292 Christmas Island. 



would perhaps be more fitly called talus slopes, since it is i-are 

 or an actual cliff face to be seen, tbc usual form being a steep 

 (30°-40°) slope strewn with, jagged blocks of limestone sometimes 

 arranged more or less in a succession of small terraces. A general 

 account of them has been given on p. 11. The upper clitf 

 consists entirely of white and cream-coloured limestones, which 

 towards the summit are often more or less dolomitized, and 

 are nearly always more or less cavernous, owing partly to the 

 crystallization which has usually taken place to a greater or less 

 extent. Traces of coral are rare, but in one or two cases I found 

 a rock apparently made up of broken pieces of a brancliing coral. 

 Some of the beds consist largely of foraminifera, fragments of 

 moUusca, and other organisms. At 725 feet over West White 

 Beach I found a bed composed almost exclusively of a small lamelli- 

 branch, but this was on the south-west side of Murray Hill and 

 perhaps belongs rather to the plateau than the upper cliff. Many 

 of the rocks are clearly of fragmental origin, and consist of angular 

 fragments of older limestones in a later calcareous matrix. No 

 Orbitoides were seen. The rocks on the whole are such as might 

 have accumulated on the submarine slopes outside a living reef, 

 and, in fact, are probably largely composed of the debris derived 

 from the wear of the rocks described above as forming the rim of 

 the plateau. This upper slope is separated from the one below by 

 a level terrace of varying width, usually soil-clad, but occasionally 

 studded with blocks and pinnacles of limestone. 



The second inland cliff, like the upper one, is generally reduced 

 to a mere slope covered with talus, but in a few places, e.g. to 

 the north of Steep Point on the east coast, it forms a vertical face. 

 In it coral is found much more often than in the upper cliff, and 

 at the locality just referred to numerous masses of it can be seen 

 embedded in the limestone. Fragmental limestones are again 

 common, and pieces of echinoid spines and molluscan shells are 

 frequently met with ; in some cases foraminifera are very numerous. 

 The limestones are occasionally more or less dolomitic (see 131, 

 p. 257), and in a few cases are partly phosphatized (940, p. 261). 

 In this last case the limestone in question occurs below Phosphate 

 Hill, and the contained phosphate was no doubt derived from that 

 covering the slopes above. No. 131 is from a narrow valley on 

 the summit of the first inland cliff, between its outer edge and 

 the foot of the second inland cliff. 



First Inlak^d Cliff. 



The general characters of this cliff have been described above 

 on p. 10 : both in its mode of origin and composition it is much 

 more complex than the slopes above. It may consist either of 

 (1) limestones of the central nucleus, containing Orbitoides, as at 

 North-East Point, or (2) limestones of later date, largely made up 

 of corals, molluscan shells, echinoid fragments, foraminifera, and 



