62 VOYAGE TO THE 



and has a flat surface nearly eighty feet above the sea. 

 On all sides, except the north, it is bounded by per- 

 pendicular cliffs about fifty feet high, composed en- 

 tirely of dead coral, more or less porous, honeycomb- 

 ed at the surface, and hardening into a compact cal- 

 careous substance within, possessing the fracture of 

 secondary limestone, and has a species of millepore 

 interspersed through it. These cliffs are consider- 

 ably undermined by the action of the waves, and 

 some of them appear on the eve of precipitating 

 their superincumbent weight into the sea ; those 

 which are less injured in this way present no alter- 

 nate ridges or indication of the different levels which 

 the sea might have occupied at different periods, 

 but a smooth surface, as if the island, which there is 

 every probability has been raised by volcanic agency, 

 had been forced up by one great subterraneous con- 

 vulsion. The dead coral, of which the higher part 

 of the island consists, is nearly circumscribed by 

 ledges of living coral, which project beyond each 

 other at different depths ; on the northern side of 

 the island the first of these had an easy slope from 

 the beach to a distance of about fifty yards, when 

 it terminated abruptly about three fathoms under 

 water. The next ledge had a greater descent, and 

 extended to two hundred yards from the beach, 

 with twenty-five fathoms water over it, and there 

 ended as abruptly as the former, a short distance 

 beyond which no bottom could be gained with 200 

 fathoms of line. Numerous echini live upon these 

 ledges, and a variety of richly coloured fish play 

 over their surface, while some cray-fish inhabit the 

 deeper sinuosities. The sea rolls in successive break- 

 ers over these ledges of coral, and renders landing 



