GEOLOGICAL OBSERVATIONS IN FIJI. Z.) 



diorite associated with sandstone were found. These rocks niiist he 

 in place not far inhmd, hut lack of time forbade a search for outcrops. 

 Volcanic rocks, carved into mature hills, form the shore-line for 4 

 or 5 miles east of the Navua delta plain. An outlying island, Nangara, 

 10 to 15 feet in height, marks the beginning of the coastal-plain marls. 

 The sediments of the uplifted coastal strip occur at intervals, as jutting 

 points of land or off-shore islands, for 14 or 15 miles to the east, or 

 until the large area of marls forming the eastern side of the island 

 near Suva entirely shuts off the volcanic rocks from the coast. 



The short coastal rivers, cutting across the narrow coastal plain, 

 have incised deep, subsequent ^'alleys betw^een the marls and the vol- 

 canic rocks just at their contact. This erosion, followed by a slight, 

 recent submergence, has produced a considerable number of off-shore 

 ■ islands. Both processes have rendered it difficult to locate the contact 

 of the coastal sediments with the interior volcanic rocks. 



From the island of Nangara eastward, the coastal sediments rise 

 higher and higher on the slope of the vokanic hills until at Tholo-i- 

 Suva, 10 miles from the southeastern side of the island, they are found 

 at an elevation of 700 feet. Along the western part of this strip of 

 land, they do not, however, form the entire coast-line, since a number 

 of the rivers have cleared the marls away from their mouths. The 

 bay-heads usually show outcrops of volcanic rocks, while the project- 

 ing points and many of the islands are composed of marl, often inter- 

 bedded with lenses of coralliferous limestone. 



In order to study the relation of the uplifted coastal sediments to 

 the interior volcanic rocks, several trips were made up the small 

 rivers, emptying into Suva Harbor at the extreme southeastern end 

 of the island. All of these rivers cut both the uplifted marls and the 

 volcanic rocks upstream. 



At the mouth of the Visari, the westernmost of these small streams, 

 the marls dip 20° N. E. and overlie a conglomerate composed of 

 boulders of diorite and granite.. That the conglomerate is older 

 than the surrounding andesite is shown farther up the river, where it 

 disappears beneath a series of andesitic flows. An old rhyolitic 

 breccia is associated with the conglomerate in a way which could not 

 be determined. It is probable that the conglomerate was eroded 

 from the interior granites before the great submergence during which 

 the marl and limestone of the folded series of central Viti Levu were 

 deposited. 



The lower course of the Visari is very quiet, but at the contact of 

 the conglomerate and the andesitic flows, 5 or 6 miles from its 



