GEOLOGICAL OHSERVATIONS IN FIJI. 13 



low, in contrast with those of the folded sediments, it was inferred 

 that the andesitie agglomerates were more recent than the marls 

 and sandstones of the interior. 



Seven miles from the coast, near Narata, a boulder conglomerate, 

 with pebbles and boulders 12 to 14 inches in diameter, was found. The 

 boulders are largely of andesitie material, very rarely of limestone. 

 There is little paste in the conglomerate but occasional layers of 

 gravelly sandstones are interbedded with it. These beds dip 8° to 

 10° S. While no contacts were seen, it is reasonable to suppose that 

 the conglomerate was eroded from, and overlies, the agglomerate and 

 limestone formations which outcrop on the north. From this point 

 southward, sedimentary rocks occur which have the same general 

 character as those found at Narata, save that the size of the grain 

 becomes smaller and smaller as one approaches the sea. At Yalava, 

 gravel deposits appear; at Tusuirewa, three miles from the mouth of 

 the river, the rocks exposed are marls and sandstones. All these 

 deposits have low dips and form part of an old, uplifted coastal plain. 



Near the mouth of the river and for several miles along the coast on 

 either side, there is a series of maturely eroded hills of deeply lateri- 

 tized andesitie flows and agglomerates. About these andesitie masses, 

 the sandstones and marls of the ancient coastal plain were deposited 

 and later were partially eroded away. At present, coral limestones, 

 which were formed in the quieter waters off the ancient shore-line, 

 cover the hills near the sea; farther inland sandstones and marls 

 occur. 



Coral limestones, interbedded with marls and fine conglomerates, 

 are found along the coast for 15 or 16 miles on either side of the 

 mouth of the Singatoka river. The limestones form lenticular beds 

 which often pinch out abruptly. They appear at elevations up to 

 150 feet and are extensively eroded. 



About 12 miles west of the Singatoka, at the little town of Na 

 Sana Sana, a diabasic dike, five feet in width, cuts the limestone. 

 There has been igneous activity, therefore, subsequent to the forma- 

 tion of the narrow coastal plain. 



The accompanying sketch (Figure 2) illustrates the topography at 

 the mouth of the Singatoka river. A low point of coralliferous lime- 

 stone juts out from the eastern bank. The limestones rise 75 feet 

 on the side of an andesitie hill, a c^uarter of a mile back from the 

 shore, from which the sketch was made. To the west, rolling sand 

 hills, approximately 150 feet in height, extend for two or three miles 

 along the coast. The dunes are travelling westward. 



