Fauna and Flora of New Zealand. 89 



rising to 800 in Canterbury and Otago ; and if this be true, 

 the Pleistocene submergence could hardly be due to displace- 

 ment of the sea caused by the attraction of an ice-cap on the 

 south pole, for the rise is too great and too rapid. 



That the former extension of our glaciers was not caused 

 by a cold period is, I believe, acknowledged by all New- 

 Zealand geologists, and also by the late Dr. von Hochstetter*. 

 Instead of a glacial epoch four other hypotheses have been 

 put forward to account for the phenomena : — (1) The first is 

 the elevation of the land, in combination with a more plateau- 

 like form of the mountains, which would thus collect more 

 snow f. (2) The second is elevation, in combination with 

 the subsidence below the sea of Central Australia J. (3) 

 The third is the plateau hypothesis alone, the land being at 

 the same level as now. It is supposed that these plateaux 

 have been reduced to sharp ridges by the erosion of the 

 glaciers, and thus the retreat of the glaciers is accounted 

 for §. (4) The fourth is elevation alone, the retreat of the 

 glaciers being caused by subsequent depression ||. 



These hypotheses resolve themselves into three, viz. subsi- 

 dence of Central Australia, broad plateaux, and elevation — 

 taken either singly or in combination. We will examine each 

 of them. 



The subsidence hypothesis is thus explained by its author : — 

 " One cause of the greater extent of the New-Zealand glaciers 



is that the elevation of the New-Zealand mountains 



was probably coincident with the submergence of the low land 

 in the interior of Australia, which is covered with a Post- 

 pliocene marine formation. The equatorial north-west winds 

 would thus impinge on the JNew-Zealand Alps without, as at 

 present, being deprived of a large amount of their aqueous 

 vapour by passing over the arid plains of Australia, and the 



* ' New Zealand ' (1807), p. 505. 



t Hector, "Geological Expedition to the West Coast of Otago/' 'Otago 

 Provincial Gazette,' 5th Nov. 18(33, and Trans. N. Z. Inst. vi. p. 374 

 (1878). 



\ Hector, in a letter to Sir J. Hooker, dated loth Jul}', 1864, in Lyell's 

 ' Principles of Geology,' 12th ed. vol. i. p. 248 ; and Trans. N. Z. Institute, 

 vi. p. 385 (1873). 



§ Haast, Q. J. G. S. xxi. p. 185 (1804), and ' Geology of Canterbury 

 and Westland/ pp. 872-4 (1870). In Lis 'Geology of Canterbury' 

 (p. 370) Dr. v. Haa*t says that I was the former chief exponent of the 

 theory that the extension of our glaciers occurred diu'iug a partial sub- 

 mergence of the land. I do not know to what Dr. v. Haast alludes. The 

 submergence that 1 have always advocated was in the Pleistocene, after 

 the glacier epoch was over. 



j| Dobson, Trans. N. Z. Inst. iv. p. .'J40, and vi. p. 2'J4 ; Travers, Trans. 

 N. Z. Inst. vi. p. 299. 



