464 Mr Gardiner, The Coral Reefs of [Mar. 7, 



Yaloi large limestone blocks are found strewn about, as if carried 

 up by the eruption which formed it. On the ascents there are no 

 sea shells, nor sea deposit of any sort ; indeed, this hill must have 

 been formed, not only subsequent to the formation of the lime- 

 stone, but also to its upheaval. It could not have been formed 

 simultaneously with the upheaval, or the precipitous limestone 

 cliffs, cut off by its lower slopes from the sea, would have had no 

 existence. 



From the cliffs the land slopes in everywhere gradually towards 

 the centre of the island, which forms a broad plateau about 100 

 feet above the sea. The slope is, however, sometimes uneven, 

 forming precipices 20 — 30 feet high. On the plateau itself are 

 many small hills, rising nearly to the level of the rim, with very 

 steep walls, and some springing out almost like buttresses from 

 the rim itself. The natives affirm that in this plateau there are a 

 number of deep holes, in which salt water is found and tidal 

 influences are felt. The rim is somewhat broken as if by dykes 

 40 — 100 yards across ; its breadth varies greatly, but generally 

 the ridge is at least 100 yards across. 



Round the whole island the reef is fringing and narrow with 

 a channel, 1 — 2 fathoms deep, for some distance to the south-west 

 of Delai Yaloi ; north-west of this hill and off it, it is merely 

 represented by a few sunken patches growing up 1 . 



Vanua Mbalavu, the largest island of the Exploring Group (Fig. 

 8), is of mixed origin. Within the barrier reef, enclosing the group, 

 islands of all the three kinds are met with ; of these Thikombia-i- 

 lau, Sovu, Avea and Munia stand quite apart, while Susia and 

 Malatta really continue the main island to the south and east, the 

 three being surrounded by the same inner fringing reef. Thi- 

 kombia-i-lau standing 550 feet, Sovu 230 feet, Avea 600 feet, and 

 Malatta 420 feet high, are all of the same dense limestone as 

 Fulanga, while Munia, 950 feet high, consists entirely of erupted 

 rock. Susui, 430 feet high, to the east of Malatta, has its west end 

 of limestone much undermined by the sea with precipitous cliffs ; 

 to the east this passes gradually into volcanic rock with more 

 gentle slopes. 



Opposite Avea on Vanua Mbulavu is a hill, Koro Mbasanga, 

 930 feet high. From this the island runs west for 6 miles and 

 south for 8, its average breadth being about 2 miles. North-west 

 at the base of Koro Mbasanga is a deep creek, the rock of which 

 on the west side is limestone, precipitous and much undermined, 

 while on the other side the shore is formed by the slopes of this 

 hill, the rock of which is volcanic. The two rocks join here with 

 no sharp line of demarkation except in the vegetation, the lime- 



1 The reef in Fig. 7, which is taken from the chart, is not quite accurately 

 represented. 



