x877J 
Southern Hemisphere. 
34i 
that Captain Hutton’s ingenious argument is founded. He 
has given a list of a great number of mollusks found in these 
beds that do not now live so far south, whilst only a few 
occur that do not now live so far north.* This, he thinks, 
proves that there was no reduction in the general tem- 
perature in times immediately preceding the glaciation of the 
country. We do not know, however, the age of these pre- 
glacial deposits, and they may be as far back in time as 
our coralline crag, and the value of the evidence has been 
much lessened by some faCts described by Mr. C. W. Purnell. 
He states that at Wanganui there are three distinct fossil- 
iferous strata, separated by thick beds of volcanic mud, and 
that the shells of these different horizons are mixed together 
in Captain Hutton’s lists.! If this is so, it may yet appear, 
when the fauna of each zone is more critically studied, that 
the same evidence of a gradual refrigeration of the climate 
in the Pliocene epoch exists in New Zealand as in Europe. 
Captain Hutton further argues that as many of the shells 
that extend back to the Miocene epoch, and still exist on 
the coast of New Zealand, are littoral species, and are not 
found elsewhere, we should have to suppose, if the extension 
of the glaciers was due to the change in the climate, that 
during the cold period they crossed the deep sea to Australia 
or Polynesia, and that, on the return of a warmer cli- 
mate, they all came back again to New Zealand without 
leaving any behind on the coasts they had retired to during 
the Glacial period. He concludes, therefore, that since the 
Miocene period there can have been no reduction of tem- 
perature sufficient to account for the former extension of the 
glaciers, and that we must necessarily look to elevation of 
the land as the main cause. He admits, however, that it is 
possible that the two may have been combined, but con- 
siders that at present the evidence seems to be in favour of 
there never having been a Glacial epoch in New Zealand, 
and consequently none in the southern hemisphere.^ 
Now, if the theories I have advocated respecting the 
Glacial period are correct, the two conditions of the glacia- 
tion of the land, and at the same time its relatively greater 
elevation above the level of the ocean, must have existed 
together. For such an amount of ice as is necessary could 
not be piled up around and outside the ArCtic and Antarctic 
circles at the same time without abstracting so much water 
* Trans. New Zeal. Inst., vol. viii., p.383. Captain Hutton has also pub- 
lished an abstract of his views in the Geological Magazine, 1875, p. 580. 
f Trans. New Zeal. Inst., vol. vii., p. 453. 
£ Ibid., vol. viii., p. 387. 
