THE ORIGIN OF THE FAUNA AND FLORA OF NEW ZEALAND, 257 
hemisphere a diluvial epoch ; but we shall see directly that there 
is no evidence at all of its having produced a glacial epoch. 
Although there is no reason to suppose that any very im- 
portant geographical changes occurred in the southern hemis- 
phere during the pleistocene period, it is almost certain that dur- 
ing earlier tertiary times there was a greater extension of the 
Antarctic continent between S. America, S. Africa, and New 
Zealand. What effect this had on climate is doubtful. Accord- 
ing 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 glacialepoch ; 
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 palzeontological evidence of any 
ereat change of climate in the southern Hemisphere during the 
pliocene and pleistocene periods. In S. America, according to 
Mr. Darwin, the raised beaches contain the same species of mol- 
lusca as at present live in the neighbourhood. The same is the 
case in New Zealand, both with the pleistocene and pliocene 
deposits ; and no one has ever proved that any difference is to 
be found in S. Africa. So the evidence 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 hemisphere. 
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 nor boulder clays, and no stratified moraines. 
There are no true erratics—z.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 
moraine shingle or sandspits are found Jdetween some of the 
moraines on the west coast of the South Island, as a proof that 
those glaciers entered the ¢-2:}+ but this might well be due to the 
subsidence after the glacier epe h, of which, as I shall presently 
- point out, we have many independent proofs. If these glaciers had 
_ reached the sea their moraines would shew traces of having been 
deposited in water quite as much as the shingle spits between the 
moraines. 
In the third place, the cold that would be necessary to bring 
back our glaciers to their former dimensions would be sufficient 
*Island Life, p, 193. 
t Geol, of Canterbury and Westland, p. 378, 
