GEOLOGICAL OBSERVATIONS IN FIJI. 



93 



TABLE II. 



Dimensions of Reefs and Deepest Lagoon Soundings in the Lau Group. 



(The elevations of limestone masses within the reefs are given immediately 

 after names.) 



Wailangilala 

 DutY Reef 

 Williamson Reef 

 Dibble Reef 

 Naitamba (610') 

 Kimbombo 

 Bell Reef 

 Malima 



Exploring Group 

 Kanathea (350') 

 Mango (G30') 

 Malevuvu Reef 

 Vekai 



Katafanga (180') 

 Tuvuthd (800') 

 Thakau Tambu 

 Thakau Lasemarawa 



Reid Reef (60') 

 North Argo Reef (80') 

 South Argo Reef 

 Lakemba (320') 

 Aiwa (210') 

 Oneata (160') 

 Olarua 



Thakau ^'uite 

 Komo 

 Mothe 



Thakau Motu 

 Namukai Lau 

 Yangasa Group (390') 

 Thakau Levu 

 Fulanga (260') 

 Ongea (270') 

 Ono Group (15') 



Depth 

 fathoms 



21 

 26 

 36 

 14 

 23 

 20 



7 



16 

 17 



8 

 24 

 13 

 17 

 13 

 10 

 13 



6 



of the barrier reefs and atolls of the Lau islands. Fifty per cent of the 

 lagoons have maximum depths of between 60 and 90 feet. ^Yave- 

 erosion is ineffective at such depths within a lagoon. Solution by 

 ocean water is as inefficient a cause. Submergence is the only alter- 

 native, and, since the rise of the waters is more recent than the return 

 of the waters after the Glacial period, an actual subsidence must have 

 occurred. 



It is apparent that the movements have been very irregular. They 

 are confined to small segments of the earth's crust and are undoubtedly 

 associated with volcanic activity. In part the movements ha^^e been 

 due to the transfer of material from the inner to the outer portions 

 of the earth's crust; and in part to the secular condensation of the 

 extruded lavas and pyroclastics. (Cp. Gerland, 1895, p. 56, and Daly, 

 1915, p. 232). ■ 



Referring again to the theories of coral growth (p. 88), it is seen 

 that none of them, taken by itself, is applicable to the Lau islands. 

 None of the modern reefs appears to be growing on a submerged 



