340 AUSTEAIASIA. 



emerging", some still covered by water. In its middle and northern sections 

 Chambeyron's "great barrier reef " everywhere presents a uniform mass from 200 

 to 1,000 yards broad, interrupted only by a few passes, which give access to a 

 broad and deep sheet of smooth water flowing between the reef and the mainland. 

 This basin is about 6 miles wide and from 25 to 30 fathoms deep towards the 

 centre ; but the navigation is endangered by a few hidden shoals occurring near 

 both margins. 



Seawards the great reef sinks rapidly, and then at a mean distance of 450 

 yards plunges abruptly into depths of over 350 fathoms. Nowhere else does 

 Darwin's hypothesis regarding the slow subsidence of fringing coralline reefs 

 appear to be better supported than in these waters. The coral builders work with 

 surprising rapidity on the New Caledonian reefs. North of the mainland the 

 two branches of the fringing barrier do not converge, but, on the contrary, grow 

 wide apart and stretch for a distance of 160 miles before they become reunited 

 north of the Huon, Fabre, Leleizour, and Surprise islets. Between this perfect 

 atoll and the north end of the great island, the lagoon, enclosed by the two barrier 

 1 eef s, is occupied in its central part by the Belep group, which comprises the islets 

 of Art and Pott. 



The Loyalty chain, built up by polypi, presents in a summary form the whole 

 history of coralline islands. The Pétrie and Astrolabe reefs in the north are 

 dangerous shoals, awash with the surface and grouped as atolls. Uvea, following 

 southwards, is a semi-circular coral plateau, perfectly horizontal, with a mean 

 height of 50 to 60 feet, and enclosing a lagoon 9 fathoms deep. Lifu, largest 

 member of the archipelago, is also an ancient atoll, which has been upraised at 

 successive epochs to an altitude of 300 feet. The observer easily distinguishes 

 the three terraces marking three consecutive upheavals, and disposed in abrupt 

 scarps like the outer cliff at present washed by the waves. Mare, or Nengonë, 

 some 30 feet higher than Lifu, develops five horizontal terraces, which indicate a 

 corresponding number of changes between the level of land and sea. Having risen 

 above the surface at a more remote period than the other islands, Mare is also 

 more fertile, better wooded, and relatively more densely peopled. To judge from 

 the numerovis shells of still surviving species which occur on the upper terraces 

 and which partly retain their colours, the last upward movement must have taken 

 place in recent geological times. 



With a mean annual rainfall of about 40 inches, New Caledonia is abundantly 

 watered by numerous streams, one only of which is sufficiently copious to deserve 

 the name of river. This is the Diahot, which rises at the foot of the Panic Peak 

 and flows parallel with the east coast to Harcourt Bay, between the two north- 

 western promontories of the island. Including its windings the Diahot is over 60 

 miles long, and in its tidal reaches is accessible to craft drawing 8 or 10 feet of 

 water. The Toutouta, which falls into Saint Vincent Bay, north-west of Noumea, 

 as well as several other rivulets, flows for a large part of its course below the sur - 

 face, and near its source in Mount Humboldt develops a copious cascade at a 

 height of 4,000 feet above the sea. Judging from their high temperature some 



