ANDREWS : LIMESTONES OF THE FIJI ISLANDS. 13 



General Geological Structure- 

 The Larger Islands. 



Viti Levu. 1 — In this, the largest island in the Fiji Group, nay researches 

 were confined to an examination of the Suva district, of a ten-mile strip 

 stretching from JSTandronga Singatokawards, and a short excursion ex- 

 tending over some thirty miles up the large. Singatoka River. Viti Levu 

 and Vanua Levu stand out distinctly from all other members of the 

 group, and bear the imprint of a hoary antiquity compared with the 

 volcanic islands of Taviuui, Ngau, and Kandavu, as well as with 

 the limestone islands constituting the Lau division of the Fiji area. Pro- 

 ceeding along the banks of the Singatoka River, interesting outcrops of 

 limestone of high dip were observed. Volcanic agglomerates of porphy- 

 rite and masses of andesite rock, apparently identical with similar rocks 

 in the younger islands, have burst through the more ancient sedimentary 

 rocks. The volcanic rocks exhibit various stages of decomposition. The 

 hills roll, cone after cone, behind each other to a height of 3000 feet, and 

 the main road follows the curves of the lower hill shoulders, thus reveal- 

 ing numerous dykes, and thin beds of strata, dipping at high angle, which 

 are crossed again and again in a few hours' walk. In places these strata 

 contain a bright green cherty rock, interbedded with softer brownish 

 layers. 



The Stratified Rocks. — Argillaceous rocks and soft crumbling beds 

 occur with high dip. They are brown in color and at times effervesce 

 with acid. 



The Dolomites. — These appear to underlie the strata just enumerated. 

 They are principally centred in an immense block overlooking the river. 

 They consist of two hills 1000 and 1500 feet respectively above the 

 river, and reaching, in the case of the smaller one, into the water at the 

 base. They are practically perpendicular, having a slope of 85° in places 

 aud 90° in others, and are uniformly hard and homogeneous in character 

 from base to summit. They are tunnelled with caverns. To the eye or 

 ordinary lens they are non-fossiliferous. Acid scarcely causes any effer- 

 vescence. According to report this rock is found along a line roughly 

 northwest and southeast, but I saw no trace of its development else- 

 where. 



Of the evidently later limestones that more or less fringe the shore of 

 the island near the mouth of the Singatoka River, one notices, com- 

 1 See A. Agassiz, Bull. Mus. Comp. Zool., 1899, Vol. XXXIII. p. 110. 



