Or.ivKn. — Qeolorf]! of the Kcrmoflec hlands. 531 



History of Sunday Island. 



The Horald Islets may be looked upon as fragments of the wall of an 

 ancient crater of which the greater portion has been demolished by the 

 sea, and, though entirely detached from Sunday Island, I have no hesita- 

 tion in considering this crater the first to appear in the vicinity of Sundav 

 Island. There is no evidence to show that any land actually existed above 

 sea-level in this locality when the disturbance which resulted in the Herald 

 crater took place. The presence of littoral marine mollusca and corals, of 

 which many fragments are entombed in the beds of Dayrell and Ohanter 

 Islets, however, indicates shallow-water conditions, and, even if a fragment 

 of a once more extensive continental area did remain above the surface of 

 the ocean, whatever living forms existed on it were entirely destroyed by 

 subsequent volcanic eruptions, as no characteristic continental forms of life 

 are without doubt indigenous to the Kermadec Islands. 



The probable date of this eruption cannot, in a geological sense, be verv 

 remote. Those fossil molluscs which have been identified with tolerable 

 certainty all belong to living species, most of them still existing in Sundav 

 Island waters. One, Turbo argi/rostomus, is not knoMai to occur alive in 

 the Kermadec Group, but is found in Queensland and the Pacific islands. 

 Bearing in mind the fact that about 11 per cent, of the vascular plants 

 of Sunday Island are endemic, the newer Pliocene would perhaps be suffi- 

 ciently far back for the age of the Kermadec Islands. 



Contemporaneous with the formation of the Herald volcano a small 

 eruption occurred in Boat Cove, Sunday Island. This also was chiefly 

 submarine, as what now remains of the crater-walls consists of andesite 

 lava with many fragments of coral entangled (Nos. 22, 25). 



Meantime some yellow andesite tuffs (Nos. 13, 14) and a little lava were 

 being deposited under water further to the westward. These are now ex- 

 posed at D'Arcy Point and on Moumoukai within the crater ; the crumpled 

 older submarine beds at Hutchison Bluff also were perhaps deposited 

 about this time. The land, however, was rising, and a series of eruptions 

 followed, resulting in the formation of a third volcano, whose crater was 

 on the eastern side of Expedition Hill (the probable position of the inner 

 wall of this crater, which may be called the Expedition crater, I have 

 indicated by the broken oblique line in fig. 2). To this volcano I assign 

 practically all the lava on Sunday Island — namely, most of the flows and 

 dykes seen in section in the cliffs in Denham Bay, Scenery Bay, and 

 within the crater (rocks Nos. 21, 37, 40, 41, 9, 34). Over all was laid a 

 thick covering of andesite tuffs, from which evidently was derived the 

 material for the newer submarine series. 



After this copious outpour of lava the volcanic forces apparently were 

 suspended for a while, a boulder beach was formed along the shore-line 

 (which at one spot on the east coast and another in South Bay, co- 

 incides with the present shore-line), and the walls of the Expedition 

 crater were considerably denuded by marine and subaerial agencies. Next 

 followed a period of subsidence, denudation proceeding apace, resulting in the 

 deposition of the newer submarine series. (Plate XXV.) Meantime some 

 lava (Nos. 38, 39, 26) welled up and flowed in horizontal sheets in Denham 

 Bay, and later some dykes penetrated the tuffs in other parts. At the 

 base of the cliffs in Coral Bay I extracted a large TrocJim shell, belonging 

 to a species still living in Sunday Island, from a rough angular block of 

 lava. This could only have come from a lava-flow some height up the 



