62 



rOYE. 



as the Mana islands. Elsewhere about the border, isolated toadstool 

 islets appear; on the western side of the lagoon in the lee of the largest 

 island (Ono Levu) a sand island, Ndui, has been built up. 



Ono Levu represents the southern third of the old crater wall. 

 It is crescentic in shape and at either end stand two flat-topped hills, 

 between which there is a low sag. The flows and agglomerates com- 

 posing the island dip outward from the central depression. They are 

 cut by a series of dikes which radiate from the old crater. 



The island has a low, rolling topography of late-mature hills of 

 deeply lateritized andesite. Erosion goes on rapidly during heavy 



Figure 29. Profiles of Ndoi, Ono-i-lau. 



a — Sand flat to leeward, b — Lateritized andesite flat at 100 feet, c 

 Hogbacks of andesitic flows, d — Central butte of agglomerate. 



rains; the water runs from the hills in sheets rather than in streams, 

 sweeping off layers of the lateritized soil. 



Ndoi shows outward dips and mature topograph}' like Ono Levu. 

 On its northern side a few hog-l)ack ridges are composed of relatively 

 resistant lava flows between the softer ash-beds. A well defined 

 wave-cut bench surrounds this island at an elevation of about 100 

 feet. Though present in the other island, the bench is there not so 

 well preserved. These features are illustrated in the outline sketches 

 (Figure 29). On the eastern side of Ndoi the sea has cut in the 



