306 Tra7isacticms. — Geology/. 



miocene age, but, as yet, there are no data from whicli 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 sevei-al 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 de})th in its deepest part, the slope increasing from each extremity, 

 but most rapidly fi-om the lower end. It is difficult to accou'nt for the great 

 dejDth 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 np 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 flUed 

 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 thei^e are some 

 circumstances of a sjjecial 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 



