ANDREWS: LIMESTONES OF THE FIJI ISLANDS. 31 



feet above the rest of the island. This mass consists of a compact 

 coralline limestone, fairly horizontal, though eroded into pits and cracks. 

 This cap is of several acres' extent only. The sides are steep. On the 

 sea-side it presents a steep declivity to the water. It rests on the rim 

 of the central hollow some two miles in diameter. This, the second 

 " platform," is merely a thin coralline rim dipping sharply towards an in- 

 land crateriform cavity, some 250 feet below the level of the "platform." 

 The floor consists of weathered limestone, and is densely wooded. At 

 one end a gap occurs through which the material of the once continuous 

 platform appears to have been passed out in solution. Below this again 

 is another platform or terrace, also well marked (Plate 3, Figs. 3, 4). 



Vatu Vara has been described before. It is mentioned here again 

 merely to emphasize its height (Plate 25), its terraces and sea-erosion 

 at the 800 feet, 600 to 700 feet, 350 feet, 25 and 15 feet levels. 



Yathata is similar to Vatu Vara, especially in its sub-level cap (Plate 

 27) of several acres only and its well-defined steps or terraces here. 

 Another interesting point at Yathata is the comparative thinness of the 

 coral rock. 



Mba Vatu and Ngillangillah appear from the deck of a boat to consist 

 of huge coralline masses either as coral reef or reef debris (Plate 35). 

 This would give them a thickness of coral growth amounting to at 

 least 500 feet. By searching, however, an exposure was discovered of a 

 beautifully bedded limestone underlying the coralline rock. These strata 

 consisted of compact brown and yellow stone, apparently non-fossiliferous, 

 and reaching up through the mass to a height of nearly 300 feet. This 

 may occur as a base for the whole mass of Mba Vatu, but the coral 

 growths have seized upon it as it approached the surface, and terraces 

 have spread out from it, thus hiding it from view. The cliff of bedded 

 limestone stands out boldly amidst its coralline surroundings, and appears 

 to owe its exposure to-day to some past cliff rupture whereby the 

 encrusting coral growths were separated from the stratified rock. Three 

 miles away, and on the other side of the island, similar beds occur, but 

 now they are but 50 feet in height and have very little coral growth 

 attached to them. So that on this block 500 feet in height there is 

 at most not more than 200 feet of coral growth. 



Malatta. — To the south of Vanua Mbalavu, and 14 miles from Mba 

 Vatu, a small patch of limestone, about 100 feet in height, has escaped 

 the general disruption of the limestone by the volcanism. Here an 

 old line of beach erosion is found, tilted at 15° to the horizon, and 

 almost obscured by abundant redeposition of calcareous matter charged 



