306 Transactions.—Geology. . 
miocene age, but, as yet, there are no data from which this can be satisfactorily 
ascertained. They certainly overlie sandstones and shales of miocene age. 
When the great moraine in question reached the flank of these hills it was 
deflected to the east and west, stretching in the former direction for three or 
four miles, and even crossing the watershed into the Wairau Valley, and in 
the latter for several miles down the valley of the Buller. This moraine is of 
stupendous dimensions, and was evidently deposited by a glacier which 
occupied the site of the lake and of the valley above it, and the surface of which, 
judging from the height of the lateral moraines, must have stood at least 1,000 
feet above the present level of the water. The lake itself is several hundred 
feet in depth in its deepest part, the slope increasing from each extremity, 
but most rapidly from the lower end. It is difficult to account for the great 
depth of this lake as compared with the general slope of the valley of the 
Buller, unless we assume that before the elevation of the land its bed was 
filled with the same materials as compose the hills in front of it, and that 
these were gradually ploughed out or otherwise removed by the glacier. There 
can be no doubt, indeed, that a glacier will easily remove loose materials from 
a pre-existing depression to a depth considerably below the level of their 
surface on the lower side of the terminal moraine, or, in other words, will 
scoop out such materials to a depth greatly exceeding the general slope of the 
valley, but they cannot be removed- unless forced more or less up a slope, 
and brought within the influence of the stream which issues from the foot of 
the glacier. 
If, therefore, the site of Lake Arthur and of the valley above it, as well as 
of that part of the Buller which is now occupied by the moraine, was filled 
before the formation of the glacier with the same gravels and sands as compose 
the hills on its northern side, or with any other loose materials, I see no 
difficulty in believing that the portion of those materials which lay in the lake 
depression below the level of the general slope of the valley has been removed 
by the glacier, leaving the lake basin to be refilled by the alluvium which has, 
since the disappearance of the ice, been and is still being carried into it by the 
main river and by the innumerable streams which furrow the ranges on 
each side of it. 
I have already alluded to certain facts in relation to the action of the 
glacier which formerly occupied the valley of the Dillon, but there are some 
circumstances of a special character in connection with it, which render it 
necessary that I should give more details of the physical features of the 
district, in order that my subsequent remarks may be understood. 
The Dillon has its principal sources in the Pyramid Mountain, a huge 
peak to the north of Mount Franklin, and for the first ten or twelve miles of 
its course is fed by innumerable small torrents which drain the rugged slopes 
