388 J. STANLEY GARDINER. 



as well as by sandstone in the beach to the S. To the N. there has been much washing away 

 in the past, but along the W. half of this shore there is now some piling up of coral masses, 

 etc., these in one place overlying a line of beach sandstone. The E. end has no definite reef, 

 sloping graduallj' to 17 fathoms, with a sandy bottom on which a few coral colonies here and 

 tliere manage to live. The presence at this end of the island of an upper sand cliif of 2 feet, 

 separated by a terrace 60 yards broad from a lower fall of 4 feet, possibly indicates a washing 

 away. The terrace, however, does not seem to ha^e ever been covered with vegetation, and was 

 formed, I am inclined to consider, by a piling up of the sand in recent times. 



Mudduwari has large beach sandstone masses E. and W. and a rocky island covered with 

 trees to the S., evidently a very few years ago— the natives say 30 years — joined to the main 

 island. Round the whole reef are a series of masses of the raiseil rock, showing that the original 

 island was nearly conterminous with its reef. The large island is built up entirely of sand, but 

 this a few feet below the surface is so coarse and sharp-angled that it would scarcely seem to 

 have been washed up by the sea. (See also p. 165.) 



Fusmundu besides its velu is remarkable for the wasliing away of the shore and the 

 formations of sandstone to the S. and S.W. The islet is composed entirely of sand, and both 

 land and reef appear to be growing out to the east, the reef in addition having a point to the 

 west. The reefs N.W. to Kutai all seem to be to some extent growing out in the direction 

 of the current; most have some sort of a velu. On the larger are found at their seaward ends 

 between tide marks broad boulder zones of recent formation, almost " stony patches." 



IV. MiLADUMADULU (PI. XX.). 



This bank is arbitrarily divided for governmental purposes into two parts, to which are 

 given different names, Tiladumati and Miladumadulu, but between which there is no geogi-aphical 

 separation. The whole bank differs from all other Maldivan ones in its islands being so widely 

 separated from one another that in all, or nearly all, parts almost oceanic conditions prevail. 

 Yet, owing to the water passing for some distance over a bottom of decreased depth, there has 

 been developed a certain amount of difference between the seaward sides of the rim reefs 

 and those which face towards, or rise upon, the centre of the bank. Against the sea heavy 

 breakers are found, while within even the most open part of the bank they are never of 

 any importance. Such breakers would imply strong under-currents outwards along the slope 

 of the reef (see p. 24), while owing to the shallow depths on the bank the currents simply 

 diverge on either side of any reef The plankton crossing the surface would be plentiful 

 enough, but might not be suitably distributed by the currents over the bank. Again, the 

 water outside would be clearer and more charged with carbonic acid gas, the main food of 

 reef corals and nullipores, while, after crossing any part, it would be bound to have picked 

 up some amount of dirt, and much of its carbonic acid gas would certainly have been used 

 up and not replaced. The extremes of temperature are more widely separated upon the bank, 

 but, the average being about the same, it is difficult to see that this circumstance could have 

 much . effect on the growth of the organisms. 



Nevertheless, the openness of the rim of Miladumadulu must be of some considerable 



importance, since it was only' on this bank that we found the existence of a definite reef 



flat off any of the central islands, together with a well-formed fissure zone and gi-adual slope 



outside to the general level {vide Dureadu below). Alone in the interior of this bank also 



' N. Mahlos is to some degree an exception (see Chapter vi.). 



