ANDREWS: LIMESTONES OF THE FIJI ISLANDS. 17 



occur. These have eappings and bases of so-called " soapstone." This 

 alternating structure is still more marked along the Tamavua River, 

 near Suva, where many successive layers of soapstone and of limestone 

 are visible in one exposure (Plate 39). Terraces and beaches are not 

 distinct topographical features of the larger islands, as they are in the 

 members of the Lau Group. 



With respect to the reefs surrounding the islands of the Fiji Group, 

 we may notice that on the southwestern portion of Viti Levu the reefs 

 are fringing. 1 Strange to say, the Singatoka River, large as it is (Plate 

 3 a ) and bringing down a volume of fresh water comparable with that of 

 the Rewa River, causes no sensible diminution of the fringing reef. 



There is one small passage only, a very few yards in width, through 

 which the escaping water at low tide pours out at the rate of six to nine 

 miles per hour. Even this passage has a reef base nearly awash at 

 low tide. For a distance of seventy miles towards Suva the fringing 

 reef continues. But beyond this point, in a direction extending towards 

 Ovalau, the reefs gradually recede for miles from the shore. 



Vanua Levu is surrounded by an even greater mass of reef. 2 



Topography of the Smaller Islands. 



The islands of the Lau Group and such islands as Taviuni and Kandavu 

 present the appearance of huge sloping lava flows as at Taviuni, as higher 

 pitched slopes at Ngau, Nairai, and Vanua Mbalavu ; or, again, as solid 

 limestone masses rising from the sea. These mural fronts are roughly 

 subcircular in shape, are some 400 or 500 feet high, and may exhibit 

 vertical cliffs looking out upon large skirting sand flats, or, again, they 

 may exhibit a slope suggestive of an inverted cup or truncated sugar- 

 loaf. This shape is of general occurrence, its uniformity all over the 

 group suggesting it to be the original slope of the reef before elevation. 



Terrace structures and upraised lines of ancient sea erosion cut into 

 the cliff's are also a frequent feature of Lau scenery. A detailed exami- 

 nation of Mango's topography and more or less complete notes on other 

 islands visited is furnished here as a supplement to these general 

 remarks. 



Mango (Plates 1, 2, 9-17). — This island is subcircular in shape, 

 and as seen from the sea appears like a huge mass that has been 

 upheaved about 500 feet above the level of the sea. The summit 

 seems to be a vast flat broken in two places by great dome-structures 



1 A. Agassiz, I. c, pp. 110, 118. 



2 A. Agassiz, I. c, p. 121. 

 vol. xxxviii. — no. 1. 2 



