10 Christ mas Island. 



small brooks. These are never more than two or three hundred 

 yards long, and rise from springs, welling out at or near the base 

 of the inland cliif. Their banks are very muddy, and are burrowed 

 in all directions by a peculiar grey crab {Cardiosoma), which is 

 provided with a sort of brush on each side of the mouth, apparently 

 for filtering the water which enters the gill chamber. 



The First Inland Cliff and Terrace. (Fig. 5.) 



The first inland cliff is the most conspicuous feature in the 

 scenery, and in one form or another it extends round nearly the 

 whole island. In one place it forms a cliff with a nearly vertical face 

 bare of vegetation ; in another it is reduced to a talus slope of blocks 

 of limestone piled up in wild confusion and covered with trailing 

 plants and bushes ; and in others, again, it is replaced by a succession 

 of smaller cliffs and terraces of varying height and breadth, rising 

 step-like one behind the other. Whatever form it may take, its 

 summit is between 250 and 300 feet above the sea-level. On the 

 east coast, about half a mile south of North -East Point, this cliff is 

 absent for a short distance, and on the western coast it is much less 

 distinctly developed than elsewhere. In many places where the 

 cliff face is vertical, or nearly vertical, it shows distinct traces of 

 wave action at two or three levels, the chief evidence of this being 

 lines of small caves, and in places near the foot a very distinct 

 and clearly comparatively recent undercutting of the face. For 

 instance, on the north coast, at about 20 feet above the shore plat- 

 form, the cliff is cut back into a shelf, above which it overhangs 

 considerably, and from 150 to 200 feet higher up there are less 

 distinct traces of a similar structure, the line of wave action being 

 there marked by small caves. Where the single cliff face is replaced 

 by a number of secondary cliffs and terraces, these also indicate 

 that the surface of the sea has stood at successively lower levels 

 with regard to the land, each cliff and terrace apparently marking 

 such a change of level. In places these smaller cliffs and terraces 

 aie interrupted by gentler slopes, and one or more may disappear. 

 Although the terraces may be continuous for considerable dis- 

 tances, it is difficult to correlate those occurring in different parts 

 of the island. Both the mode of origin and the composition of 

 the first inland cliff seem to differ considerably in different places, 

 but these points will be more fully considered in the geological 

 section. 



The terrace on the top of the first inland cliff varies much in 

 width and general structure. It is widest opposite the principal 

 headlands, where it is between a quarter and half a mile wide ; 

 elsewhere it may be any width from less than 100 to 400 or 500 

 yards. It usually slopes gently seawards, sometimes becoming 

 steeper towards the cliff edge, which is nearly everywhere bordered 

 with a belt of pinnacles of coral limestone, separated by clefts and 

 channels often parallel to the cliff edge. In one or two places, 



