Physiography, Geology.] SUBANTARCTIC ISLANDS OP NEW ZEALAND. 717 



will find them. Glaciers certainly filled the valleys, but it is extremely unlikely that 

 they ever approached even in a modified from to the character of a continuous ice 

 covering, and, further, the biological evidence is totally opposed to its occurrence. 



The establishment of the fact that these islands were glaciated within recent 

 times is of the utmost importance in its bearing on the origin and present 

 character of their fauna and flora, and especially on their flora. Biological considera- 

 tions are as weighty as geological ones when discussing the cause of the glaciation. 

 This glaciation can be explained most easily by supposing that the land was much 

 higher — certainly several thousand feet higher — than it is now. If we postulate a 

 general refrigeration, from whatever cause it might be — e.g., variation in the heat 

 of the sun, shifting of the earth's axis, &c. — we are at once faced with the fact that 

 the present subtropical element in the flora would have been wiped out unless it 

 re-established itself subsequently to the glaciation by migration from warmer lands. 

 This would imply a post-glacial elevation in order to make a land connection. In 

 order to explain the appearance of glaciers at sea-level in the locality without eleva- 

 tion of the land, the climate must have been arctic in severity, and this would have 

 been fatal to the rata and tree-ferns which flourish now in sheltered spots on the 

 island. 



The case of the Franz Josef Glacier, on the west of the Southern Alps, which 

 is so frequently instanced as an illustration of the association of a subtropical vege- 

 tation with glaciers, hardly applies in this connection. The Franz Josef takes 

 its origin in vast snowfields, which are concentrated into a somewhat narrow valley 

 of very steep grade, so that the glacier moves rapidly, and reaches a low level before 

 it melts. The circumstances are quite different in the Auckland Islands. At the 

 present level of the land it would seem impossible for glaciation to occur without 

 destroying the subtropical element in the vegetation, seeing that very few indeed 

 of our New Zealand alpine plants can stand the rigour of the climate of even 

 Kew or Berlin. We are driven, therefore, to consider elevation of the land as an 

 important factor, but not necessarily a predominating factor, in the extension of 

 the glaciation. If it were the sole cause of the glaciation, the land must have 

 reached at least 7,000 ft. in height. If we consider there are no present-day glaciers 

 on Mount Anglem, in Stewart Island* (height 3,200 ft.), though they existed there 

 formerly, and large glaciers are rare in the sounds country of Otago, and that it 

 is only when the mountains reach a height of more than 8,000 ft. that glaciers of 

 considerable size occur in the Southern Alps, it would seem reasonable that the 

 Auckland Islands were at least 7,000 ft. high : they may have been much higher. 

 This would allow the eastern valleys to be filled with snow, and would probably 

 accoimt for all their special features ; and, further, as the land sank it would fully 

 account for those features due to a waning glaciation. This theory would apparently 

 account for the facts in the present case ; but when it is considered that glaciation 

 was fairly severe over a large part of the Southern Hemisphere in Pleistocene 

 times, and elevation cannot be cited in every case as an explanation of it, this 

 apparently simple solution of the difficulty in the case of the Auckland Islands must 

 be accepted with considerable reserve. But there is proof of a slight elevation, 

 whatever the cause of the glaciation. 



* " Botanical Survey of Stewart Island," by Dr. L. Cockayne, 1909, p. 6. 



