GEOLOGY. 193 



blocks dissected out from it. Huge boulders of similar origin are 

 met with on the shore, and in deep artificial excavations such as 

 monitor cuts. In many cases it is unnecessary to suppose their 

 transport by cataclysmic floods to explain their presence— they 

 have merely settled down as weathered, interstitial stuff has been 

 removed from between them, helped no doubt by surface creep 

 and by landslips. 



On headlands along the coast there is a space of bare curving 

 surfaces of rock, perhaps twenty or thirty feet in vertical height, 

 between high water level of spring tides and the beginning of the 

 forest. There the soil and soft rock are washed away by occasional 

 monsoon gales but marine action is neither continuous enough nor 

 violent enough to produce its characteristic erosion effects. This 

 glacis shows a certain amount of platy jointing, thick slabs splitting 

 off parallel to the surface, but to a much less extent than is seen 

 in dry tropic climates with great temperature ranges. In an equable 

 climate like that of Tavoy changes of temperature must have com- 

 paratively little effect; probably this is merely a laying bare by 

 the waves of what has taken place below a recently removed soil- 

 cap, and it is the circulating subsoil water charged with carbonic 

 and humic acids and the seasonal changes of waterlogging and 

 drying which produce weathering in zones roughly parallel to the 

 ground surface. Between tide levels on head-lands there exists 

 a jumbled scree of angular and subangular boulders produced by 

 the rougher mechanical action of the waves, while in sheltered 

 places between high and low water is a sloping platform of quaintly 

 scalloped rock, fretted out by the solvent action of the water and 

 by its mechanical action in its gentler phases. In the latter situa- 

 tion an occasional variety of jointing is that in which the granite 

 breaks up into ovoids with concentric exfoliating layers an inch 

 or two thick. This is prebably an effect of original cooling taking 

 place from numerous different centres in the magma. The condi- 

 tion is never seen under ordinary subaerial weathering, nor where 

 water action is strong, probably because it is masked by ordinary 

 weathering and denudation and requires special conditions to make 

 it apparent. 



Inclusions of Mergui rocks of all shapes and sizes are very common 



in the granite, especially of course near the 



Xenohths. peripheries of intrusions, but they also occur 



more sparingly in deep seated portions, such as in the section* 



C2 



