STRUCTURE OF CORAL ISLANDS. 163 



Lagoon narrow, without entrance. Width of island from sea 

 to lagoon, one hundred to four hundred yards : width greatest 

 at south end. Beach ten feet high. The soil of the island 

 consisted of coral fragments and sand. Shore platform fifty to 

 eighty feet wide ; five or six feet of water over it at high tide. 

 Cut up very irregularly by channels three to eight or ten feet 

 wide. Observed small corals growing on the bottom outside 

 of the platform. Shores of lagoon shallow for fifty yards, and 

 consisting of coral sand. Beyond this a slope covered with 

 growing corals ; the corals rather tender species of Madrepores. 

 In the interior of the lagoon many knolls and large patches 

 of coral. 



Duke of York's.— %^ 38^ S., 172° 27' W. Form irregularly 

 oblong, trending north-west. Length, 3I miles ; breadth, 2 

 miles. Circuit, 9J miles, and about one-half wooded in 

 patches. South-west reef mostly bare. A lagoon, but without 

 entrance except for canoes at high tide, on leeward side. 

 Island ten feet high. Shore platform narrow, and intersected 

 by channels. Shores lined by reef-rock, two or three feet out 

 of water, indicating an elevation of the island. This reef-rock 

 consists of various corals firmly cemented. Within the lagoon, 

 knolls of coral, but none near the shore on the leeward side. 



Fakaafo or Bowditch's. — 9° 20' S., 171° 5' W. 6| miles by 

 4. Shape nearly triangular. Circuit seventeen miles, about six 

 of which are wooded in several patches, separated by long 

 bare intervals. A large lagoon, but no ship entrance. Height 

 of island, fifteen feet. Width to the lagoon, one hundred to 

 two hundred yards. Soil of the island coral sand, speckled 

 black with results of vegetable decomposition. Shore platform 

 narrow. At outer edge a depth of three fathoms, and from 

 thence gradually deepens, and abounds in corals for fifty yards, 

 when it deepens abruptly. Coral reef-rock elevated three or 

 four feet, indicating an elevation of the island. Lagoon 

 shallow, with some growing coral, but none near the shore. 

 Some corals growing on the platform, near its margin, mostly 

 small Madrepores, Astraeas, Nullipores. Fragments of pumice 

 were found among the natives, which had floated to the island 



M 2 



