302 Transactions. — Geology. 
land, which extended to an altitude exceeding that of the present mountain 
chain by at least 4,000 to 5,000 feet, and that they attained their maximum 
extension coincidently with the maximum of elevation. They also lend 
strength to the assumption (founded on other independent grounds) that 
during the period of maximum elevation the land of which the present New 
Zealand islands proper are the chief remnant had a quasi-continental extension, 
chiefly to the eastward, and embraced, a£ least, the chain of islands above 
referred to. And they further justify us in attributing the disappearance of 
the glaciers in question to a depression of the land continued up to a 
comparatively recent period, a circumstance which, I think, is chiefly indicated 
by the following facts, namely :—That the larger number of the valley lakes 
which still exist above the terminal moraines of glaciers of the first order in 
those portions of the range in question which intervene between Mount 
Cook and the Spencer Mountains (as for example, Lake Sumner on the line of 
the Hurunui River) have been only partially filled up with alluvium, 
although the rivers which feed them are all shingle-bearing torrents; whilst, 
on the other hand, the lake which succeeded the great glacier of the Dillon 
has actually been filled with alluvium within the period which its outlet has 
occupied in cutting down the moraine dam to a depth of 35 feet only, fora 
distance, having regard to the general fall of the valley, of little more than 
half a mile. 
With regard to the probable time at which the upheaval referred to took 
place I can offer but few observations, So far as I can understand from the 
reports of the Geological Survey, we have no evidence of any upper marine 
pliocene beds in the Middle Island, whilst the upper portions of the miocene 
series are found at elevations varying from 1,200 to 1,800 feet above sea level. 
I therefore assume that the elevation in question commenced at the close of 
the miocene period, and that the more recent pliocene deposits within the 
Novo-Zealandian Proviuce would only have been found on the outside 
boundaries of the quasi-continental area which existed when the elevation 
referred to attained its maximum, and were submerged during the subsequent 
subsidence of the land. Тһе total elevation most probably approached 
9,000 to 6,000 feet, the subsequent depression exceeding that by at least 
from 1,200 to 1,500 feet. At what time the depression ceased it is difficult to 
Say, but it probably continued in pleistocene times, when a re-elevation of the 
land again took place. 
