coloured red. From JUBA, a little S. of the equator,
to LAMOO (in 2 deg 20' S.) "the coast and islands are formed of madrepore"
(Owen's "Narrative," volume i., page 363). The chart of this part
(entitled DUNDAS Islands), presents an extraordinary appearance; the coast
of the mainland is quite straight and it is fronted at the average distance
of two miles, by exceedingly narrow, straight islets, fringed with reefs.
Within the chain of islets, there are extensive tidal flats and muddy bays,
into which many rivers enter; the depths of these spaces varies from one to
four fathoms--the latter depth not being common, and about twelve feet the
average. Outside the chain of islets, the sea, at the distance of a mile,
varies in depth from eight to fifteen fathoms. Lieutenant Boteler ("Narr."
volume i., page 369) describes the muddy bay of PATTA, which seems to
resemble other parts of this coast, as fronted by small, narrow, level
islets formed of decomposing coral, the margin of which is seldom of
greater height than twelve feet, overhanging the rocky surface from which
the islets rise. Knowing that the islets are formed of coral, it is, I
think, scarcely possible to view the coast, and not at once conclude that
we here see a fringing-reef, which has been upraised a few feet: the
unusual depth of from two to four fathoms within some of these islets, is
probably due to muddy rivers having prevented the growth of coral near the
shore. There is, however, one difficulty on this view, namely, that before
the elevation took place, which converted the reef into a chain of islets,
the water must apparently have been still deeper; on the other hand it may
be supposed that the formation of a nearly perfect barrier in front, of so
large an extent of coast, would cause the currents (especially in front of
the rivers), to deepen their muddy beds. When describing in the chapter on
fringing-reefs, those of Mauritius, I have given my reasons for believing
that the shoal spaces within reefs of this kind, must, in many instances,
have been deepened. However this may be, as several parts of this line of
coast are undoubtedly fringed by living reefs, I have coloured it red.--
MALEENDA (3 deg 20' S.). In the plan of the harbour, the south headland
appears fringed; and in Owen's chart on a larger scale, the reefs are seen
to extend nearly thirty miles southward; coloured red.--MOMBAS (4 deg 5'
S.). The island which forms the harbour, "is surrounded by cliffs of
madrepore, capable of being rendered almost impregnable" (Owen's "Narr."
volume i., page 412). The shore of the mainland N. and S. of the harbour,
is most regularly fringed by a coral-reef at a distance from half a mile to
one mile and a quarter from the land; within the reef the depth is from
nine to fifteen feet; outside the reef the depth at rather less than half a
mile is thirty fathoms. From the charts it appears that a space about
thirty-six miles in length, is here fringed; coloured red.--PEMBA (5 deg
S.) is an island of coral-formation, level, and about two hundred feet in
height (Owen's "Narr." volume i., page 425); it is thirty-five miles long,
and is separated from the mainland by a deep sea. The outer coast is
represented in the chart as regularly fringed; coloured red. The mainland
in front of Pemba is likewise fringed; but there also appear to be some
outlying reefs with deep water between them and the shore. I do not
understand their structure, either from the charts or the description,
therefore have not coloured them.--ZANZIBAR resembles Pemba in most
respects; its southern half on the western side and the neighbouring islets
are fringed; coloured red. On the mainland, a little S. of Zanzibar, there
are some banks parallel to the coast, which I should have thought had been
formed of coral, had it not been said (Boteler's "Narr." volume ii., page
39) that they were composed of sand; not coloured.--LATHAM'S BANK is a
small island, fringed by coral-reefs; but being only ten feet high, it has
not been coloured.--MONFEEA is an island of the same character as Pemba;
its outer shore is fringed, and its southern extremity is connected with
Keelwa Point on the mainland by a chain of islands fringed by reefs;
coloured red. The four last-mentioned islands resemble in many respects
some of the islands in the Red Sea, which will presently be described.--
KEELWA. In a plan of the shore, a space of twenty miles N. and S. of this
place is fringed by reefs, apparently of coral: these reefs are prolonged
still further southward in Owen's general chart. The coast in the plans of
the rivers LINDY and MONGHOW (9 deg 59' and 10 deg 7' S.) has the same
structure; coloured red.--QUERIMBA Islands (from 10 deg 40' to 13 deg S.).
A chart on a large scale is given of these islands; they are low, and of
coral-formation (Boteler's "Narr." volume ii., page 54); and generally have
extensive reefs projecting from them which are dry at low water, and which
on the outside rise abruptly from a deep sea: on their insides they are
separated from the continent by a channel, or rather a succession of bays,
with an average depth of ten fathoms. The small headlands on the continent
also have coral-banks attached to them; and the Querimba islands and banks
are placed on the lines of prolongation of these headlands, and are
separated from them by very shallow channels. It is evident that whatever
cause, whether the drifting of sediment or subterranean movements, produced
the headlands, likewise produced, as might have been expected, submarine
prolongations to them; and these towards their outer extremities, have
since afforded a favourable basis for the growth of coral-reefs, and
subsequently for the formation of islets. As these reefs clearly belong to
the fringing class, the Querimba islands have been coloured red.--MONABILA
(13 deg 32' S.). In the plan of this harbour, the headlands outside are
fringed by reefs apparently of coral; coloured red.--MOZAMBIQUE (150 deg
S.) The outer part of the island on which the city is built, and the
neighbouring islands, are fringed by coral-reefs; coloured red. From the
description given in Owen's "Narr." (volume i., page 162), the shore from
MOZAMBIQUE to DELAGOA BAY appears to be low and sandy; many of the shoals
and islets off this line of coast are of coral-formation; but from their
small size and lowness, it is not possible, from the charts, to know
whether they are truly fringed. Hence this portion of coast is left
uncoloured, as are likewise those parts more northward, of which no mention
has been made in the foregoing pages from the want of information.
PERSIAN GULF.
From the charts lately published on a large scale by the East India
Company, it appears that several parts, especially the southern shores of
this gulf, are fringed by coral-reefs; but as the water is very shallow,
and as there are numerous sandbanks, which are difficult to distinguish on
the chart from reefs, I have not coloured the upper part red. Towards the
mouth, however, where the water is rather deeper, the islands of ORMUZ and
LARRACK, appear so regularly fringed, that I have coloured them red. There
are certainly no atolls in the Persian Gulf. The shores of IMMAUM, and of
the promontory forming the southern headland of the Persian Gulf, seem to
be without reefs. The whole S.W. part (except one or two small patches) of
ARABIA FELIX, and the shores of SOCOTRA appear from the charts and memoir
of Captain Haines ("Geographical Journal," 1839, page 125) to be without
any reefs. I believe there are no extensive coral-reefs on any part of the
coasts of INDIA, except on the low promontory of MADURA (as already
mentioned) in front of Ceylon.
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