GEOLOGICAL OUSP:UVATIONS IN FIJI. 



51 



strait, a series of low, late-maturely eroded hills of pyritized tuffs are 

 overlain unconforinably by 150 to 200 feet of coralliferous liinestone. 



Susui. The western end of Susui, east of Malatta, is composed of 

 limestone. The two islands are separated by a tortuous passage, 

 only a hundred yards wide, through which runs a violent tidal current. 

 This portion of Susui is very rough, like Malatta. An inland lake 

 occurs near the passage, which is filled as the tide rises, and the fall 

 of the tide leaves the surface of the lake above sea-level. As a result, 

 the waters from the lake, draining off through underground channels, 

 rise in fountains off-shore within the intertidal zone. 



The limestones of Susui rest unconforinably on maturely eroded 

 andesite, composing the central portion of the island. The surfaces 



FiGXJKE 22. Sketch Map of Malatta and Susui, Exploring Group. 

 Black — elevated coral reef. White — volcanic rocks. Lined — sand 

 flats. 



of the andesitic hills bear silicified masses of coralliferous limestone 

 similar to those found on Vanua Mbalavu, suggesting that the lime- 

 stone once extended over these hills. 



A low sand flat, stretching entirely across the island, connects the an- 

 desite with a series of basaltic rocks which form the eastern end of the 

 island, (Figure 22). The basaltic formation is continued in a series 

 of agglomeratic islands extending in a curved line to the northeast. 

 Within the group of agglomeratic islands is one composed of limestone. 



