Fauna and Flora of New Zealand. 87 



Although there is no reason to suppose that any very im- 

 portant geographical changes occurred in the southern hemi- 

 sphere during the Pleistocene period, it is almost certain that 

 during earlier Tertiary times there was a greater extension of 

 the antarctic continent between South America, South Africa, 

 and New Zealand. What effect this had on climate is doubt- 

 ful. According to Mr. Wallace it produced a long persistent 

 more or less glaciated condition * ; while Dr. Martin Duncan 

 invokes the same antarctic continent as the cause of a warm 

 Miocene sea. 



Other hypotheses depending on cosmical causes, and there- 

 fore affecting the whole world — such as a change of obliquity 

 in the ecliptic or a decrease in the heat derived from the sun — 

 have been put forward to account for the European glacial 

 epoch ; but as these hypotheses have very few adherents, 

 they need not be discussed here, especially as I believe it to 

 be possible to bring forward sufficient evidence to prove that 

 our great glacier epoch was not due to a general reduction of 

 temperature in the southern hemisphere, and therefore was not 

 due to any cosmical cause affecting the whole earth. 



In the first place there is no palgeontological evidence of 

 any great change of climate in the southern hemisphere during 

 the Pliocene and Pleistocene periods. In South America, 

 according to Mr. Darwin, the raised beaches contain the same 

 species of Mollusca as at present live in the neighbourhood. 

 The same is the case in New Zealand both with the Pleisto- 

 cene and Pliocene deposits ; and no one has ever proved that 

 any difference is to be found in South Africa. So the evi- 

 dence of migration from polar regions towards the equator, 

 which forms such a cogent part of the proof of a European 

 glacial epoch, is altogether wanting in the southern hemi- 

 sphere. 



In the second place, our glaciers were always confined to 

 valleys, and there is no proof that they ever reached the sea. 

 There are no tills or boulder-clays and no stratified moraines. 

 There are no true erratics, i. e. blocks brought from some 

 other drainage-system, and no marine shells have ever been 

 found in any of the glacier deposits, even in those which are 

 now at the sea-level. Dr. von Haast certainly adduces the 

 fact that marine shingle or sandspits are found between some 

 of the moraines on the west coast of the South Island as a 

 proof that those glaciers entered the sea f ; but this might 

 well be due to the subsidence after the glacier epoch, of which, 

 as I shall presently point out, we have many independent 



* 'Island Life,' p. 193. 



t Geol. of Canterbury and VVestland, p. 878. 



