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



of patches and shoals. The barrier reef of Mbenga, including 

 four volcanic islands, is well marked to the south-east but much 

 broken to the north ; this perhaps is accounted for by the strong 

 tidal current which sets through the passage between this island 

 and Viti Levu. 



The mention of the foregoing facts is designed to point out the 

 great variability of the reefs in the Fiji Group and round even its 

 separate islands. It will further be evident that they bear little or 

 no relationship to the slope of the land, while the peculiarities of 

 some may be explained by the consideration of the currents and 

 winds prevalent in the group. The variability is so great indeed 

 that probably no single method of formation would explain all-. 

 The further consideration, however, will be deferred to Part VI. 



PART IV. 



The Raised Reefs of Fiji. 



SECTION I. Viti Levu. 



The main branch of the Rewa river is fed by several streams 

 from the" Kauvadra, a range of volcanic hills to the north of Vitu 

 Levu, which, rising from the coast of Viti Levu Bay, runs due 

 west for about 20 miles, whence it continues to the south with 

 spurs to the west, and divides the island into two halves. The 

 eastern half which is drained by the Rewa, has no long ranges of 

 hills, but is studded with isolated peaks, many of which are 

 characterised by having precipitous slopes and flat summits. 

 These are formed of limestone or of sandstone, in places obviously 

 overlying the volcanic rock, which is generally either a con- 

 solidated volcanic mud, or a vesicular lava. The hills above 

 Nailega on the Upper Rewa show clearly the characters of the 

 limestone hills, which reach their maximum height above sea- 

 level here ; the sandstone resembles the limestone in its slopes, 

 and it is hard to find the one rock without the other near at hand. 

 The hill of Koro Mbasanga, as a type, has a flat summit, which on 

 three sides is bounded by cliffs of 150 — 250 feet; on the fourth 

 the slope is extremely steep for 100 feet, but then there is a 

 broad flat terrace to which succeeds a slope at about 70° for 200 

 feet. Below these cliffs the slopes are gradual except towards the 

 Rewa, to which the hill falls at an angle of about 30° ; the height 

 above the river is about 700 feet, but, as the Rewa falls at least 

 200 feet below this, the total height is about 900 feet. 



