WoBLEY. — On the Geology of Nelson. 415 



2,600 fathoms. Owing to an insufficient number of soundings, 

 the contour of the plateau has not been determined, but it is 

 supposed to extend as far eastward as the Chatham Islands ; 

 while to the westward, especially in the south-west, the line of 

 the plateau is almost identical with the coast-line. The coast- 

 line itself also bears evidence of subsidence. Those who have 

 travelled only from here to Wellington have probably noticed 

 how the curve of the hills reaches almost to the water's edge. 

 This shows that the land has had a downward movement in 

 recent geological times. If the land had been stationary we 

 should have had high cliffs, caused by the erosive action of the 

 sea, presenting themselves ; or, if the land had been rising, 

 extensive sea-beaches would have fringed the coast. Small 

 islands, near the coast, like Pepin Island, D'Urville Island, 

 Arapawa Island, and Kapiti Island, also bear evidence of the 

 subsidence of the land. These islands are but the tops of 

 hills which once formed part of the mainland. A glance at 

 the map of New Zealand also leads us to conclude that New 

 Zealand had once a more extensive land-area. The coast-line, 

 as you will see, is characterized by a few bold headlands with 

 extensive bights lying between. These headlands are com- 

 posed of hard rock which has been better able to resist the 

 action of the sea, while the places into which the sea now 

 flows, forming extensive bights, once formed part of the dry 

 land. The remarks about the islands in Cook Strait will also 

 apply to the Barrier Islands, White Island, and Stewart 

 Island. 



Let us suppose, then, that the submerged plateau of which 

 we have spoken was once high above the water ; that the con- 

 tour of that plateau was the boundary of an extensive conti- 

 nent which extended from East Cape in the North Island to 

 Shag Point in the South Island : then the place which we now 

 call Cook Strait — I mean the narrow part — was merely a 

 pass in the mountain-chain ; and the place which we now 

 know as Tasman Bay was a broad valley, through which 

 probably flowed a large river, the upper reaches of which 

 are represented by the streams wdiich at present drain into 

 the bay. 



The greatest depth of Tasman Bay does not exceed 

 50 fathoms, while a great part of it has a depth of less than 

 50ft. When the submerged plateau, then, stood above the sea 

 some hundreds, or probably thousands, of feet, Tasman Bay 

 was not merely a valley, but an elevated one ; and the moun- 

 tains by which we are surrounded, having a much greater 

 altitude, were covered with perpetual snow, and glaciers filled 

 our now smiling valleys. This fact is borne out by the exten- 

 sive glacial deposits found in the Nelson District. The 

 Moutere Hills, and part of the Port Hills, are of glacial origin. 



