546 



NATURE 



{April ^, 1888 



further excursion to the south-east to a savanna region, situated 

 in a depression among the mountains, and called by the natives 

 " Valle Nuevo." The path led over forest clad mountains with 

 intervening gorges, and formed a continual ascent till the Valle 

 Nuevo was reached, which is 7450 feet above the sea. One of 

 the forest tracts which the traveller traversed was especially 

 dense and almost impassable ; beautiful mosses, ferns, orchids, 

 lycopods, and other epiphytes were growing on the trees. The 

 Valle Nuevo is surrounded by low hills, which form the culmi- 

 nating points of the range ; the highest of these, viz. Pico del 

 Valle Nuevo (8630 feet above the sea-level) was ascended by the 

 traveller. 



Dr. Rink contributes to the current number of Pttennann's 

 Mitteilungen an accjunt of the results of the recent journeys 

 made by Lieuts. Ryder and Block along the coast of Green- 

 land to the north of Upernivik in 1887. By accurate measure- 

 ments made in the ice- fiords of Angpadlar Fok, &c., both in 

 April and August, some interesting and important results have 

 been secured as regards the physical geography of this region. 

 Some of the ice-fiords are very prolific in ice-bergs, notably 

 that of Giesecke, where the edge of the permanent ice has 

 retreated considerably within recent years. The results show 

 not only the extraordinary rapidity, but the great variableness in 

 the movements of the ice, apart apparently from the temperature 

 of the time of year. The average temperature of the air during 

 the measurements from April 20 to 24, was from - 9° F. to - 15°. 

 On January 28 the water temperature, at a point where the ice- 

 fiord was 512 fathoms in depth, was as follows : at the surface 

 27°7 F., at 50 fathoms 28°'9, at 200 fathoms 32°, and at 287 

 fathoms 32°*2. The question of the limit and movements of the 

 inland ice of Greenland, to which the attention of recent Danish 

 explorations has been directe-i, and towards the solution of which 

 the results obtained by Lieuts. Ryder and Block have materially 

 contributed, is discussed by Herr Rink in his paper, which also 

 gives some interesting notes on the botany, geology, and 

 ethnography of the country. 



In the April number of the Proceedings of the Royal 

 Geographical Society there is an excellent new map of Siam, 

 based on the surveys of Mr. James McCarthy. There also 

 will be found the second and third of General Strachey's 

 Cambridge geographical lectures. 



At the last meeting of the Royal Geographical Society a 

 paper of unusual interest and originality, on the Solomon Islands, 

 was read by Mr. C. M. Woodford, who spent several months in 

 the group in 1886-87. M"". Woodford's attention was mainly 

 directed to Treasury Island, his head-quarters for some months 

 being at Alu, on that island. He made many journeys into the 

 interior, and was so successful that he obtained nearly 17,000 

 specimens in natural history, which, so far as they have been 

 examined, have been found to coaiprise three ne.v genera, a.nd 

 eight new species of mammals, fifteen new species of birds, six 

 new species of reptiles, and over a hundred new species of 

 Lepidoptera. Mr. Woodford visited, besides Treasury Island, the 

 islands of Fauro, New Georgia, Guadalcanar, and others, explor- 

 ing their interiors as far as possible, and in the case of Guadal- 

 canar attempting to ascend Mount Lamna. (8000 feet), without, 

 however, succeeding. He followed the Bokokembo River as far 

 as possible, finding the vegetation most luxuriant, and composed 

 of large Ficus and other forest trees, with occasional clumps of 

 sago and areca palms, but few coco-nuts. The coast natives are 

 greatly afraid to venture into the interior, partly through feir of 

 the bush-folk who live in the mDuntains, and partly through 

 superstition. Mr. Woodford's observations on the natives are 

 of great value ; he had unusual opportunities of observing their 

 modes of life. They are mostly inveterate head-hunters and 

 cannibals. Natives of different parts of the group dift'er con- 

 siderably from one another, but they belong to the Melanesian 

 or Papuan type. Mr. Woodford believes, however, that on the 

 island of Ysabel there is a strong infusion of Polynesian blood 

 from Ongtong Java, or Lord Howe's Group, as canoes are 

 known to have been driven in bad weather from that group, 

 and to have arrived on the coast of Ysabel. The natives of 

 Bouka and Bougainville, and of the islands of Bougainville 

 Straits and of Choiseul, are intensely black in colour, but as one 

 journeys eastward the colour changes to a dark brown. They 

 have woolly hair, but occasionally natives are met with wavy, 

 and in some cases straight hair. Mr. Woodford attributes this 

 fact to an infusion of Polynesian blood, and has noticed it in 

 natives from Ysabel, also at Fauro. 



The Royal Geographical Society of Sweden has awarded the 

 Vega Gold Medal — instituted in honour of Nordenskiold's voyage 

 — to Dr. Wilhelm Junker, the celebrated African traveller. The 

 medal, which has not been awarded since 1884, has hitherto had 

 only four recipients, viz. Nordenskiold, Palander, Prejevalsky, 

 and Stanley. 



THE A TOLL OF DIEGO GARCIA AND THE 

 CORAL FORMATIONS OF THE INDIAN 

 OCEAN.^ 



T^IEGO GARCIA is a typical atoll ; a narrow strip of land 

 varying in width from a mile to 30 yards, nearly completely 

 encircles a lagoon of irregular shape. The lagoon is open to the 

 ocean towards the north-west, its mouth being divided by three 

 small islets into four channels, of which three are sufficiently deep 

 to allow ships to enter the lagoon. The whole of the land compos- 

 ing the atoll is very low ; the highest point in the island is not 

 more than 30 feet above the level of high tide, and this height, 

 which is quite exceptional, is due to the accumulation of great 

 heaps of sand through the action of the south-east trade winds 

 which blow with considerable strength for more than one-half of 

 the year. Diego Garcia is the southernmost atoll of the Chagos 

 Group ; it lies in S. lat. 7° 26', E. long. 72° 23', and forms the 

 last of the 'great chain of coral formations reaching from the 

 Laccadive Islands, through the Maldives to the Chagos Group. 

 To is south-west lie the subTicrged atoll-shaped reefs known as 

 Pitt's Bank and Centurion's Bank, to its north lies the huge sub- 

 merged atoll known as the Great Chagos Bank. It is an inter- 

 esting fact that throughout the Laccadive, Maldive, and Chagos 

 Groups there is no instance of a fringing or of a barrier reef ; 

 nothing but coral structure rises above the waves ; all the islands 

 are atolls ; none of these are upraised, but there are several sub- 

 merged banks. The existence of this long line of atolls seemed 

 to be one of the strongest arguments in favour of Darwin's theory 

 of the formation of coral reefs. 



In Diego Garcia the nature of the soil varies considerably from 

 place to place. In some localities it consists of nothing else than 

 bare coral rock upon the surface of which coral boulders are 

 scattered about ; in other places it is composed wholly of calcare- 

 ous sand, and one may dig down for 6 or 8 feet without finding 

 coral rock. It is obvious after a short examination ,that some 

 parts of the land are older than others, and that the great strip of 

 land was formerly a series of disconnected islets which have since 

 been joined together by the accumulation of sand and coral 

 debris between them. In the older parts of the island, which 

 have apparently been covered with vegetation for a considerable 

 period, a thick peaty mould has been formed by the decay of 

 fallen leaves and stems of trees and shrubs. 



Throughout the island the outer or seaward shore is higher 

 than the inner or lagoonward shore, owing to the pile of coral 

 boulders thrown up in the form of a low rampart along the 

 former by the action of the waves. In most places a flat reef 

 extends fully 60 yards seaward of the rampart ; and this reef is 

 just uncovered at low spring tides. As a rule the inner shore 

 slopes gently down into the lagoon fc«- some distance, and then 

 pitches down rather suddenly to a depth of lo or 12 fathoms, 

 but in some places there is a depth of 6 or 8 fathoms close up to 

 the inner shores. Marshy pools of fresh or brackish water are 

 found in the centre of the strip of land on the south-east and 

 west sides of the island ; into these the sea enters in many cases 

 daring the highest spring tides, and at the south-east and south 

 ends of the island it has established permanent breaches into some 

 of these pools, through which the tide runs in and out regularly 

 from the lagoon. Thus there are formed sheets of water like 

 secondary lagoons within the strip of land ; these are known on 

 the island by the name of barachois, and they are of some im- 

 portance when one comes to consider the amount of change 

 which is continually going on in the island. 



Externally the shores slope away very rapidly to considerable 

 depths, the sounding-line giving depths of 250 fathoms and 

 upwards at a distance of a few hundred yards from the edge of 

 the reef, excepting^ at Horsburgh Point at the south-east side, 

 where a depth of 45 fathoms is found at a distance of i mile from 

 the shore. After a stay of two or three months on the island 

 one cannot fail to be impressed with the immense amount of 



' By G. C. Bourne, B A., F.L S., Fellow of New College and Assistant 

 to the Linacre Professor in the Un varsity of Oxford. Communicated to the 

 Royal Society by Prof. E. Ray Lankester, F.R.S. 



