136 Tranmctions. 



North-westward the Plateau extends in an immense submerged 

 ridge, which may be called the " Lord Howe Island Ridge," and 

 joins or almost joins the New Caledonian Plateau. The deep 

 channel which runs along the south-western side -of New Cale- 

 donia may extend northwards between the D'Encrecasteaux 

 and Chesterfield Reefs, thus cutting off the New Caledonian 

 Plateau from that of New Zealand by a narrow channel ; but 

 this is not very probable, and a few soundings are needed here 

 to decide the point. 



This great ridge is the most striking feature of our Plateau, 

 and it has profoundly affected the character and distribution 

 of the fauna and flora of New Zealand — a great stream of life 

 having come in this way. 



At the southern extremity of the Lord Howe Island Ridge, 

 and lying to the north-westward, there are two smaller ridges, 

 that lying farthest north being the extension of what is now 

 known as the Auckland Peninsula. Between these ridges lie 

 two valleys or depressions, in which, no doubt, large rivers 

 flowed at the times of elevation. 



The great backbone ridge of New Zealand, with its divergent 

 ranges, must have presented a truly grand appearance during 

 the periods of elevation — the beginning of the Tertiary era and 

 early Pliocene — when the land stood five or six thousand feet 

 higher than now, with its vast snowfields and glaciers grinding 

 out the great valleys and fiords, and forming the moraines 

 which lie scattered about the country. 



North of the main body of the Plateau and east of the Lord 

 Howe Island Ridge a large depression known as the " Gazelle 

 Basin " lies between New Zealand and the Fiji Islands, and 

 further eastward again, beyond the Kermadec Ridge, the 

 " Aldrich Deep " culminates near the Kermadecs at a depth of 

 over 5,000 fathoms, plumbed by Captain Aldrich. Its western 

 boundary is an immense mural escarpment, running southward 

 from the Tonga Islands past the Kermadecs, and down the 

 eastern side of the North Island towards Cook Strait, where it 

 turns abruptly eastward to the north of the Chatham Islands. 

 On the west our Plateau is separated from Australia by the 

 " Thomson Deep," which is evidently one of the great prim- 

 ordial depressions of the earth's crust, and accounts for the 

 fundamental difference between the animals and plants of 

 Australia and New Zealand. Eastward from the Australian 

 coast-line the sea-bed rapidly plunges down to a great depth 

 (2,600 fathoms), and then rises gradually in a long undulating 

 slope to New Zealand. 



The evidence of the former great extension of New Zealand, 

 and of the vast changes that have oc(nirred in this region, as 



