28 



FOYE. 



cones were laid down beneath the sea. After later uplift the vol- 

 canoes were so deeply eroded that their central agglomerates are now 

 exposed in abrupt cliffs, and the surrounding ash beds have been 

 carved into hog-back ridges. Certain interbedded lava flows were 

 eroded, to form fingering points extending seaward. 



Following this period of erosion, the island subsided and coral- 

 liferous limestones were deposited about the spur-ends of the hills 

 extending seaward. These deposits have been largely swept away by 

 subsequent erosion. They are known to occur on the northern 

 side of Vanua Levu only at one locality, three miles west of the 

 Lambasa river near its mouth. Here, as shown in the sketch (Figure 

 12), coralliferous limestones lie in a valley cut in the andesite. The 



Figure 12. Cross-section of an Elevated Coral-reef near Lambasa, ^'anua 

 Levu. 



White — volcanic rock. Dotted — basal conglomerate. Black — ele- 

 vated coral reef. 



limestone is quite different in appearance from that found elsewhere 

 in the group. It has a paste of light, slate-colored marl. On weather- 

 ing, the silver-gray of the marl changes to cream-white. A shell- 

 limestone, with occasional small pebbles of andesite, umlerlies the 

 deposit, wliile a yellow sandy marl caps it in places. 



During the period of crustal stability following the subsidence, 

 continiu'd (Hssection of the andesite produced a series of wide valley 

 Hoors dotted with residual hills extending far inland. The edge of the 

 central plateau of agglomerates and fossiliferous tuffs retreated farther 

 and farther towards the interior and peaks were carved by erosion 

 from the disappearing mass. The valley peneplain thus fornictl is 

 now found at an elevation of 12.") to l')!) feet above sea-level, and may 



