Part 4 out of 5
much as ten miles from it; coloured pale blue. A little distance northward
we have the LAUGHLAN Islands, the reefs round which are engraved in the
"Atlas of the Voyage of the 'Astrolabe'," in the same manner as in the
encircled islands of the Caroline Archipelago, the reef is, in parts, a
mile and a half from the shore, to which it does not appear to be attached;
coloured blue. At some little distance from the extremity of the Louisiade
lies the WELLS reef, described in G. Hamilton's "Voyage in H.M.S.
'Pandora'" (page 100): it is said, "We found we had got embayed in a
double reef, which will soon be an island." As this statement is only
intelligible on the supposition of the reef being crescent or horse-shoe
formed, like so many other submerged annular reefs, I have ventured to
colour it blue.
The chart in Krusenstern's "Atlas" shows that these islands are not
encircled, and as coral appears from the works of Surville, Bougainville,
and Labillardiere, to grow on their shores, this circumstance, as in the
case of the New Hebrides, is a presumption that they are fringed. I cannot
find out anything from D'Entrecasteaux's "Voyage," regarding the southern
islands of the group, so have left them uncoloured.--MALAYTA Island in a
rough MS. chart in the Admiralty has its northern shore fringed.--YSABEL
Island, the N.E. part of this island, in the same chart, is also fringed:
Mendana, speaking (Burney, volume i., page 280) of an islet adjoining the
northern coast, says it is surrounded by reefs; the shores, also of Port
Praslin appear regularly fringed.--CHOISEUL Island. In Bougainville's
"Chart of Choiseul Bay," parts of the shores are fringed by coral-reefs.--
BOUGAINVILLE Island. According to D'Entrecasteaux the western shore
abounds with coral-reefs, and the smaller islands are said to be attached
to the larger ones by reefs; all the before-mentioned islands have been
coloured red.--BOUKA Islands. Captain Duperrey has kindly informed me in a
letter that he passed close round the northern side of this island (of
which a plan is given in his "Atlas of the 'Coquille's' Voyage"), and that
it was "garnie d'une bande de recifs a fleur d'eau adherentes au rivage;"
and he infers, from the abundance of coral on the islands north and south
of Bouka, that the reef probably is of coral; coloured red.
Off the north coast of the Solomon Archipelago there are several small
groups which are little known; they appear to be low, and of
coral-formation; and some of them probably have an atoll-like structure; the
Chevallier Dillon, however, informs me that this is not the case with the
B. de CANDELARIA.--OUTONG JAVA, according to the Spanish navigator,
Maurelle, is thus characterised; but this is the only one which I have
ventured to colour blue.
The shores of the S.W. point of this island and some adjoining islets, are
fringed by reefs, as may be seen in the "Atlases of the Voyages of the
'Coquille' and 'Astrolabe'." M. Lesson observes that the reefs are open in
front of each streamlet. The DUKE OF YORK'S Island is also fringed; but
with regard to the other parts of NEW IRELAND, NEW HANOVER, and the small
islands lying northward, I have been unable to obtain any information. I
will only add that no part of New Ireland appears to be fronted by distant
reefs. I have coloured red only the above specified portions.
NEW BRITAIN AND THE NORTHERN SHORE OF NEW GUINEA.
From the charts in the "Voyage of the 'Astrolabe'," and from the "Hydrog.
Memoir," it appears that these coasts are entirely without reefs, as are
the SCHOUTEN Islands, lying close to the northern shore of New Guinea. The
western and south-western parts of New Guinea, will be treated of when we
come to the islands of the East Indian Archipelago.
From the accounts by Bougainville, Maurelle, D'Entrecasteaux, and the
scattered notices collected by Horsburgh, it appears, that some of the many
islands composing it, are high, with a bold outline; and others are very
low, small and interlaced with reefs. All the high islands appear to be
fronted by distant reefs rising abruptly from the sea, and within some of
which there is reason to believe that the water is deep. I have therefore
little doubt they are of the barrier class.--In the southern part of the
group we have ELIZABETH Island, which is surrounded by a reef at the
distance of a mile; and two miles eastward of it (Krusenstern, "Append."
1835, page 42) there is a little island containing a lagoon.--Near here,
also lies CIRCULAR-REEF (Horsburgh, "Direct." volume i., page 691, 4th
edition), "three or four miles in diameter having deep water inside with an
opening at the N.N.W. part, and on the outside steep to." I have from
these data, coloured the group pale blue, and CIRCULAR-REEF dark blue.--the
ANACHORITES, ECHEQUIER, and HERMITES, consist of innumerable low islands of
coral-formation, which probably have atoll-like forms; but not being able
to ascertain this, I have not coloured them, nor DUROUR Island, which is
described by Carteret as low.
The CAROLINE ARCHIPELAGO is now well-known, chiefly from the hydrographical
labours of Lutke; it contains about forty groups of atolls, and three
encircled islands, two of which are engraved in Figures 2 and 7, Plate I.
Commencing with the eastern part; the encircling reef round UALEN appears
to be only about half a mile from the shore; but as the land is low and
covered with mangroves ("Voyage autour du Monde," par F. Lutke, volume i.,
page 339), the real margin has not probably been ascertained. The extreme
depth in one of the harbours within the reef is thirty-three fathoms (see
charts in "Atlas of 'Coquille's' Voyage"), and outside at half a mile
distant from the reef, no bottom was obtained with two hundred and fifty
fathoms. The reef is surmounted by many islets, and the lagoon-like
channel within is mostly shallow, and appears to have been much encroached
on by the low land surrounding the central mountains; these facts show that
time has allowed much detritus to accumulate; coloured pale blue.--
POUYNIPETE, or Seniavine. In the greater part of the circumference of this
island, the reef is about one mile and three quarters distant; on the north
side it is five miles off the included high islets. The reef is broken in
several places; and just within it, the depth in one place is thirty
fathoms, and in another, twenty-eight, beyond which, to all appearance,
there was "un porte vaste et sur" (Lutke, volume ii., page 4); coloured
pale blue.--HOGOLEU or ROUG. This wonderful group contains at least
sixty-two islands, and its reef is one hundred and thirty-five miles in
circuit. Of the islands, only a few, about six or eight (see "Hydrog.
Descrip." page 428, of the "Voyage of the 'Astrolabe'," and the large
accompanying chart taken chiefly from that given by Duperrey) are high, and
the rest are all small, low, and formed on the reef. The depth of the great
interior lake has not been ascertained; but Captain D'Urville appears to have
entertained no doubt about the possibility of taking in a frigate. The
reef lies no less than fourteen miles distant from the northern coasts of
the interior high islands, seven from their western sides, and twenty from
the southern; the sea is deep outside. This island is a likeness on a
grand scale to the Gambier group in the Low Archipelago. Of the groups of
low (In D'Urville and Lottin's chart, Peserare is written with capital
letters; but this evidently is an error, for it is one of the low islets on
the reef of Namonouyto (see Lutke's charts)--a regular atoll.) islands
forming the chief part of the Caroline Archipelago, all those of larger
size, have the true atoll-structure (as may be seen in the "Atlas" by
Captain Lutke), and some even of the very small ones, as MACASKILL and
DUPERREY, of which plans are given in the "Atlas of the 'Coquille's'
Voyage." There are, however, some low small islands of coral-formation,
namely OLLAP, TAMATAM, BIGALI, SATAHOUAL, which do not contain lagoons; but
it is probable that lagoons originally existed, but have since filled up:
Lutke (volume ii., page 304) seems to have thought that all the low
islands, with only one exception, contained lagoons. From the sketches,
and from the manner in which the margins of these islands are engraved in
the "Atlas of the Voyage of the 'Coquille'," it might have been thought
that they were not low; but by a comparison with the remarks of Lutke
(volume ii., page 107, regarding Bigali) and of Freycinet ("Hydrog. Memoir
'L'Uranie' Voyage," page 188, regarding Tamatam, Ollap, etc.), it will be
seen that the artist must have represented the land incorrectly. The most
southern island in the group, namely PIGUIRAM, is not coloured, because I
have found no account of it. NOUGOUOR, or MONTE VERDISON, which was not
visited by Lutke, is described and figured by Mr. Bennett ("United Service
Journal," January 1832) as an atoll. All the above-mentioned islands have
been coloured blue.
WESTERN PART OF THE CAROLINE ARCHIPELAGO.
FAIS Island is ninety feet high, and is surrounded, as I have been informed
by Admiral Lutke, by a narrow reef of living coral, of which the broadest
part, as represented in the charts, is only 150 yards; coloured red.--
PHILIP Island., I believe, is low; but Hunter, in his "Historical Journal,"
gives no clear account of it; uncoloured.--ELIVI; from the manner in which
the islets on the reefs are engraved, in the "Atlas of the 'Astrolabe's'
Voyage," I should have thought they were above the ordinary height, but
Admiral Lutke assures me this is not the case: they form a regular atoll;
coloured blue.--GOUAP (EAP of Chamisso), is a high island with a reef (see
chart in "Voyage of the 'Astrolabe'"), more than a mile distant in most
parts from the shore, and two miles in one part. Captain D'Urville thinks
that there would be anchorage ("Hydrog. Descript. 'Astrolabe' Voyage," page
436) for ships within the reef, if a passage could be found; coloured pale
blue.--GOULOU, from the chart in the "'Astrolabe's' Atlas," appears to be
an atoll. D'Urville ("Hydrog. Descript." page 437) speaks of the low
islets on the reef; coloured dark blue.
Krusenstern speaks of some of the islands being mountainous; the reefs are
distant from the shore, and there are spaces within them, and not opposite
valleys, with from ten to fifteen fathoms. According to a MS. chart of the
group by Lieutenant Elmer in the Admiralty, there is a large space within
the reef with deepish water; although the high land does not hold a central
position with respect to the reefs, as is generally the case, I have little
doubt that the reefs of the Pelew Islands ought to be ranked with the
barrier class, and I have coloured them pale blue. In Lieutenant Elmer's
chart there is a horseshoe-formed shoal, laid down thirteen miles N.W. of
Pelew, with fifteen fathoms within the reef, and some dry banks on it;
coloured dark blue.--SPANISH, MARTIRES, SANSEROT, PULO ANNA and MARIERE
Islands are not coloured, because I know nothing about them, excepting that
according to Krusenstern, the second, third, and fourth mentioned, are low,
placed on coral-reefs, and therefore, perhaps, contain lagoons; but Pulo
Mariere is a little higher.
MARIANA ARCHIPELAGO, or LADRONES.
GUAHAN. Almost the whole of this island is fringed by reefs, which extend
in most parts about a third of a mile from the land. Even where the reefs
are most extensive, the water within them is shallow. In several parts
there is a navigable channel for boats and canoes within the reefs. In
Freycinet's "Hydrog. Mem." there is an account of these reefs, and in the
"Atlas," a map on a large scale; coloured red.--ROTA. "L'ile est presque
entierement entouree des recifs" (page 212, Freycinet's "Hydrog. Mem.").
These reefs project about a quarter of a mile from the shore; coloured
red.--TINIAN. THE EASTERN coast is precipitous, and is without reefs; but
the western side is fringed like the last island; coloured red.--SAYPAN.
The N.E. coast, and likewise the western shores appear to be fringed; but
there is a great, irregular, horn-like reef projecting far from this side;
coloured red.--FARALLON DE MEDINILLA, appears so regularly and closely
fringed in Freycinet's charts, that I have ventured to colour it red,
although nothing is said about reefs in the "Hydrographical Memoir." The
several islands which form the northern part of the group are volcanic
(with the exception perhaps of Torres, which resembles in form the
madreporitic island of Medinilla), and appear to be without reefs.--MANGS,
however, is described (by Freycinet, page 219, "Hydrog.") from some Spanish
charts, as formed of small islands placed "au milieu des nombreux recifs;"
and as these reefs in the general chart of the group do not project so much
as a mile; and as there is no appearance from a double line, of the
existence of deep water within, I have ventured, although with much
hesitation, to colour them red. Respecting FOLGER and MARSHALL Islands
which lie some way east of the Marianas, I can find out nothing, excepting
that they are probably low. Krusenstern says this of Marshall Island; and
Folger Island is written with small letters in D'Urville's chart;
BONIN OR ARZOBISPO GROUP.
PEEL Island has been examined by Captain Beechey, to whose kindness I am
much indebted for giving me information regarding it: "At Port Lloyd there
is a great deal of coral; and the inner harbour is entirely formed by
coral-reefs, which extend outside the port along the coast." Captain
Beechey, in another part of his letter to me, alludes to the reefs fringing
the island in all directions; but at the same time it must be observed that
the surf washes the volcanic rocks of the coast in the greater part of its
circumference. I do not know whether the other islands of the Archipelago
are fringed; I have coloured Peel Island red.--GRAMPUS Island to the
eastward, does not appear (Meare's "Voyage," page 95) to have any reefs,
nor does ROSARIO Island (from Lutke's chart), which lies to the westward.
Respecting the few other islands in this part of the sea, namely the
SULPHUR Islands, with an active volcano, and those lying between Bonin and
Japan (which are situated near the extreme limit in latitude, at which
reefs are formed), I have not been able to find any clear account.
WEST END OF NEW GUINEA.
PORT DORY. From the charts in the "Voyage of the 'Coquille'," it would
appear that the coast in this part is fringed by coral-reefs; M. Lesson,
however, remarks that the coral is sickly; coloured red.--WAIGIOU. A
considerable portion of the northern shores of these islands is seen in the
charts (on a large scale) in Freycinet's "Atlas" to be fringed by
coral-reefs. Forrest (page 21, "Voyage to New Guinea") alludes to the
coral-reefs lining the heads of Piapis Bay; and Horsburgh (volume ii., page
599, 4th edition), speaking of the islands in Dampier Strait, says "sharp
coral-rocks line their shores;" coloured red.--In the sea north of these
islands, we have GUEDES (or FREEWILL, or ST. DAVID'S), which from the chart
given in the 4to edition of Carteret's "Voyage," must be an atoll.
Krusenstern says the islets are very low; coloured blue.--CARTERET'S SHOALS,
in 2 deg 53' N., are described as circular, with stony points showing all
round, with deeper water in the middle; coloured blue.--AIOU; the plan of
this group, given in the "Atlas of the Voyage of the 'Astrolabe'," shows that
it is an atoll; and, from a chart in Forrest's "Voyage," it appears that
there is twelve fathoms within the circular reef; coloured blue.--The S.W.
coast of New Guinea appears to be low, muddy, and devoid of reefs. The ARRU,
TIMOR-LAUT, and TENIMBER groups have lately been examined by Captain Kolff,
the MS. translation of which, by Mr. W. Earl, I have been permitted to read,
through the kindness of Captain Washington, R.N. These islands are mostly
rather low, and are surrounded by distant reefs (the Ki Islands, however,
are lofty, and, from Mr. Stanley's survey, appear without reefs); the sea
in some parts is shallow, in others profoundly deep (as near Larrat). From
the imperfection of the published charts, I have been unable to decide to
which class these reefs belong. From the distance to which they extend
from the land, where the sea is very deep, I am strongly inclined to
believe they ought to come within the barrier class, and be coloured blue;
but I have been forced to leave them uncoloured.--The last-mentioned groups
are connected with the east end of Ceram by a chain of small islands, of
which the small groups of CERAM-LAUT, GORAM and KEFFING are surrounded by
very extensive reefs, projecting into deep water, which, as in the last
case, I strongly suspect belong to the barrier class; but I have not
coloured them. From the south side of Keffing, the reefs project five
miles (Windsor Earl's "Sailing Direct. for the Arafura Sea," page 9).
In various charts which I have examined, several parts of the coast are
represented as fringed by reefs.--MANIPA Island, between Ceram and Bourou,
in an old MS. chart in the Admiralty, is fringed by a very irregular reef,
partly dry at low water, which I do not doubt is of coral-formation; both
islands coloured red.--BOUROU; parts of this island appear fringed by
coral-reefs, namely, the eastern coast, as seen in Freycinet's chart; and
CAJELI BAY, which is said by Horsburgh (volume ii., page 630) to be lined
by coral-reefs, that stretch out a little way, and have only a few feet
water on them. In several charts, portions of the islands forming the
AMBOINA GROUP are fringed by reefs; for instance, NOESSA, HARENCA, and
UCASTER, in Freycinet's charts. The above-mentioned islands have been
coloured red, although the evidence is not very satisfactory.--North of
Bourou the parallel line of the XULLA Isles extends: I have not been able
to find out anything about them, excepting that Horsburgh (volume ii., page
543) says that the northern shore is surrounded by a reef at the distance
of two or three miles; uncoloured.--MYSOL GROUP; the Kanary Islands are
said by Forrest ("Voyage," page 130) to be divided from each other by deep
straits, and are lined with coral-rocks; coloured red.--GUEBE, lying
between Waigiou and Gilolo, is engraved as if fringed; and it is said by
Freycinet, that all the soundings under five fathoms were on coral;
coloured red.--GILOLO. In a chart published by Dalrymple, the numerous
islands on the western, southern (BATCHIAN and the STRAIT OF PATIENTIA),
and eastern sides appear fringed by narrow reefs; these reefs, I suppose,
are of coral, for it is said in "Malte Brun" (volume xii., page 156), "Sur
les cotes (of Batchian) comme DANS LES PLUPART des iles de cet archipel, il
y a de rocs de medrepores d'une beaute et d'une variete infimies."
Forrest, also (page 50), says Seland, near Batchian, is a little island
with reefs of coral; coloured red.--MORTY Island (north of Gilolo).
Horsburgh (volume ii., page 506) says the northern coast is lined by reefs,
projecting one or two miles, and having no soundings close to them; I have
left it uncoloured, although, as in some former cases, it ought probably to
be pale blue.--CELEBES. The western and northern coasts appear in the
charts to be bold and without reefs. Near the extreme northern point,
however, an islet in the STRAITS OF LIMBE, and parts of the adjoining
shore, appear to be fringed: the east side of the bay of MANADO, has deep
water, and is fringed by sand and coral ("'Astrol.' Voyage," Hydrog. Part,
pages 453-4); this extreme point, therefore, I have coloured red.--Of the
islands leading from this point to Magindanao, I have not been able to find
any account, except of SERANGANI, which appears surrounded by narrow reefs;
and Forrest ("Voyage," page 164) speaks of coral on its shores; I have,
therefore, coloured this island red. To the eastward of this chain lie
several islands; of which I cannot find any account, except of KARKALANG,
which is said by Horsburgh (volume ii., page 504) to be lined by a
dangerous reef, projecting several miles from the northern shore; not
ISLANDS NEAR TIMOR.
The account of the following islands is taken from Captain D. Kolff's
"Voyage," in 1825, translated by Mr. W. Earl, from the Dutch.--LETTE has
"reefs extending along shore at the distance of half a mile from the
land."--MOA has reefs on the S.W. part.--LAKOR has a reef lining its shore;
these islands are coloured red.--Still more eastward, LUAN has, differently
from the last-mentioned islands, an extensive reef; it is steep outside,
and within there is a depth of twelve feet; from these facts, it is
impossible to decide to which class this island belongs.--KISSA, off the
point of Timor, has its "shore fronted by a reef, steep too on the outer
side, over which small proahs can go at the time of high water;" coloured
red.--TIMOR; most of the points, and some considerable spaces of the
northern shore, are seen in Freycinet's chart to be fringed by coral-reefs;
and mention is made of them in the accompanying "Hydrog. Memoir;" coloured
red.--SAVU, S.E. of Timor, appears in Flinders' chart to be fringed; but I
have not coloured it, as I do not know that the reefs are of coral.--
SANDALWOOD Island has, according to Horsburgh (volume ii., page 607), a
reef on its southern shore, four miles distant from the land; as the
neighbouring sea is deep, and generally bold, this probably is a barrier-
reef, but I have not ventured to colour it.
N.W. COAST OF AUSTRALIA.
It appears, in Captain King's Sailing Directions ("Narrative of Survey,"
volume ii, pages 325-369), that there are many extensive coral-reefs
skirting, often at considerable distances, the N.W. shores, and
encompassing the small adjoining islets. Deep water, in no instance, is
represented in the charts between these reefs and the land; and, therefore,
they probably belong to the fringing class. But as they extend far into
the sea, which is generally shallow, even in places where the land seems to
be somewhat precipitous; I have not coloured them. Houtman's Abrolhos
(latitude 28 deg S. on west coast) have lately been surveyed by Captain
Wickham (as described in "Naut. Mag." 1841, page 511): they lie on the
edge of a steeply shelving bank, which extends about thirty miles seaward,
along the whole line of coast. The two southern reefs, or islands, enclose
a lagoon-like space of water, varying in depth from five to fifteen
fathoms, and in one spot with twenty-three fathoms. The greater part of
the island has been formed on their inland sides, by the accumulation of
fragments of coral; the seaward face consisting of nearly bare ledges of
rock. Some of the specimens, brought home by Captain Wickham, contained
fragments of marine shells, but others did not; and these closely resembled
a formation at King George's Sound, principally due to the action of the
wind on calcareous dust, which I shall describe in a forthcoming part.
From the extreme irregularity of these reefs with their lagoons, and from
their position on a bank, the usual depth of which is only thirty fathoms,
I have not ventured to class them with atolls, and hence have left them
uncoloured.--ROWLEY SHOALS. These lie some way from the N.W. coast of
Australia: according to Captain King ("Narrative of Survey," volume i.,
page 60), they are of coral-formation. They rise abruptly from the sea,
and Captain King had no bottom with 170 fathoms close to them. Three of
them are crescent-shaped; they are mentioned by Mr. Lyell, on the authority
of Captain King, with reference to the direction of their open sides. "A
third oval reef of the same group is entirely submerged" ("Principles of
Geology," book iii. chapter xviii.); coloured blue.--SCOTT'S REEFS, lying
north of Rowley Shoals, are briefly described by Captain Wickham ("Naut.
Mag." 1841, page 440): they appear to be of great size, of a circular
form, and "with smooth water within, forming probably a lagoon of great
extent." There is a break on the western side, where there probably is an
entrance: the water is very deep off these reefs; coloured blue.
Proceeding westward along the great volcanic chain of the East Indian
Archipelago, SOLOR STRAIT is represented in a chart published by Dalrymple
from a Dutch MS., as fringed; as are parts of FLORES, of ADENARA, and of
SOLOR. Horsburgh speaks of coral growing on these shores; and therefore I
have no doubt that the reefs are of coral, and accordingly have coloured
them red. We hear from Horsburgh (volume ii., page 602) that a coral-flat
bounds the shores of SAPY Bay. From the same authority it appears (page
610) that reefs fringe the island of TIMOR-YOUNG, on the N. shore of
Sumbawa; and, likewise (page 600), that BALLY town in LOMBOCK, is fronted
by a reef, stretching along the shore at a distance of a hundred fathoms,
with channels through it for boats; these places, therefore, have been
coloured red.--BALLY Island. In a Dutch MS. chart on a large scale of
Java, which was brought from that island by Dr. Horsfield, who had the
kindness to show it me at the India House, its western, northern, and
southern shores appear very regularly fringed by a reef (see also
Horsburgh, volume ii., page 593); and as coral is found abundantly there, I
have not the least doubt that the reef is of coral, and therefore have
coloured it red.
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.
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.
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.
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.
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.
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.
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'."
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.
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
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.
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.
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.
My information is chiefly derived from the admirable charts published by
the East India Company in 1836, from personal communication with Captain
Moresby, one of the surveyors, and from the excellent memoir, "Uber die
Natur der Corallen-Banken des Rothen Meeres," by Ehrenberg. The plains
immediately bordering the Red Sea seem chiefly to consist of a sedimentary
formation of the newer tertiary period. The shore is, with the exception
of a few parts, fringed by coral-reefs. The water is generally profoundly
deep close to the shore; but this fact, which has attracted the attention
of most voyagers, seems to have no necessary connection with the presence
of reefs; for Captain Moresby particularly observed to me, that, in
latitude 24 deg 10' on the eastern side, there is a piece of coast, with
very deep water close to it, without any reefs, but not differing in other
respects from the usual nature of the coast-line. The most remarkable
feature in the Red Sea is the chain of submerged banks, reefs, and islands,
lying some way from the shore, chiefly on the eastern side; the space
within being deep enough to admit a safe navigation in small vessels. The
banks are generally of an oval form, and some miles in width; but some of
them are very long in proportion to their width. Captain Moresby informs
me that any one, who had not made actual plans of them, would be apt to
think that they were much more elongated than they really are. Many of
them rise to the surface, but the greater number lie from five to thirty
fathoms beneath it, with irregular soundings on them. They consist of sand
and living coral; coral on most of them, according to Captain Moresby,
covering the greater part of their surface. They extend parallel to the
shore, and they are not unfrequently connected in their middle parts by
short transverse banks with the mainland. The sea is generally profoundly
deep quite close to them, as it is near most parts of the coast of the
mainland; but this is not universally the case, for between latitude 15 deg
and 17 deg the water deepens quite gradually from the banks, both on the
eastern and western shores, towards the middle of the sea. Islands in many
parts arise from these banks; they are low, flat-topped, and consist of the
same horizontally stratified formation with that forming the plain-like
margin of the mainland. Some of the smaller and lower islands consist of
mere sand. Captain Moresby informs me, that small masses of rock, the
remnants of islands, are left on many banks where there is now no dry land.
Ehrenberg also asserts that most of the islets, even the lowest, have a
flat abraded basis, composed of the same tertiary formation: he believes
that as soon as the surf wears down the protuberant parts of a bank, just
beneath the level of the sea, the surface becomes protected from further
abrasion by the growth of coral, and he thus accounts for the existence of
so many banks standing on a level with the surface of this sea. It appears
that most of the islands are certainly decreasing in size.
The form of the banks and islands is most singular in the part just
referred to, namely, from latitude 15 deg to 17 deg, where the sea deepens
quite gradually: the DHALAC group, on the western coast, is surrounded by
an intricate archipelago of islets and shoals; the main island is very
irregularly shaped, and it includes a bay seven miles long, by four across,
in which no bottom was found with 252 feet: there is only one entrance
into this bay, half a mile wide, and with an island in front of it. The
submerged banks on the eastern coast, within the same latitudes, round
FARSAN Island, are, likewise, penetrated by many narrow creeks of deep
water; one is twelve miles long, in the form of a hatchet, in which, close
to its broad upper end, soundings were not struck with 360 feet, and its
entrance is only half a mile wide: in another creek of the same nature,
but even with a more irregular outline, there was no bottom with 480 feet.
The island of Farsan, itself, has as singular a form as any of its
surrounding banks. The bottom of the sea round the Dhalac and Farsan
Islands consists chiefly of sand and agglutinated fragments, but, in the
deep and narrow creeks, it consists of mud; the islands themselves consist
of thin, horizontally stratified, modern tertiary beds, containing but
little broken coral (Ruppell, "Reise in Abyssinie," Band. i., S. 247.),
their shores are fringed by living coral-reefs.
From the account given by Ruppell (Ibid., S. 245.) of the manner in which
Dhalac has been rent by fissures, the opposite sides of which have been
unequally elevated (in one instance to the amount of fifty feet), it seems
probable that its irregular form, as well as probably that of Farsan, may
have been partly caused by unequal elevations; but, considering the general
form of the banks, and of the deep-water creeks, together with the
composition of the land, I think their configuration is more probably due
in great part to strong currents having drifted sediment over an uneven
bottom: it is almost certain that their form cannot be attributed to the
growth of coral. Whatever may have been the precise origin of the Dhalac
and Farsan Archipelagoes, the greater number of the banks on the eastern
side of the Red Sea seem to have originated through nearly similar means.
I judge of this from their similarity in configuration (in proof of which I
may instance a bank on the east coast in latitude 22 deg; and although it
is true that the northern banks generally have a less complicated outline),
and from their similarity in composition, as may be observed in their
upraised portions. The depth within the banks northward of latitude 17
deg, is usually greater, and their outer sides shelve more abruptly
(circumstances which seem to go together) than in the Dhalac and Farsan
Archipelagoes; but this might easily have been caused by a difference in
the action of the currents during their formation: moreover, the greater
quantity of living coral, which, according to Captain Moresby, exists on
the northern banks, would tend to give them steeper margins.
From this account, brief and imperfect as it is, we can see that the great
chain of banks on the eastern coast, and on the western side in the
southern portion, differ greatly from true barrier-reefs wholly formed by
the growth of coral. It is indeed the direct conclusion of Ehrenberg
("Uber die," etc., pages 45 and 51), that they are connected in their
origin quite secondarily with the growth of coral; and he remarks that the
islands off the coast of Norway, if worn down level with the sea, and
merely coated with living coral, would present a nearly similar appearance.
I cannot, however, avoid suspecting, from information given me by Dr.
Malcolmson and Captain Moresby, that Ehrenberg has rather under-rated the
influence of corals, in some places at least, on the formation of the
tertiary deposits of the Red Sea.
THE WEST COAST OF THE RED SEA BETWEEN LATITUDE 19 DEG AND 22 DEG.
There are, in this space, reefs, which, if I had known nothing of those in
other parts of the Red Sea, I should unhesitatingly have considered as
barrier-reefs; and, after deliberation, I have come to the same conclusion.
One of these reefs, in 20 deg 15', is twenty miles long, less than a mile
in width (but expanding at the northern end into a disc), slightly sinuous,
and extending parallel to the mainland at the distance of five miles from
it, with very deep water within; in one spot soundings were not obtained
with 205 fathoms. Some leagues further south, there is another linear
reef, very narrow, ten miles long, with other small portions of reef, north
and south, almost connected with it; and within this line of reefs (as well
as outside) the water is profoundly deep. There are also some small linear
and sickle-formed reefs, lying a little way out at sea. All these reefs
are covered, as I am informed by Captain Moresby, by living corals. Here,
then, we have all the characters of reefs of the barrier class; and in some
outlying reefs we have an approach to the structure of atolls. The source
of my doubts about the classification of these reefs, arises from having
observed in the Dhalac and Farsan groups the narrowness and straightness of
several spits of sand and rock: one of these spits in the Dhalac group is
nearly fifteen miles long, only two broad, and it is bordered on each side
with deep water; so that, if worn down by the surf, and coated with living
corals, it would form a reef nearly similar to those within the space under
consideration. There is, also, in this space (latitude 21 deg) a
peninsula, bordered by cliffs, with its extremity worn down to the level of
the sea, and its basis fringed with reefs: in the line of prolongation of
this peninsula, there lies the island of MACOWA (formed, according to
Captain Moresby, of the usual tertiary deposit), and some smaller islands,
large parts of which likewise appear to have been worn down, and are now
coated with living corals. If the removal of the strata in these several
cases had been more complete, the reefs thus formed would have nearly
resembled those barrier-like ones now under discussion. Notwithstanding
these facts, I cannot persuade myself that the many very small, isolated,
and sickle-formed reefs and others, long, nearly straight, and very narrow,
with the water unfathomably deep close round them, could possibly have been
formed by corals merely coating banks of sediment, or the abraded surfaces
of irregularly shaped islands. I feel compelled to believe that the
foundations of these reefs have subsided, and that the corals, during their
upward growth, have given to these reefs their present forms: I may remark
that the subsidence of narrow and irregularly-shaped peninsulas and
islands, such as those existing on the coasts of the Red Sea, would afford
the requisite foundations for the reefs in question.
THE WEST COAST FROM LATITUDE 22 DEG TO 24 DEG.
This part of the coast (north of the space coloured blue on the map) is
fronted by an irregularly shelving bank, from about ten to thirty fathoms
deep; numerous little reefs, some of which have the most singular shapes,
rise from this bank. It may be observed, respecting one of them, in
latitude 23 deg 10', that if the promontory in latitude 24 deg were worn
down to the level of the sea, and coated with corals, a very similar and
grotesquely formed reef would be produced. Many of the reefs on this part
of the coast may thus have originated; but there are some sickle, and
almost atoll-formed reefs lying in deep water off the promontory in
latitude 24 deg, which lead me to suppose that all these reefs are more
probably allied to the barrier or atoll classes. I have not, however,
ventured to colour this portion of coast. ON THE WEST COAST FROM LATITUDE
19 DEG TO 17 DEG (south of space coloured blue on the map), there are many
low islets of very small dimensions, not much elongated, and rising out of
great depths at a distance from the coast; these cannot be classed either
with atolls, or barrier- or fringing-reefs. I may here remark that the
outlying reefs on the west coast, between latitude 19 deg and 24 deg, are
the only ones in the Red Sea, which approach in structure to the true
atolls of the Indian and Pacific Oceans, but they present only imperfect
miniature likenesses of them.
I have felt the greatest doubt about colouring any portion of this coast,
north of the fringing-reefs round the Farsan Islands in 16 deg 10'. There
are many small outlying coral-reefs along the whole line of coast; but as
the greater number rise from banks not very deeply submerged (the formation
of which has been shown to be only secondarily connected with the growth of
coral), their origin may be due simply to the growth of knolls of corals,
from an irregular foundation situated within a limited depth. But between
latitude 18 deg and 20 deg, there are so many linear, elliptic, and
extremely small reefs, rising abruptly out of profound depths, that the
same reasons, which led me to colour blue a portion of the west coast, have
induced me to do the same in this part. There exist some small outlying
reefs rising from deep water, north of latitude 20 deg (the northern limit
coloured blue), on the east coast; but as they are not very numerous and
scarcely any of them linear, I have thought it right to leave them
In the SOUTHERN PARTS of the Red Sea, considerable spaces of the mainland,
and of some of the Dhalac islands, are skirted by reefs, which, as I am
informed by Captain Moresby, are of living coral, and have all the
characters of the fringing class. As in these latitudes, there are no
outlying linear or sickle-formed reefs, rising out of unfathomable depths,
I have coloured these parts of the coast red. On similar grounds, I have
coloured red the NORTHERN PARTS OF THE WESTERN COAST (north of latitude 24
deg 30'), and likewise the shores of the chief part of the GULF OF SUEZ.
In the GULF OF ACABA, as I am informed by Captain Moresby there are no
coral-reefs, and the water is profoundly deep.
My information regarding the reefs of this area, is derived from various
sources, and from an examination of numerous charts; especially of those
lately executed during the survey under Captain Owen, R.N. I lay under
particular obligation to Captain Bird Allen, R.N., one of the members of
the late survey, for many personal communications on this subject. As in
the case of the Red Sea, it is necessary to make some preliminary remarks
on the submerged banks of the West Indies, which are in some degree
connected with coral-reefs, and cause considerable doubts in their
classification. That large accumulations of sediment are in progress on
the West Indian shores, will be evident to any one who examines the charts
of that sea, especially of the portion north of a line joining Yucutan and
Florida. The area of deposition seems less intimately connected with the
debouchement of the great rivers, than with the course of the sea-currents;
as is evident from the vast extension of the banks from the promontories of
Yucutan and Mosquito.
Besides the coast-banks, there are many of various dimensions which stand
quite isolated; these closely resemble each other, they lie from two or
three to twenty or thirty fathoms under water, and are composed of sand,
sometimes firmly agglutinated, with little or no coral; their surfaces are
smooth and nearly level, shelving only to the amount of a few fathoms, very
gradually all round towards their edges, where they plunge abruptly into
the unfathomable sea. This steep inclination of their sides, which is
likewise characteristic of the coast-banks, is very remarkable: I may give
as an instance, the Misteriosa Bank, on the edges of which the soundings
change in 250 fathoms horizontal distance, from 11 to 210 fathoms; off the
northern point of the bank of Old Providence, in 200 fathoms horizontal
distance, the change is from 19 to 152 fathoms; off the Great Bahama Bank,
in 160 fathoms horizontal distance, the inclination is in many places from
10 fathoms to no bottom with 190 fathoms. On coasts in all parts of the
world, where sediment is accumulating, something of this kind may be
observed; the banks shelve very gently far out to sea, and then terminate
abruptly. The form and composition of the banks standing in the middle
parts of the W. Indian Sea, clearly show that their origin must be chiefly
attributed to the accumulation of sediment; and the only obvious
explanation of their isolated position is the presence of a nucleus, round
which the currents have collected fine drift matter. Any one who will
compare the character of the bank surrounding the hilly island of Old
Providence, with those banks in its neighbourhood which stand isolated,
will scarcely doubt that they surround submerged mountains. We are led to
the same conclusion by examining the bank called Thunder Knoll, which is
separated from the Great Mosquito Bank by a channel only seven miles wide,
and 145 fathoms deep. There cannot be any doubt that the Mosquito Bank has
been formed by the accumulation of sediment round the promontory of the
same name; and Thunder Knoll resembles the Mosquito Bank, in the state of
its surface submerged twenty fathoms, in the inclinations of its sides, in
composition, and in every other respect. I may observe, although the
remark is here irrelevant, that geologists should be cautious in concluding
that all the outlyers of any formation have once been connected together,
for we here see that deposits, doubtless of exactly the same nature, may be
deposited with large valley-like spaces between them.
Linear strips of coral-reefs and small knolls project from many of the
isolated, as well as coast-banks; sometimes they occur quite irregularly
placed, as on the Mosquito Bank, but more generally they form crescents on
the windward side, situated some little distance within the outer edge of
the banks:--thus on the Serranilla Bank they form an interrupted chain
which ranges between two and three miles within the windward margin:
generally they occur, as on Roncador, Courtown, and Anegada Banks, nearer
the line of deep water. Their occurrence on the windward side is
conformable to the general rule, of the efficient kinds of corals
flourishing best where most exposed; but their position some way within the
line of deep water I cannot explain, without it be, that a depth somewhat
less than that close to the outer margin of the banks, is most favourable
to their growth. Where the corals have formed a nearly continuous rim,
close to the windward edge of a bank some fathoms submerged, the reef
closely resembles an atoll; but if the bank surrounds an island (as in the
case of Old Providence), the reef resembles an encircling barrier-reef. I
should undoubtedly have classed some of these fringed banks as imperfect
atolls, or barrier-reefs, if the sedimentary nature of their foundations
had not been evident from the presence of other neighbouring banks, of
similar forms and of similar composition, but without the crescent-like
marginal reef: in the third chapter, I observed that probably some atoll-like
reefs did exist, which had originated in the manner here supposed.
Proofs of elevation within recent tertiary periods abound, as referred to
in the sixth chapter, over nearly the whole area of the West Indies. Hence
it is easy to understand the origin of the low land on the coasts, where
sediment is now accumulating; for instance on the northern part of Yucutan,
and on the N.E. part of Mosquito, where the land is low, and where
extensive banks appear to be in progressive formation. Hence, also, the
origin of the Great Bahama Banks, which are bordered on their western and
southern edges by very narrow, long, singularly shaped islands, formed of
sand, shells, and coral-rock, and some of them about a hundred feet in
height, is easily explained by the elevation of banks fringed on their
windward (western and southern) sides by coral-reefs. On this view,
however, we must suppose either that the chief part of the surfaces of the
great Bahama sandbanks were all originally deeply submerged, and were
brought up to their present level by the same elevatory action, which
formed the linear islands; or that during the elevation of the banks, the
superficial currents and swell of the waves continued wearing them down and
keeping them at a nearly uniform level: the level is not quite uniform;
for, in proceeding from the N.W. end of the Bahama group towards the S.E.
end, the depth of the banks increases, and the area of land decreases, in a
very gradual and remarkable manner. The latter view, namely, that these
banks have been worn down by the currents and swell during their elevation,
seems to me the most probable one. It is, also, I believe, applicable to
many banks, situated in widely distant parts of the West Indian Sea, which
are wholly submerged; for, on any other view, we must suppose, that the
elevatory forces have acted with astonishing uniformity.
The shores of the Gulf of Mexico, for the space of many hundred miles, is
formed by a chain of lagoons, from one to twenty miles in breadth
("Columbian Navigator," page 178, etc.), containing either fresh or salt
water, and separated from the sea by linear strips of sand. Great spaces
of the shores of Southern Brazil (In the "London and Edinburgh
Philosophical Journal," 1841, page 257, I have described a singular bar of
sandstone lying parallel to the coast off Pernambuco in Brazil, which
probably is an analogous formation.), and of the United States from Long
Island (as observed by Professor Rogers) to Florida have the same
character. Professor Rogers, in his "Report to the British Association"
(volume iii., page 13), speculates on the origin of these low, sandy,
linear islets; he states that the layers of which they are composed are too
homogeneous, and contain too large a proportion of shells, to permit the
common supposition of their formation being simply due to matter thrown up,
where it now lies, by the surf: he considers these islands as upheaved
bars or shoals, which were deposited in lines where opposed currents met.
It is evident that these islands and spits of sand parallel to the coast,
and separated from it by shallow lagoons, have no necessary connection with
coral-formations. But in Southern Florida, from the accounts I have
received from persons who have resided there, the upraised islands seem to
be formed of strata, containing a good deal of coral, and they are
extensively fringed by living reefs; the channels within these islands are
in some places between two and three miles wide, and five or six fathoms
deep, though generally (In the ordinary sea-charts, no lagoons appear on
the coast of Florida, north of 26 deg; but Major Whiting ("Silliman's
Journal," volume xxxv., page 54) says that many are formed by sand thrown
up along the whole line of coast from St. Augustine's to Jupiter Inlet.)
they are less in depth than width. After having seen how frequently banks
of sediment in the West Indian Sea are fringed by reefs, we can readily
conceive that bars of sediment might be greatly aided in their formation
along a line of coast, by the growth of corals; and such bars would, in
that case, have a deceptive resemblance with true barrier-reefs.
Having now endeavoured to remove some sources of doubt in classifying the
reefs of the West Indies, I will give my authorities for colouring such
portions of the coast as I have thought myself warranted in doing. Captain
Bird Allen informs me, that most of the islands on the BAHAMA BANKS are
fringed, especially on their windward sides, with living reefs; and hence I
have coloured those, which are thus represented in Captain Owen's late
chart, red. The same officer informs me, that the islands along the
southern part of FLORIDA are similarly fringed; coloured red. CUBA:
Proceeding along the northern coast, at the distance of forty miles from
the extreme S.E. point, the shores are fringed by reefs, which extend
westward for a space of 160 miles, with only a few breaks. Parts of these
reefs are represented in the plans of the harbours on this coast by Captain
Owen; and an excellent description is given of them by Mr. Taylor (Loudon's
"Mag. of Nat. Hist." volume ix., page 449); he states that they enclosed a
space called the "baxo," from half to three-quarters of a mile in width,
with a sandy bottom, and a little coral. In most parts people can wade, at
low water, to the reef; but in some parts the depth is between two and
three fathoms. Close outside the reef, the depth is between six and seven
fathoms; these well-characterised fringing-reefs are coloured red.
Westward of longitude 77 deg 30', on the northern side of Cuba, a great
bank commences, which extends along the coast for nearly four degrees of
longitude. In the place of its commencement, in its structure, and in the
"CAYS," or low islands on its edge, there is a marked correspondence (as
observed by Humboldt, "Pers. Narr." volume vii., page 88) between it and
the Great Bahama and Sal Banks, which lie directly in front. Hence one is
led to attribute the same origin to both these sets of banks; namely, the
accumulation of sediment, conjoined with an elevatory movement, and the
growth of coral on their outward edges; those parts which appear fringed by
living reefs are coloured red. Westward of these banks, there is a portion
of coast apparently without reefs, except in the harbours, the shores of
which seem in the published plans to be fringed. The COLORADO SHOALS (see
Captain Owen's charts), and the low land at the western end of Cuba,
correspond as closely in relative position and structure to the banks at
the extreme point of Florida, as the banks above described on the north
side of Cuba, do to the Bahamas, the depth within the islets and reefs on
the outer edge of the COLORADOS, is generally between two and three
fathoms, increasing to twelve fathoms in the southern part, where the bank
becomes nearly open, without islets or coral-reefs; the portions which are
fringed are coloured red. The southern shore of Cuba is deeply concave,
and the included space is filled up with mud and sandbanks, low islands and
coral-reefs. Between the mountainous ISLE OF PINES and the southern shore
of Cuba, the general depth is only between two and three fathoms; and in
this part small islands, formed of fragmentary rock and broken madrepores
(Humboldt, "Pers. Narr." volume vii. pages 51, 86 to 90, 291, 309, 320),
rise abruptly, and just reach the surface of the sea. From some
expressions used in the "Columbian Navigator" (volume i., part ii., page
94), it appears that considerable spaces along the outer coast of Southern
Cuba are bounded by cliffs of coral-rock, formed probably by the upheaval
of coral-reefs and sandbanks. The charts represent the southern part of
the Isle of Pines as fringed by reefs, which the "Columb. Navig." says
extend some way from the coast, but have only from nine to twelve feet
water on them; these are coloured red.--I have not been able to procure any
detailed description of the large groups of banks and "cays" further
eastward on the southern side of Cuba; within them there is a large
expanse, with a muddy bottom, from eight to twelve fathoms deep; although
some parts of this line of coast are represented in the general charts of
the West Indies, as fringed, I have not thought it prudent to colour them.
The remaining portion of the south coast of Cuba appears to be without
The N.E. part of the promontory appears in Captain Owen's charts to be
fringed; coloured red. The eastern coast, from 20 deg to 18 deg is
fringed. South of latitude 18 deg, there commences the most remarkable
reef in the West Indies: it is about one hundred and thirty miles in
length, ranging in a N. and S. line, at an average distance of fifteen
miles from the coast. The islets on it are all low, as I have been
informed by Captain B. Allen; the water deepens suddenly on the outside of
the reef, but not more abruptly than off many of the sedimentary banks:
within its southern extremity (off HONDURAS) the depth is twenty-five
fathoms; but in the more northern parts, the depth soon increases to ten
fathoms, and within the northernmost part, for a space of twenty miles, the
depth is only from one to two fathoms. In most of these respects we have
the characteristics of a barrier-reef; nevertheless, from observing, first,
that the channel within the reef is a continuation of a great irregular
bay, which penetrates the mainland to the depth of fifty miles; and
secondly, that considerable spaces of this barrier-like reef are described
in the charts (for instance, in latitude 16 deg 45' and 16 deg 12') as
formed of pure sand; and thirdly, from knowing that sediment is
accumulating in many parts of the West Indies in banks parallel to the
shore; I have not ventured to colour this reef as a barrier, without
further evidence that it has really been formed by the growth of corals,
and that it is not merely in parts a spit of sand, and in other parts a
worn down promontory, partially coated and fringed by reefs; I lean,
however, to the probability of its being a barrier-reef, produced by
subsidence. To add to my doubts, immediately on the outside of this
barrier-like reef, TURNEFFE, LIGHTHOUSE, and GLOVER reefs are situated, and
these reefs have so completely the form of atolls, that if they had
occurred in the Pacific, I should not have hesitated about colouring them
blue. TURNEFFE REEF seems almost entirely filled up with low mud islets;
and the depth within the other two reefs is only from one to three fathoms.
From this circumstance and from their similarity in form, structure, and
relative position, both to the bank called NORTHERN TRIANGLES, on which
there is an islet between seventy and eighty feet, and to COZUMEL Island,
the level surface of which is likewise between seventy and eighty feet in
height, I consider it more probable that the three foregoing banks are the
worn down bases of upheaved shoals, fringed with corals, than that they are
true atolls, wholly produced by the growth of coral during subsidence; left
In front of the eastern MOSQUITO coast, there are between latitude 12 deg
and 16 deg some extensive banks (already mentioned, page 148), with high
islands rising from their centres; and there are other banks wholly
submerged, both of which kinds of banks are bordered, near their windward
margins, by crescent-shaped coral-reefs. But it can hardly be doubted, as
was observed in the preliminary remarks, that these banks owe their origin,
like the great bank extending from the Mosquito promontory, almost entirely
to the accumulation of sediment, and not to the growth of corals; hence I
have not coloured them.
CAYMAN ISLAND: this island appears in the charts to be fringed; and
Captain B. Allen informs me that the reefs extend about a mile from the
shore, and have only from five to twelve feet water within them; coloured
red.--JAMAICA: judging from the charts, about fifteen miles of the S.E.
extremity, and about twice that length on the S.W. extremity, and some
portions on the S. side near Kingston and Port Royal, are regularly
fringed, and therefore are coloured red. From the plans of some harbours
on the N. side of Jamaica, parts of the coast appear to be fringed; but as
these are not represented in the charts of the whole island, I have not
coloured them.--ST. DOMINGO: I have not been able to obtain sufficient
information, either from plans of the harbours, or from general charts, to
enable me to colour any part of the coast, except sixty miles from Port de
Plata westward, which seems very regularly fringed; many other parts,
however, of the coast are probably fringed, especially towards the eastern
end of the island.--PUERTO RICO: considerable portions of the southern,
western, and eastern coasts, and some parts of the northern coast, appear
in the charts to be fringed; coloured red.--Some miles in length of the
southern side of the Island of ST. THOMAS is fringed; most of the VIRGIN
GORDA Islands, as I am informed by Mr. Schomburgk, are fringed; the shores
of ANEGADA, as well as the bank on which it stands, are likewise fringed;
these islands have been coloured red. The greater part of the southern
side of SANTA CRUZ appears in the Danish survey to be fringed (see also
Prof. Hovey's account of this island, in "Silliman's Journal," volume
xxxv., page 74); the reefs extend along the shore for a considerable space,
and project rather more than a mile; the depth within the reef is three
fathoms; coloured red.--The ANTILLES, as remarked by Von Buch ("Descrip.
Iles Canaries," page 494), may be divided into two linear groups, the
western row being volcanic, and the eastern of modern calcareous origin; my
information is very defective on the whole group. Of the eastern islands,
BARBUDA and the western coasts of ANTIGUA and MARIAGALANTE appear to be
fringed: this is also the case with BARBADOES, as I have been informed by
a resident; these islands are coloured red. On the shores of the Western
Antilles, of volcanic origin, very few coral-reefs appear to exist. The
island of MARTINIQUE, of which there are beautifully executed French
charts, on a very large scale, alone presents any appearance worthy of
special notice. The south-western, southern, and eastern coasts, together
forming about half the circumference of the island, are skirted by very
irregular banks, projecting generally rather less than a mile from the
shore, and lying from two to five fathoms submerged. In front of almost
every valley, they are breached by narrow, crooked, steep-sided passages.
The French engineers ascertained by boring, that these submerged banks
consisted of madreporitic rocks, which were covered in many parts by thin
layers of mud or sand. From this fact, and especially from the structure
of the narrow breaches, I think there can be little doubt that these banks
once formed living reefs, which fringed the shores of the island, and like
other reefs probably reached the surface. From some of these submerged
banks reefs of living coral rise abruptly, either in small detached
patches, or in lines parallel to, but some way within the outer edges of
the banks on which they are based. Besides the above banks which skirt the
shores of the island, there is on the eastern side a range of linear banks,
similarly constituted, twenty miles in length, extending parallel to the
coast line, and separated from it by a space between two and four miles in
width, and from five to fifteen fathoms in depth. From this range of
detached banks, some linear reefs of living coral likewise rise abruptly;
and if they had been of greater length (for they do not front more than a
sixth part of the circumference of the island), they would necessarily from
their position have been coloured as barrier-reefs; as the case stands they
are left uncoloured. I suspect that after a small amount of subsidence,
the corals were killed by sand and mud being deposited on them, and the
reefs being thus prevented from growing upwards, the banks of madreporitic
rock were left in their present submerged condition.
THE BERMUDA Islands have been carefully described by Lieutenant Nelson, in
an excellent Memoir in the "Geological Transactions" (volume v., part i.,
page 103). In the form of the bank or reef, on one side of which the
islands stand, there is a close general resemblance to an atoll; but in the
following respects there is a considerable difference,--first, in the
margin of the reef not forming (as I have been informed by Mr. Chaffers,
R.N.) a flat, solid surface, laid bare at low water, and regularly bounding
the internal space of shallow water or lagoon; secondly, in the border of
gradually shoaling water, nearly a mile and a half in width, which
surrounds the entire outside of the reef (as is laid down in Captain Hurd's
chart); and thirdly, in the size, height, and extraordinary form of the
islands, which present little resemblance to the long, narrow, simple
islets, seldom exceeding half a mile in breadth, which surmount the annular
reefs of almost all the atolls in the Indian and Pacific Oceans. Moreover,
there are evident proofs (Nelson, Ibid., page 118), that islands similar to
the existing ones, formerly extended over other parts of the reef. It
would, I believe, be difficult to find a true atoll with land exceeding
thirty feet in height; whereas, Mr. Nelson estimates the highest point of
the Bermuda Islands to be 260 feet; if, however, Mr. Nelson's view, that
the whole of the land consists of sand drifted by the winds, and
agglutinated together, were proved correct, this difference would be
immaterial; but, from his own account (page 118), there occur in one place,
five or six layers of red earth, interstratified with the ordinary
calcareous rock, and including stones too heavy for the wind to have moved,
without having at the same time utterly dispersed every grain of the
accompanying drifted matter. Mr. Nelson attributes the origin of these
several layers, with their embedded stones, to as many violent
catastrophes; but further investigation in such cases has generally
succeeded in explaining phenomena of this kind by ordinary and simpler
means. Finally, I may remark, that these islands have a considerable
resemblance in shape to Barbuda in the West Indies, and to Pemba on the
eastern coast of Africa, which latter island is about two hundred feet in
height, and consists of coral-rock. I believe that the Bermuda Islands,
from being fringed by living reefs, ought to have been coloured red; but I
have left them uncoloured, on account of their general resemblance in
external form to a lagoon-island or atoll.
The names not in capitals are all names of places, and refer exclusively to
the Appendix: in well-defined archipelagoes, or groups of islands, the
name of each separate island is not given.
ABROLHOS, Brazil, coated by corals.
ABSENCE of coral-reefs from certain coasts.
Acaba, gulf of.
AFRICA, east coast, fringing-reef of.
Madreporitic rock of.
Africa, east coast.
AGE of individual corals.
Alexander, Grand Duke, island.
ALLAN, Dr., on Holuthuriae feeding on corals.
On quick growth of corals at Madagascar.
On reefs affected by currents.
America, west coast.
ANAMOUKA, description of.
AREAS, great extent of, interspersed with low islands.
Of subsidence and of elevation.
Of subsidence appear to be elongated.
Of subsidence alternating with areas of elevation.
ASCIDIA, depth at which found.
ATOLLS, breaches in their reefs.
Dimensions of groups of.
Not based on craters or on banks of sediment, or of rock.
Of irregular forms.
Steepness of their flanks.
Width of their reef and islets.
With part of their reef submerged, and theory of.
AURORA island, an upraised atoll.
AUSTRAL islands, recently elevated.
Australia, N.W. coast.
BARRIER-REEF of Australia.
Of New Caledonia.
BARRIER-REEFS, breaches through.
Not based on worn down margin of rock.
On banks of sediment.
On submarine craters.
Steepness of their flanks.
Their probable vertical thickness.
Theory of their formation.
Banks in the West Indies.
BEECHEY, Captain, obligations of the author to.
On submerged reefs.
Account of Matilda island.
BELCHER, Captain, on boring through coral-reef.
Belize reef, off.
BOLABOLA, view of.
BORINGS through coral-reefs.
BORNEO, W. coast, recently elevated.
Borneo, E. coast.
S.W. and W. coast
BRAZIL, fringing-reefs on coast of.
BREACHES through barrier-reefs.
CARYOPHYLLIA, depth at which it lives.
CEYLON, recently elevated.
CHAGOS Great Bank, description and theory of.
CHAMA-SHELLS embedded in coral-rock.
CHAMISSO, on corals preferring the surf.
CHANGES in the state of Keeling atoll.
CHANNELS leading into the lagoons of atolls.
Into the Maldiva atolls.
Christmas island (Indian Ocean).
COCOS, or Keeling atoll.
Cocos (or Keeling).
Cocos island (Pacific).
COCHIN China, encroachments of the sea on the coast.
COMPOSITION of coral-formations.
CONGLOMERATE coral-rock on Keeling atoll.
On other atolls.
COOK islands, recently elevated.
CORAL-BLOCKS bored by vermiform animals.
CORAL-REEFS, their distribution and absence from certain areas.
Destroyed by loose sediment.
CORAL-ROCK at Keeling atoll.
Organic remains of.
CORALS dead but upright in Keeling lagoon.
Depths at which they live.
Off Keeling atoll.
Killed by a short exposure.
Living in the lagoon of Keeling atoll.
Quick growth of, in Keeling lagoon.
Merely coating the bottom of the sea.
Standing exposed in the Low archipelago.
COUTHOUY, Mr., alleged proofs of recent elevation of the Low archipelago.
On coral-rock at Mangaia and Aurora islands.
On external ledges round coral-islands.
Remarks confirmatory of the author's theory.
CUMING, Mr., on the recent elevation of the Philippines.
Dangerous, or Low archipelago.
DEPTHS at which reef-building corals live.
At Mauritius, the Red Sea, and in the Maldiva archipelago.
At which other corals and corallines can live.
DIEGO GARCIA, slow growth of reef.
DIMENSIONS of the larger groups of atolls.
DISSEVERMENT of the Maldiva atolls, and theory of.
DISTRIBUTION of coral-reefs.
DORY, Port, recently elevated.
EARTHQUAKES at Keeling atoll.
In groups of atolls.
In Navigator archipelago.
EAST INDIAN ARCHIPELAGO, recently elevated.
EHRENBERG, on the banks of the Red Sea.
On depths at which corals live in the Red Sea.
On corals preferring the surf.
On the antiquity of certain corals.
ELEVATED reef of Mauritius.
ELEVATIONS, recent proofs of.
Immense areas of.
ENCIRCLED ISLANDS, their height.
EOUA, description of.
ERUPTED MATTER probably not associated with thick masses of coral-rock.
FAIS, recently elevated.
Farallon de Medinilla.
FISH, feeding on corals.
Killed in Keeling lagoon by heavy rain.
FISSURES across coral-islands.
FITZROY, Captain, on a submerged shed at Keeling atoll.
On an inundation in the Low archipelago.
FORSTER, theory of coral-formations.