MANGA REVA. 75 



Plate 86 shows a still lower stage of water on the reef flat, a great part 

 of which is dry, and the base of the coral rubble flat is flanked by large 

 horses of coral nibble still attached to the reef flat or piled together in 

 masses previous to being broken up and thrown upon the rubble flat. Plate 

 90, fig. 2, is a similar view to that of Plate 86. 



In Plate 83 the I'eef flat has not been ^^laned off to such an extent as 

 is seen in Plates 84-86, so that the coral rubble flat is low and has not 

 been thrown up into such high dams as in Plates 84, 86-88, where the 

 outer reef flat has been planed off to a very considerable extent. This is best 

 seen in Plates 84, 87, 88. The rubble dam is very high in Plate 87, where 

 the large coral shingle has encroached to a considerable extent upon the 

 vegetation growing on the ridge of the coral rubble beach dam. The extent 

 to which the rubble may encroach upon the vegetation is well seen in 

 Plate 88, which shows the inner slope of the coral rubble dam extending 

 towards the lagoon side. The whole of this slope is studded with patches of 

 vegetation which are gradually extending over it as fast as the coral shingle 

 becomes decomposed into coarse sand capable of supporting vegetation. 



