Part 9 (2/2)

Coral Reefs Charles Darwin 146660K 2022-07-22

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 sh.o.r.e 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 sh.o.r.e, 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 sh.o.r.es; 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 sh.o.r.e; not coloured.

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 sh.o.r.e at the distance of half a mile from the land.”--MOA has reefs on the S.W. part.--LAKOR has a reef lining its sh.o.r.e; 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 cla.s.s this island belongs.--KISSA, off the point of Timor, has its ”sh.o.r.e 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 s.p.a.ces of the northern sh.o.r.e, 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 sh.o.r.e, 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. sh.o.r.es, and encompa.s.sing 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 cla.s.s. 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 (lat.i.tude 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 s.p.a.ce 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 acc.u.mulation 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 sh.e.l.ls, but others did not; and these closely resembled a formation at King George's Sound, princ.i.p.ally 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 cla.s.s 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 sh.o.r.es; 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 sh.o.r.es of SAPY Bay. From the same authority it appears (page 610) that reefs fringe the island of TIMOR-YOUNG, on the N. sh.o.r.e of Sumbawa; and, likewise (page 600), that BALLY town in LOMBOCK, is fronted by a reef, stretching along the sh.o.r.e 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 sh.o.r.es 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.

JAVA.

My information regarding the reefs of this great island is derived from the chart just mentioned. The greater part of MADUARA is represented in it as regularly fringed, and likewise portions of the coast of Java immediately south of it. Dr. Horsfield informs me that coral is very abundant near SOURABAYA. The islets and parts of the N. coast of Java, west of POINT BUANG, or j.a.pARA, are fringed by reefs, said to be of coral. LUBECK, or BAVIAN Islands, lying at some distance from the sh.o.r.e 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 sh.o.r.es 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 sh.o.r.e, 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.

MACa.s.sAR STRAIT.

The EAST COAST OF Borneo appears, in most parts, free from reefs, and where they occur, as on the east coast of PAMAROONG, the sea is very shallow; hence no part is coloured. In MACa.s.sAR Strait itself, in about lat.i.tude 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 lat.i.tude 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 s.p.a.ce 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-cla.s.ses, 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 sh.o.r.e, with deep water within; and in the ”Voyage of the 'Coquille',” some neighbouring islands are represented with reefs a good way distant, but I do not know whether with deep water within. I have not thought the evidence sufficient to permit me to colour them.

SUMATRA.

Commencing with the west coast and outlying islands, ENGANO Island is represented in the published chart as surrounded by a narrow reef, and Napier, in his ”Sailing Directions,” speaks of the reef being of coral (also Horsburgh, volume ii., page 115); coloured red.--RAT Island (3 deg 51' S.) is surrounded by reefs of coral, partly dry at low water, (Horsburgh, volume ii., page 96).--TRIESTE Island (4 deg 2' S.). The sh.o.r.e 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 (lat.i.tude 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 ma.s.s of sand and coral.--PULO PISANG; Horsburgh (volume ii., page 86) says that the rocky coral-bank, which stretches about forty yards from the sh.o.r.e, 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 BRa.s.sA (5 deg 46' N.). A reef surrounds it at a cable's length (Horsburgh, volume ii., page 60). I have coloured all the above-specified points red. I may here add, that both Horsburgh and Mr.

Moor (in the ”Notices” just alluded to) frequently speak of the numerous reefs and banks of coral on the west coast of Sumatra; but these nowhere have the structure of a barrier-reef, and Marsden (”History of Sumatra”) states, that where the coast is flat, the fringing-reefs extend furthest from it. The northern and southern points, and the greater part of the east coast, are low, and faced with mud banks, and therefore without coral.

NICOBAR ISLANDS.

The chart represents the islands of this group as fringed by reefs. With regard to GREAT NICOBAR, Captain Moresby informs me, that it is fringed by reefs of coral, extending between two and three hundred yards from the sh.o.r.e. The NORTHERN NICOBARS appear so regularly fringed in the published charts, that I have no doubt the reefs are of coral. This group, therefore, is coloured red.

ANDAMAN ISLANDS.

From an examination of the MS. chart, on a large scale, of this island, by Captain Arch. Blair, in the Admiralty, several portions of the coast appear fringed; and as Horsburgh speaks of coral-reefs being numerous in the vicinity of these islands, I should have coloured them red, had not some expressions in a paper in the ”Asiatic Researches” (volume iv., page 402) led me to doubt the existence of reefs; uncoloured.

The coast of MALACCA, TENa.s.sERIM 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 sh.o.r.e 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 Ba.s.sELAN, 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 sh.o.r.e, but the water is exceedingly shallow; uncoloured. The western sh.o.r.e of Palawan will be treated of under the head of China Sea.

PHILIPPINE ARCHIPELAGO.

A chart on a large scale of APPOO SHOAL, which lies near the S.E. coast of Mindoro, has been executed by Captain D. Ross: it appears atoll-formed, but with rather an irregular outline; its diameter is about ten miles; there are two well-defined pa.s.sages 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.

c.u.ming, who has lately investigated with so much success the Natural History of the Philippines, informs me, that about three miles of the sh.o.r.e 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. c.u.ming visited some fringing- reefs on parts of this coast, namely, near Puebla, Iba, and Mansinglor. In the neighbourhood of Solon-solon Bay, the sh.o.r.e 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. c.u.ming, 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 princ.i.p.al fringing-reefs on the coasts of Luzon; and they have all been coloured red.

Mr. c.u.ming 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 sh.o.r.e. Within the Philippine Archipelago, the sh.o.r.es of the islands do not appear to be commonly fringed, with the exception of the S. sh.o.r.e of MASBATE, and nearly the whole of BOHOL; which are both coloured red. On the S. sh.o.r.e 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 cla.s.s. With respect to the eastern coasts of the whole Archipelago, I have not been able to obtain any account.

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