528 Transactions. 



referred to in this paper as the " newer submarine beds." The upper beds 

 are irregular, and doubtless of subaerial origin. They are composed almost 

 entirely of andesitic pumice, including fragments of lava rocks. At the 

 summit of Mount Junction (472 m.) a small angular fragment of hornblende- 

 granite was collected, and high up on one of its southern spurs, over 200 m. 

 above sea-level, a larger boulder was noticed. 



In the cliffs beyond the beach the basalt-flow is seen to thin out and 

 finally disappear. Entire cross-sections of other flows are also exposed. 

 They are horizontal, of nearly uniform thickness for most of their length, 

 and taper at both ends. A specimen from one of these beds proved to be a 

 dark-coloured augite-olivine-andesite (No. 26). At the base of the cliffs is 

 a boulder beach composed mainly of fragments released from the volcanic 

 tuffs above as they weather away. At one spot was observed a large water- 

 worn boulder of hornblende-granite about 50 cm. long. 



The sections of Big and Expedition Hills as exposed to view in Denham 

 Bay show a series of lava-flows dipping at an angle of about 5° to the north- 

 west. A specimen from one of these is a grey basalt (No. 37) ; another 

 from a flow lying above is a dark compact andesite (No. 21,. Above the 

 lava-flows are volcanic tuffs. 



A large landslip which occurred in Denham Bay some six years ago 

 exposed a section of tlie cliff up to a height of 300 m. The lower part of 



Landslip Big Hill Expedition Hill Crater Ridge Ml. JiukH' 



Hcmortlal laM'flou's ^^^ Newer submarine tuffs ^-jf^I-~r 

 Inclined lava-flows ^ifHSH Subaerial luffs ^fi^Sj=^ 



l<'it!. ?. — Cliffs in Df>nham Bay, Sunday Island. 



the cliff, however, is covered by the fallen material. The section exposed 

 shows no lava-flows, but a series of irregularly stratified beds of andesitic 

 tuffs, not pumiceous, but containing angular fragments of lava rocks. 

 These beds have a northerly dip. Further on a few beds dip at a high 

 angle — about 40° — as though they had been undermined and slipped down : 

 they are adjacent to the next-described submarine series. 



At the north end of Denham Bay the series of beds corresponds in part 

 to those at the south end. At the base is a horizontal flow of andesitic 

 basalt (No. 39), then about 60 m. of evenly stratified submarine tuffs covered 

 by subaerial tuffs, which, however, are not pumiceous. Below the lava at 

 one place a little tuff containing some decomposed wood is exposed. 



The extreme point of Hutchison Bluff is quite a bare cliff .300 m. high. 

 It consists entirely of irregular beds of andesitic tuffs. These tuffs consist 

 of a coarse-grained gritty rock, which weathers quickly, containing small 

 fragments of lava. On the north coast, from the Terraces (which cover 

 the bases of the higher cliffs) to near the bluff there are two distinct series 

 of beds, the upper ones superimposed on the eroded surface of the crumpled 

 lower beds. The upper beds are composed entirely of andesitic tuffs (with 

 no pumice), and, dipping generally but slightlv to the westward, pass 

 bevond the lower beds near Hutchison Bluff". The lower beds consist of 



