340 
Glacial Period in the 
ijuiy, 
having then been higher. Dr. HeCtor, who first suggested 
this explanation, candidly admits that the shore deposits do 
not support it, and considers that there must have been 
unequal movements of elevation, and that the former 
greater weight of the mountains was due to their greater 
bulk, which has since been reduced by denudation. 
Dr. HeCtor, so far as I can make out from his writings, 
only seems to offer this as an alternative to accepting the 
occurrence of a general Glacial epoch, and we must turn to 
the works of Captain Hutton for the reasons that have weighed 
with the New Zealand geologists in rejecting the theory of 
a Glacial period, which, since Agassiz first propounded it for 
the northern hemisphere, has been adopted by nearly all our 
leading geologists. In the first place Captain Hutton thinks 
that the date of the last great glacier period of New Zealand, 
must be placed much further back than that of the northern 
hemisphere, because, since it occurred, some of the old lake 
basins have been filled up with deposits brought down by 
the streams ; the surfaces of the rocks that were formerly 
covered with ice have been weathered to a depth of ten or 
twelve feet ; old river courses have been filled with gravels, 
and the streams have cut new channels to great depths, so 
that in many places the drainage system of the country has 
been altered.* But in reality these faCts should rather have 
been advanced as evidence of the analogy of the glacial 
phenomena of the two hemispheres instead of as a distinction 
between them. We have but to appeal to the erosion of the 
deep gorge of the Niagara, for at least a distance of three 
miles since the glaciation of Canada, to the reversal of the 
drainage of the great lakes from the Mississippi into the St. 
Lawrence, to the buried old river channels of the north of 
England and of Scotland, and to the numerous filled-up lake 
basins of Europe and America, to show that it is the resem- 
blances and not the differences that strike us with greatest force. 
Captain Hutton has not, however, restricted his argument 
to the physical side of the question, but has sought to 
strengthen it by appealing to the evidence of the organic 
remains. It is admitted that the Glacial deposits contain 
no marine organism, but, as we have already seen, they over- 
lie beds of gravel and sand, with sea shells of late Pliocene 
age, as shown in the Oamaru section. These late Pliocene 
deposits are largely developed at Wanganui in Cook’s Strait, 
and it is from a study of the present and past range of the 
species of the marine mollusks in these and similar beds, 
* Geology and Gold Fields of Otago, p. 94. 
