OCEAN CONTOURi^, S.W. PACIFIC. 439 



phases. Here, too, Mawson mentions immense subsidences along 

 fault lines, by which the present separation of the islands has been 

 effected. 



Evidence of elevation within comparatively late times from a 

 geological standpoint is to be foimd in many other islands within the 

 South-west Pacific region. In the Tonga Islands Lister states that 

 raised coral terraces are at Vavau and Eua 1,000 ft. above sea level. 



Among the Cook Islands Mangaia shows a " makatea" of raised 

 coral. The same is seen at Mauke, while Niue consists entirely of 

 raised coral, in which at least three terraces marking different stages 

 of elevation ai-e to be clearly seen. Darwin does not claim these 

 islands as within his area of tjqiical subsidence. His observations on 

 the coral growths around them led him to state mereh^ that tliey were 

 not areas of rapid subsidence. 



Tahiti on the other hand is classed by Darwin as a subsiding 

 island, though several of the descriptions he quotes show that the 

 coral reef is in places close to the sliore, and at other times there is 

 only shallow water between it and the shore. On the other hand 

 Dana states that any submergence of Tahiti would form deep inlets 

 striking far into the land. We have also a description by Guilleinard 

 and Keane wdiich mentions the flat land extending round the island, 

 and the circular terraces that are to be seen above it. 



The present land forms of Tahiti thus evidently suggest recent 

 elevation, though it must be remembered that Dana distinctly pro- 

 nounced against tliis view, except, perhaps, at Bola-bola, but even 

 there he regards any elevation tliat may have occurred as far from 

 recent. 



In New Zealand the elevation and volcanic action which closed 

 the Miocene appear to have been long continued, and the land rose to 

 a level distinctly higher than the present one. The evidence for this 

 is to be found in tlie numerous drowned valleys wliich were eroded in 

 Miocene sediments and volcanics alike in so many places. The rias 

 of the Auckland neighbourhood, the harbours of Whangaroa and 

 Whangarei in the North, Aotea and Kawhia fui-ther South, all 

 traverse Miocene rocks. At Wanganui the artesian wells show that 

 the true bed of the river is at least 600 ft. below the present sea level, 

 though the rocks 100ft. above sea level contain Pliocene fossils. 



In the South Island Otago Harboiu' is eroded in Miocene rocks, 

 while on the western side Presentation Inlet passes through Miocene 

 rocks at its entrance, and at the extreme north of this coast the West 

 Wanganui Inlet is entirely svirrounded by cliffs of Miocene rocks. 



In Campbell Island there are several drowned valleys in rocks 

 that are almost certainly of the same age, and the same is true of 

 the Auckland Islands, but in these islands, as at Presei-vation Irdet, 

 it is possible that the valley floors were eroded by ice below the sea 

 level of the period of erosion. 



These same facts may be quoted to prove that this great period 

 of elevation was succeeded by a depression, for the full amount if 

 which the later movement of elevation has not yet compensated. 



No available descriptions appear to prove a similar downward 

 movement in other South Pacific islands. In Fiji the elevation has 

 been described as continuous by Woolnough, and in the New Hebrides 



