53l2 Transactio7is. 



cliff. The amount of subsidence can be gauged by the thickness of sub- 

 marine tufis — namely, about 60 m. These submarine beds were covered 

 with a considerable thickness of andesite tuffs with irregular bedding, pro- 

 bably ejected from the Denham Bay crater. Upheaval afterwards took 

 place, and has continued till the present time, the island meanwhile being 

 considerably reduced by the action of sea and rain. 



An eruption resulting in the present large, or Sunday, crater was the 

 last serious attempt of the island to add to its size. A violent outburst 

 forced a way through the lava-flows forming the northern slopes of the 

 Expedition volcano. No molten rock came to the surface in this new crater ; 

 only pumice tuiis containing numerous fragments of lava rocks and fewer 

 of hornblende-granite and andesite-pitchstone (No. 2). The lava-streams 

 of the northern slopes of the Expedition volcano were shattered to frag- 

 ments, some of which, 2 m. or 3 m. in diameter, were hurled up as far as 

 Fleetwood Blufi. The pumice tuffs ejected from this crater form, as far as 

 I can judge, the whole of the lower northern portion of the crater-rim, 

 Mount Campbell and the upper part of the crater-rim resting on the 

 extinct Expedition volcano. The Terraces, which originally must have 

 joined the crater and extended for a considerable distance out to sea, were 

 also the product of the Sunday crater. In describing their structure I 

 have already pointed out that the largest boulders freed by marine denuda- 

 tion at Fleetwood Bluff are identical in external appearance with specimens 

 (Nos. 9, 34) from the great ruptured lava-stream within the crater. It is in 

 the ejectamenta of this crater alone that fragments of hornblende-granite 

 were observed. 



The struggles of the dying volcano of Sunday Island had not yet quite 

 ceased, for an eruption on a small scale occurred within the very walls of 

 the large Sunday crater, and resulted in the formation of a small pumice 

 cone, of which Green Lake occupies the centre. The fine-grained tuff 

 (No. 32) containing bombs is the product of the Green Lake crater. 



Recent Volcanic Activity on Sunday Island. 



Two eruptions have been recorded since the discovery of Sunday Island.* 

 One occurred in 1814, and is recorded in the Sydney Gazette of the 17th 

 September of that year (Smith, 1896) ; the other took place about the year 

 1872, and of this an account was printed in the Southern Cross (Sterndale, 

 1884; Smith, 1888, p. 337). 



There are still many signs of volcanic activity on Sunday Island. 

 Earthquakes are fairly frequent, and are usually followed l)y small land- 

 slips. Four rather severe shakes and many shght tremors were experienced 

 on Sunday Island during the first ten months of the year 1908. 



Fumaroles occur in several parts of Sunday Island. 



Macauley Island. 



Macauley Island, distant 109 km. from Sunday Island, is somewhat 

 circular in outline, and entirely surrounded by cliffs, which can be scaled 



* Mr. H. I. Jensen (Proe. Linn. Soc. N.S.W., vol. 31, p. 661) states that a violent 

 eruption oceurred in the Kermadec Islands in 1902. This may be a slip of the pen, as 

 the vegetation in the erater has apparently never been disturbed sinee the new growth 

 after the outbreak of 1872, anil the inliabitants did not mention an occurrence, thougli I 

 believe Sunday Island may have been deserted about the year 1902. 



