From Cook Strait to Tonga Tabu. 99 



Ocean by a submarine plateau which rises to within 1000 fathoms 

 of the sea surface, and unites Australia, New Zealand, New 

 Caledonia, and Papua into a single area of elevation, it may be 

 considered as forming a bight of the Southern Ocean (Plate 2). . 

 The cross section of this area presents the not unfrequent con- 

 trast of deep soundings and a comparatively rapid fall of the sea- 

 bottom along its western boundary, and of shallow soundings 

 and a slowly rising bottom towards the east. The western half 

 of the basin is occupied by an area of depression of more than 

 2500 fathoms, or about three miles in depth, extending from the 

 south point of Tasmania along the east coast of Australia as far 

 as Great Sandy Island, where the coast turns towards the north- 

 east. The eastern half forms a broad plateau, which ultimately 

 rises above the level of the sea under the name of New Zealand. 



A branch of the South Pacific Equatorial Current, after 

 passing to the southward of the Fiji Islands and New Caledonia, 

 strikes the Australian coast near Great Sandy Island, and, 

 bending round, flows as a surface-current, known under the name 

 of the East Australian Current, close along the shores of New 

 South Wales. With the exception of this current, the whole of 

 the basin between Australia and New Zealand is occupied by a 

 branch of the South Australian Current, which, crossing the 

 basin in a north-easterly direction, carries a portion of the East 

 Australian Current along with it, and divides into two 

 branches, one returning southwards along the west coast of 

 Middle Island, while the other flows round the North Cape and 

 probably down the north-east coast of North Island. 



A comparison of the isotherms at Stations 165 and 166 west 

 of New Zealand, and at Stations 168 and 169 east of the 

 latter, seems to show that at the time of the " Challenger's " 

 visit, which was in the winter of the southern hemisphere, the 

 whole plateau of New Zealand was swept by a current from the 

 south-west, whose temperature was somewhat raised through 



