Geology.] 



SUBANTARCTIC ISLANDS OF NEW ZEALAND. 



687 



found on the south-west coast, between Mount Dumas and Mount Yvon Villarceau. 



The tuffs are of submarine origin, for they contain marine fossils in at least three 



places — namely, (1) near 

 Terror Point, in Perse- 

 verance Harbour; (2) at 

 the foot of Mount Du- 

 mas ; (3) between Mount 

 Dumas and Mount 

 Eboule. Apparently 

 only the first of these 

 localities was visited by 

 Filhol. My knowledge 

 of the other localities is 

 due to the kindness of 

 Mr. Chambers and Mr. 

 Des Barres, who col- 

 lected fossils for me 

 from them. The thick- 

 ness of the tuffs is about 

 500 ft, on Mount Dumas 

 and about the same on 



Fig. 4. — Mount Menhir, Campbull Island, fkom the East. "the SCaward laCC 01 



Mount Eboule. 

 Upon the tuffs volcanic lavas are found. Four lavas can be clearly seen on 

 Mount Dumas and Mount Honey. They lie almost horizontally, though on Mount 

 Dumas there is a distinct 

 dip to the eastward, as 

 is clearly seen in Filhol's 

 sketch of the mountain. 

 The lavas stand out as pro ■ 

 minent terraces on the hill- 

 sides, as they resist erosion 

 strongly compared with 

 the relatively soft scoria - 

 beds which separate them. 

 The lowest lava - flows 

 are trachytes, the upper 

 are dolerites or basalts, 

 and there are others of 

 intermediate composition. 

 Some of the upper scoria- 

 beds were deposited under 

 subaerial conditions, for 

 the fragments are full of 

 gas-pores and are dark 

 red in colour. Dykes are 

 very numerous in all the rock-systems except the gabbro, in which none were seen ; 

 and they are far more numerous in the sedimentary rocks than in those of volcanic 



Fig. 5. — Peat 8 ft. thick, uesting on Bueccia, uetween Mount Pakis and 

 Mount Dumas, Campbeli, Island. 



