OTHER CORAL STRUCTURES 283 



outcome of subaqueous processes, and it is impossible to con- 

 ceive a breccia platform to be made in situ beyond tbe reach 

 of the waves ; indeed when the composite rock is long exposed 

 to the air, and rain water, it suffers a certain amount of 

 disintegration, and its sub-aerial life is a limited one. Since 

 breccia platforms may to-day be found intact, and exactly in the 

 condition in which they were laid down, beyond the reach of 

 the highest spring tides, it is evident that since the date of 

 their formation they have been elevated by an actual upward 

 movement of the land. Between Pulu Tikus and Pulu Pasir 

 these signs of elevation are striking. A notable fact in their 

 disposition is that they occur in series, one layer above the other ; 

 successive land movements being registered by successive steps 

 of breccia, which rise one above the other to a total number 

 of three or four, and to a height of almost as many feet. 

 At that part of Pulu Tikus where these steps are evident, 

 the island rise is thirteen feet above mean tide-level, and is 

 by far the highest land of the island. I can imagine no other 

 explanation for the presence of these raised platforms than 

 that afforded by the supposition that the land on which they 

 were laid down has been raised, as a whole, since their forma- 

 tion, and on the evidence of these raised platforms I presume 

 the Cocos-Keeling atoll to have been subjected, locally, to 

 successive slight waves of elevation. 



The positive evidence afforded by raised seaward beaches 

 is not so strong, for gales of abnormal violence may alter the 

 configuration of the debris bank so markedly that a raised 

 field of broken coral may be the work of a few short hours of 

 storm, and the loose fragments may be easily thrown beyond 

 the reach of any subsequent high spring tide. The formation 

 of breccia platforms must of necessity be very slow, and no 

 sudden violence or temporary condition can cause the building 

 of breccia beyond the normal reach of the waves. Wherever, 

 therefore, raised and intact platforms of breccia are found, 

 we may safely argue that actual elevation of land- level has 

 been brought into play ; but when raised debris beaches or 

 raised sand beaches are found, then although every appearance 



