BY W. G. WOOLNOUGII. 471 



low hills of soft " soapstone"-like andesite tuffs covered with low 

 ^' reeds," giving the hills a smooth appearance and a light 

 yellowish-green colour. 



A little above this point a volcanic rock of a type not met 

 with in the Waidina valley puts in an appearance. This is a 

 hornblende andesite with well marked hornblende prisms. The 

 shingle in the river is coarse and is made up largely of typical 

 diorite and quartz diorite. 



The river does not very closely follow the boundary of the 

 agglomerate hills to the east, but in a general way it may be said 

 to do so. The banks are composed of bedded tuffs, mostly about 

 horizontal, but often with very marked dips in various directions. 

 The tributaries which enter the river come from the east, and 

 contain pebbles of andesite and andesite agglomerate. Much of 

 the tuff is full of small-but perfect augite crystals. 



The mountain Nabui (Plate xxvii., fig. 10) is about one mile 

 from the river to the east. It appears with the glasses to consist 

 of agglomerate, but this is by no means certain. Its marked 

 columnar structure is rather suggestive of solid andesite, and its 

 shape of a large volcanic neck. It was, for me, inaccessible, so 

 the point had to be left undecided. A creek coming from the 

 direction of the mountain brings down agglomerate (Plate xxix., 

 fig. 12), solid andesite and fine tuff. 



Above this point the course of the river lies amongst the rugged 

 agglomerate hills. The boundary of these hills sweeps away in 

 a long curve to the west of north for a considerable distance 

 from the point where the river leaves them. The boulders which 

 litter the stream bed are of large size, up to 4 feet in diameter, 

 and subangular in shape, so that the plutonic rock may be in situ 

 somewhere close at hand. Very possibly there is an outcrop to 

 the west."^ 



* 1 did not notice any considerable tributaries about this part of the 

 river, though two are shown on the map. This is explained, perhaps, by 

 the fact that the track cuts across one or two low spurs to avoid long bends in 

 the river, and the vegetation is so thick that it is impossible to see more than 

 five yards in any direction. The largest diorite boulders appear to be on the 

 western bank. 



