ANDREWS : LIMESTONES OF THE FIJI ISLANDS. 15 



The Volcanic Islands. — These include islands like Kandavu, Taviuni, 

 Ngau, Nairai, Mbengha, Totoya, and Moala. Some of the islands, like 

 Muuia and Ovalau, are formed mainly of andesitic agglomerates (Plate 

 6) laid down rapidly in thick strata. In these beds occur layers of vol- 

 canic ash, finely comminuted, and filled with beautiful augite crystals. 

 Generally this agglomerate consists of angular blocks so firmly welded 

 in places as to render the junction of individual blocks almost indistin- 

 guishable. On Vanua Mbalavu layers of volcanic conglomerate occur 

 with rounded pieces, and this as much as 500 feet above the sea. Again, 

 as at Taviuni, on a large scale, and more or less on almost every island in 

 the group, streams of lava occur, the so-called " vata loa" of the natives. 

 On islands like Taviuni, Mango, Thithia, and Vanua Mbalavu, this 

 vesicular lava appears so distinct as to seem but the product of yester- 

 day (Plate 8). The basalt appears to have followed the andesite out- 

 bursts. Basaltic and andesitic rocks are seen everywhere on Taviuni 

 and Mango. Taviuni contains numerous craters, one being nearly 3000 

 feet above the sea level, with its rim fully 4000 feet above the sea. 



The Limestone Islands. 1 — These are very few in number and are small. 

 Vatu Vara, Waugava, Wailangilala, Katavanga, and Namuka are the 

 only ones I know to be wholly limestone. Fulanga, Karoni, and Aiwa 

 I believe may be (in the Lau division) added to this list. The Yasawas 

 are limestone, 800 feet high. With the exception of Fulanga, each 

 of the above named is extremely small. They consist of compact lime- 

 stones, very flinty in composition, and emitting showers of spai'ks when 

 struck with a large hammer. 



The Limestone and Volcanic Islands. 2 — These constitute a numerous 

 and important group. Besides the two main islands, it comprises Mango, 

 Vanua Mbalavu, Tuvutha, Naiau, Lakemba, Kambara, Thithia, and 

 Naitamba. These islands were, originally and generally considered, 

 lands possessing and presenting as many as six or seven terraces or indi- 

 cations of elevation and subsequent reef extension. Subsequently came 

 the upheaval which produced the volcanic agglomerates and lava masses. 

 These burst through and destroyed a great part of the cliff slopes, and 

 more or less filled the old inland lagoon areas. Such has been the case 

 particularly with Mango, Thithia, Lakemba, and Vanua Mbalavu. At the 

 latter island the force was so immense as to leave only the north and 

 south extremities intact, carrying the middle reef formations as high as 

 500 and 700 feet above high-water mark, leaving but a miserable meta- 



1 See A. Agassiz, /. c, p. 43. 



2 See A. Agassiz, /. c, p. 88. 



