1876.] Lake Wakatipu, New Zealand. 389 
lar pebbles and containing fossil shells (Crassatella ampla) 
These deposits speak of other although minor changes during the 
time that the waters of the ocean occupied the valley. 
(3.) In the third stage the land is again upheaved to the dig- 
nity of a mountain chain, whose lofty summits become covered 
with vast fields of snow and ice, which, seeking an equilibrium, 
again flow as a glacier down the valley of Lake Wakatipu. 
This second extension of the ice-stream down the old valley re- 
sulted in the removal not only of most of the limestone that had 
been deposited, but also of fourteen hundred feet of the crystal- 
line rocks beneath. The limestone on the shore of the lake is 
thus shown to be an inter-glacial deposit, not by being inter- 
stratified with beds of till, but by the existence above and be- 
low it of distinct glacier-worn valleys. ; 
These great glaciers of New Zealand, together with the occur- 
rence of erratics and moraines in Natal, South Africa, as de- 
scribed by G. W. Snow,! indicate a time of extreme cold in the 
southern hemisphere, corresponding to the glacial epoch that left 
its records — in the form of striated rocks, bowlders, and moraines 
— over the northern hemisphere as far south as the fortieth par- 
allel. The limestone of Lake Wakatipu is similar in position to 
the inter-glacial lignite beds of Switzerland, as described by 
Professor Heer, and to the inter-glacial forest-beds of Scctland 
and America. Geologists will notice, however, the greater age 
of the limestone of Lake Wakatipu, which, as indicated by its fos- 
sils, is Upper Eocene, but whether synchronal with the Eocene of 
trope has yet to be determined. 
The great extension of these ancient glaciers may also be 
Owing, in part at least, to a greater elevation of the land. 
Either condition returning to those rich and promising islands, 
they would again become wrapped in ice and snow, which would 
swell the ice-streams from Mt. Earnslaw to their ancient dimen- 
“ons and re-create those giant glaciers. 
The second glacier, like the first, had its period of great ex- 
tension and then slowly passed away. As its terminus retreated 
Up the valley it left behind it the material it had gathered from 
the overhanging cliffs along its course, or had torn from the sides 
of the valley, together with the finer products ground by the 
ttom of the glacier from the rocks over which it passed. This 
material now forms the filling of the valley below the lake, and 
n worked over, perhaps many times, by streams of water 
z Quarterly Journal of the Geological Society, xxvii. 540. 
