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BY W. G. WOOLNOUGH. 477 



From Viniiwaiwaivula to Nubumakita the track passes over 

 hills rising to a height of 1550 feet (aneroid) above sea-level. 

 These hills are composed exclusively of yellowish-grey soapstone- 

 like tuffs. Near Nubumakita (1000 feet) these tuffs dip uniformly 

 and at gentle angles in a general north-easterly direction, and 

 exhibit very perfect sphheroidal weathering. These tuffs have a 

 very wide extent over this part of the island, and form the 

 predominant feature all the way to the north coast. 



At Nasoqo, nine miles (about N.W.) from Nubumakita, an 

 interesting section is met with. About half-a-mile up the stream 

 (head waters of the Wailoa) there is a marine cotiglornercUe. No 

 underlying rocks were observed, nor were granite or diorite 

 boulders met with in the stream above the point of outcrop of the 

 conglomerate. The latter consists of a yelloA\ ish sandy base of 

 tuffaceous origin, containing tiny augites. Through this base are 

 scattered rather sparsely well rounded pebbles up to four inches 

 in diameter. Some of these at any rate consist of quartz diorite 

 fairly coarse in grain. The marine origin of the formation is 

 proved by the occurrence of shells. Unfortunately these do not 

 appear to be numerous, and I did not find many. Amongst other 

 shells which I did obtain is an undoubted Cooins, but too much 

 damaged to determine specifically. The height above sea-level of 

 this bed is 790 feet (aneroid). It is overlain by a fairly thick 

 bed of fine, mudd}^ blue-grey tuffs estimated at about 50 feet 

 thick. A short distance back from the stream, cliffs of coarse 

 augite andesite agglomerate rise several hundred feet in height. 

 Huge boulders of this agglomerate are met with in the creek. 

 The rock is dark in colour, and distinctly more basic in character 

 than the augite andesites of the southern portion of the island, 

 though probabl}^ not quite so basic as those near Udu mentioned 

 above. The base is remarkable for containing, quite abundantly, 

 fairly large and perfect augite crystals. 



Cutting through the grey muddy tuff" overlying the conglome- 

 rate is a dyke of basic rock. This is somewhat irregular in shape 

 and direction, as might be exjDected from the softness of the 

 intruded rock, but its occurrence is important as giving some idea 



