370 Transactions. —G eology. 
When we reach the interior of the North Island, we find immense areas — 
covered by pumice. This has been finally arranged in such a way that it 
could only have been done by the action of water. We find it spread out 
in large plains or in gentle undulations, and we also find it terraced. How 
are we to account for this? The pumice as thrown out by the volcanoes 
would not arrange itself in this manner. The action of rivers, of running 
water, is inadmissible. The pumice would be deposited only upon the old 
banks of rivers. A depression of the land to admit the action of the sea is 
inadmissible. We do not find in the pumice deposits any marine fossils, 
and if we were to admit the ocean without due precautions, all the pumice 
would be carried out to sea. 
Circumstances force us to adopt the hypothesis of extensive lakes in the 
interior. When we have once got hold of the idea, I do not think the proof 
is very difficult. 
For instance, the Upper Waikato forms a basin, the Lower Waikato 
forms another basin, each surrounded by hills on all sides. Before the 
river had cut a channel through the hills which separated the Upper from 
the Lower Waikato, the Upper Waikato must have formed a lake. Before 
the river had opened a channel through the ranges which separate it from 
the sea, the Lower Waikato must have formed another lake. Any one who 
knows the district must see this at a glance. 
As the river gradually cut its way through the hills, water-logged* 
pumice would be left behind in terraces, but previously to this the pumice, 
by the distributing action of the waters of the lakes, would be spread over 
the whole area. There is, I think, no other way of accounting for the dis- 
tribution of the pumice. 
In the country skirting Ruapehu to the south, the outcrops of the marme 
tertiaries rise as a fringe. Before this fringe was broken through by the 
rivers, lakes must have existed at the base of Ruapehu. On the Ruamata 
Plains on the western side of that mountain, or perhaps, rather of Ton- 
gariro, I observed large deposits of pumice, evidently arranged by water, 
and necessarily by the waters of a lake, 
I haye not seen the large deposits of pumice to the north and east of 
Lake Taupo in the direction of the Thames and hot lakes, and shall, 
therefore, say nothing about them, except that I have no doubt that their 
distribution has been caused by water, and of necessity by the waters of a 
lake or lakes. To go beyond the pumice country, a great part of the 
Forty-Mile Bush, in the Provinces of Wellington and Hawkes Bay, must _ 
*Tam in doubt whether pumice will become water-logged. If not, we can easily 
account for its position by its being gradually left 
through the ranges, slowly lowered the waters of the lake, 
, ag the river in cutting its way 
