872 Transactions.— Geology. 
propose to consider the much vexed question of the formation of the Can- 
terbury Plains. I think the subject requires more discussion. 
The point to decide is, by what agency the gravels which cover the 
plains have been spread evenly round the contours of the skirting moun- 
tains ? 
There is little or no difficulty in accounting for the gravels. The rivers 
traverse ranges of mountains of which the rocks are peculiarly favourable 
for the formation of gravel, and, given sufficient time, possibly the agencies 
at present in operation would be sufficient for the production of all the 
deposit, without calling in the help of more ice. But the distribution of 
the gravel is the difficulty. Captain Hutton would submerge the whole 
area, and use the waters of the ocean as the distributing power. Ifa single 
marine fossil could be found in the gravels of the plains, this theory might 
be tenable, but the absence of such evidence in any part of the large area 
under discussion must, I thmk, be held to be absolutely fatal to the argu- 
ment. 
That the gravels have been distributed by water there can be no doubt, 
but rivers will not carry gravel up hill, or create a level beach-mark of 
gravel round the contours of the bounding hills. Having therefore. 
excluded the action of the sea and of rivers nothing would appear to remain 
to perform the work but the waters of a lake. 
To form the Canterbury Plains into a lake it is necessary to suppose & 
barrier of high land to the eastward. This is a serious mechanical 
operation, but not more difficult than it would be to submerge the plains 
beneath the sea. Let us see what arguments we can find in favour of the 
proposition. 
It is considered by many to be an axiom, that where volcanic eruptions 
have broken out the district is an area of subsidence, and in this part of the 
world we have strong evidence of the correctness of this view. 
We have the numerous volcanic islands of the Pacific with their 
fringing coral reefs, and we have every reason to suppose that the volcanic 
districts of New Zealand shew a subsidence from a former much higher 
level. Thus it is probable that when the eruptions of Mount Egmont first 
commenced the islands were, or had been shortly before, united, and that 
a gradual subsidence had been going on previous to the outbursts of this 
and other voleanoes to the northward. Apply this reasoning to the east 
coast of the South Island. We there find a line of volcanic eruptions, 
extending from Banks Peninsula to Dunedin, and shewing at Timaru, 
Moeraki, Waikouaiti, besides the before-named places. 
If this line shews an area of subsidence at or about the time of eruption 
it pre-supposes a former greater height of land in that direction, and thus 
