GEOLOGICAL OHSEUVATIOXS I\ FMI. 



03 



agglomerates a platform 100 to 300 feet wide, at the present sea-level. 

 The width of the bench indicates a crustal stability of some duration. 

 Yanuia, Mana, and other limestone islands about the border of the 

 lagoon are largely composed of reef material in place. Coral heads 

 often form 50 per cent of the ^'isible limestone. The elevated limestone 

 with its surface now 15 to 20 feet above sea, has been greatly etched 

 by solution, with the generation of thousands of sharp points which 

 make the surface nearly impassable. The dips of the limestone as 

 taken on the ]\Iana Islands were 18° and 11° S. and on the Yanuia 

 Islands 15° S. E. Since there is no evidence of tilting in the group, 

 these dips apparently represent original angles of deposition. 







Figure 30. View of Ndui from One Levu. 



The recurrence of the limestone islets at intervals about the edge of 

 the reef seems best explained on the assumption that they are rem- 

 nants of a more or less continuous mass of limestone, which has been 

 largely destroyed and on which the present barrier reef has developed. 

 Though no solid limestone is exposed in Ndui (Figure 30), the close 

 proximity of limestone islets suggests the presence of a limestone 

 basement beneath the sand. The prevailing easterly winds sweep the 

 sand from the eastern side of the lagoon arovmd the A'olcanic islands, 

 and pile it against the western reef at its inner border, in the lee of the 

 volcanic islands. Practically no coral grows in the lagoon near its 

 western side. Sand flats, fordable at low tide, extend from the island 

 out to the reef. 



