Christmas Island — Physical Features. 5 



The outlines of the land, as seen from the south-west, east, 

 and north, and sections across it at various points, are shown in 

 Pigure 1 and in the map. 



From these it can be gathered that the island consists of a 

 central plateau, highest towards the north and east, and descending 

 to the sea on all sides by a succession of terraces, separated by 

 slopes or cliffs. In most places the arrangement of these, from the 

 edge of the plateau downwards, is — (1) a steep slope strewn with 

 blocks ; (2) a broad terrace, followed by a similar slope (this 

 seems to be wanting on the south) ; (3) a second terrace, 

 terminating in a cliff 200 or 300 feet high; (4) the shore terrace, 

 sloping gently down to the sea cliff; (5) the present fringing reef. 

 There are, however, many local differences, the more important of 

 which will be noticed below. 



The greatest length of the island is from ^N'orth-East Point to 

 Egerici Point, a distance of about 1 2 miles. The greatest width is 

 from North-East Point to South Point (see Map), about nine 

 miles ; the least on a line drawn north and south through Murray 

 Hill, about three and a half miles. The total area of the island 

 may be roughly stated as 43 square miles. 



In giving a general account of the physical features of the island, 

 it will be convenient to begin with the fringing reef, and then deal 

 successively with the higher terraces, concluding with the plateau. 

 There are, besides, one or two localities which will need a somc- 

 Avhat more detailed description. 



The Fringing Reef. (Fig. 2.) 



If the coast be examined in a boat, or from the edge of the sea 

 cliff, it is found that round the greater part of the island there is 

 a submarine terrace or shelf, which varies greatly in width and in 

 its depth beneath the surface. At Flying Fish Cove this terrace 

 consists of two portions — an inner, which is partly dry at low- 

 water, and outside this and about two fathoms below it, a second, 

 which slopes away seaward to about 20-30 fathoms, beyond which 

 the water deepens suddenly. The upper reef is best developed at 

 the northern and southern ends of the cove, and is almost absent in 

 the middle. It exactly resembles the reef flat of an atoll. At 

 low-water it can be seen to be composed of blocks of coral cemented 

 together and forming a smooth, hard surface, like concrete, bored 

 in all directions by marine worms. Some of the individual coral 

 masses are of considerable size, and the section of one spherical 

 mass was about four feet in diameter. On the surface of the reef 

 are numerous loose blocks and large plate-like masses of coral, and 

 towards the beach are a number of enormous masses of white 

 foraminiferal limestone which have fallen from the high cliff above; 

 some of these are 20 feet high and 30 or more long, and several 

 have trees growing on tliem. In one case a block has rolled a dis- 

 tance of 50 or 60 yards out on to the reef flat. At the lowest tides 



