476 THE CONTINENTAL ORIGIN OF FIJI, 



The quartzites outcrop strongly on the north-east bank of the 

 river, opposite the town of Togicedra, and continue to a point a 

 little past the town of Matainasou (altitude of river bed 300 feet 

 [aneroid]) (Plate xxxi., fig. li). Hence, for a distance of three 

 miles, no solid out-crops are met with, but the very slippery 

 nature of the path suggests soapstone-like tuffs again. Then 

 sandy tuff is met with in situ. 



Two miles below JJdu, at the junction of the AVainimala with 

 a large tributary, the Wailoa, there is a strong outcrop of highly 

 jointed tuff with a well marked dip of 16° towards N. 40*^ E. 

 The dip joints are about vertical. A second set dip S. 13° E. at 

 58" (Plate xxiv., fig. 6). 



The Wailoa (transl. = Black River) receives its name on account 

 of the material composing its bed. The rocks are mostly vesicular 

 olivine basalt, very rich in magnetite, and the latter mineral 

 forms the bulk of the sand. The steam holes in the lava are 

 lined with zeolites. For about one mile above Udu the rocks 

 consist of highly jointed, fine green tuffs of rather ancient 

 appearance, but above this point the river enters high volcanic 

 mountains. These are formed of basalt aiiolomerate, and are the 



CO ' 



source of the black gravel and magnetite sand mentioned above. 

 They appear to extend for a considerable distance to the north 

 and east. 



Above the village of Xabuacada, 2 J miles up stream from Udu, 

 quartz diorite again puts in an appearance, forming a rather 

 limited outcrop on the right (western) bank of the stream. The 

 basaltic mountains rise abruptly from the eastern bank in preci- 

 pices hundreds of feet in height. Again, at several points within 

 the next five or six miles, quartz diorite is met with here and 

 there. It occurs in the form of larsre an^rular boulders in the 

 beds of small streams cutting through agglomerate in situ. This 

 indicates the occurrence of the diorite in situ at no great distance 

 amongst the high country away to the south-west. 



This is the last point on the present section where plutonic 

 rocks appear in situ in large masses. 



