FRYER— FORMATION OF ALDABRA, ETC. 



431 



VIII. ASSUMPTION. (Plates 28 and 29.) 



Assumption Island is situated in lat. 9° 46' 20" S. and long. 46° 30' 30" E., and unlike 

 the islands previously noted is not an atoll. It is crescent-shaped, about 3| miles long, 

 and varies from 1 mile to about a third of a mile in width. In composition it is 

 undoubtedly an elevated reef, corals in position of growth being abundantly seen, 

 especially along the cliffs of the east coast and on the sides of large pits in the rock, 

 which are extremely common. Much metamorphosis has occurred in places in the 

 interior of the island, and as usual phosphatic inclusions are always present, and give 



(J* fJand Dune no** aMoUC 



""<■ 



y 



40 



Fig. 3. Assumption Island. 



evidence of the quantity of guano which was deposited on it. There is still a fair quantity 

 of this substance in hollows in the rock and also along the east coast, where it forms 

 a covering over the rock about 6 inches deep. 



A conglomerate somewhat resembling the Aldabra "platin" is generally distributed, 

 but from the nature of the component corals it appears probable that this limestone 

 is the result of great denudation acting on a rock composed of corals in position of 

 growth : it is in the nature of a superficial layer and does not extend downwards for 

 many feet. Underneath it the corals in the rock are almost all in the position 

 of growth. 



Variations in level over the island were, owing to a thick bush, difficult to estimate, 

 but judging from three tracks cut from the east coast to the west coast, there is a slight 



55—2 



