294 Christmas Island. 



this a still later one at about 100 feet. Again, between Flying Fish- 

 Cove and North-East Point, for the greater part of the distance 

 the single high cliff which is found at the Zigzag (see Fig. 6) is 

 replaced by two or three irregular step-like cliffs of reef-limestone, 

 often interrupted by talus slopes, gaps, and channels, and in fact 

 representing the remains of a series of fringing reefs, each of 

 which in turn was raised and cut back by the sea, while at its foot 

 its successor grew up on the talus derived from the cliffs above. 

 Whether a single vertical cliff face or a succession of terraces was 

 formed depended upon the steepness of the submarine slopes. 

 If these were gentle enough to allow talus material to accumulate 

 and afford a foundation for a fringing reef the terraced condition 

 followed, but if on the other hand the slopes were steep and 

 no reef could grow, a vertical cliff was formed. It should be 

 noted that all intermediate conditions occur, the commonest being 

 that in which the upper 150 feet or so form a vertical face, while 

 the foot, from the shore terrace up to about 100 feet above the sea, 

 is formed by a narrow belt of reef. This corresponds to the terrace- 

 between the 100 feet and 180 feet contour-lines in Fig. 6, and 

 is the most persistent of these minor terraces. In some places 

 shore conglomerate was observed on its surface, and great limestone 

 blocks fallen upon it from the cliffs above rest on a sort of pedestal 

 of cemented coral fragments like .that which is found at the base of 

 the blocks lying on the present fringing reef. Of course these 

 raised fringing reefs are of later date than the rocks in which the 

 first inland cliff has been carved by the sea, and the lower ones 

 may be but little older than the reef forming the present sea cliff 

 and terrace. This probably accounts for the fact that some of the 

 corals labelled as from the first inland cliff are similar to those 

 found in the sea cliff and to recent forms. 



The Shoee Cliff aijd Terrace. 



The shore terrace and cliff (see pp. 6-10) are formed by the 

 elevated fringing reef that grew round the island before the last 

 negative movement of the shore-line took place. It is the most 

 persistent of the terraces, and, with the exception of about a quarter 

 of a mile in two localities, it runs round the whole island. In 

 some places, as above mentioned, it may be in part formed by the 

 volcanic and other rocks of the central nucleus, but elsewhere it 

 may be described as consisting of a thin capping of coral limestone, 

 resting on a foundation of consolidated talus derived from what are 

 now the inland cliffs, and, of course, varying in characters as the 

 rocks composing those cliffs vary. For instance, on the east coast, 

 in the neighbourhood of the fresh-water stream both the talus- 

 foundations and the reef - limestone overlying it are full of block* 

 of basalt derived from the exposure on the slopes behind. 



The shore cliff forming the southern boundary of Flying Fish 

 Cove may be taken as fairly typical of the shore cliff in general. It 



