GEOLOGICAL OBSERVATIONS IN FIJI. 11 



coastal plain which extends from 5 to 10 miles inland where it meets 

 an nplifted mass of marls, a former delta plain now carved into 

 mature hills 70 to 100 feet in height. The older delta plain slopes 

 gradually upward for 5 or 6 miles from its edge, until it rests uneon- 

 formably against the interior volcanic hills, at heights of (500 or 700 

 feet. 



These volcanic hills form the coast-line for the greater part of the 

 circumference of the island, except near its eastern border. Near the 

 shore the surface is usually maturely eroded, but farther inland 

 various irregular forms, called by the natives spines, thumbs, and twin 

 sisters, give the sky-line a very serrate appearance. 



The whole interior is characterized by irregular hills, though ([uite 

 extensive flats are sometimes found near the rivers. The rocks 

 forming the interior hills are frequently sandstones and marls, in 

 contrast to the volcanic rocks along the coast. 



The western and northern shores of the island are very irregular; 

 drowned valleys abound. Many of the valleys are filled with delta 

 deposits, and even small boats find difficulty in entering the river 

 mouths through the tangle of mangroves. 



In general the eastern side of the island is well watered; vegetation 

 is abundant. Gorgeous fern forests crown the hilltops, and the 

 higher peaks have giant trees hung with beautiful, trailing mosses. 



The western side is usually very dry; trees grow only along the 

 stream beds. An impenetrable growth of reeds covers the hills. 

 The rocks here are deeply lateritized and raAines cut the red and yellow 

 hill slopes. 



Western Viti Levu. 

 Singatoka District. 



The Singatoka river has incised a narrow valley in the mature hills 

 of western Viti Levu. Occasional flood-plains border the river, but 

 more often its banks are formed by volcanic hill slopes. In the in- 

 terior of the island, where loose marls and sandstones abound, flood- 

 plains are much more frequent than nearer the coast where andesitic 

 flows resist erosion. 



About 40 miles inland from the southwestern shore of Viti Levu, 

 the Singatoka river and its southern branches cut into a series of 

 plutonic rocks. The central portion of the mass consists of granite 

 and diorite, but near its border there is an ancient, rolling topog- 



