326 Trai,mcUoui<. 



furrows. This is especially well seen on the south shore of Lake Heron, 

 where the full force of the northerly wind is felt and the beach is shelving 

 and low. 



5. Present Glaciers. 



The existing glaciers of the area are divided into two groups — (1) those 

 coming from Mount Arrowsmith and its immediate neighbouring heights ; 

 (2) those which belong to the main Rakaia Valley. The principal glaciers 

 of the first group are those at the head of the Cameron and Ashburton 

 Rivers. Several other small ones occur, notably those at the head of the 

 Lawrence, on the western flanks of Mount Arrowsmith. 



(rt.) Cameron and Ashburton Glaciers. 



The former glacier occupies about two miles of the upper part of the 

 Cameron Valley. It is a small glacier of the first order, and is fed from 

 tributaries coming from the south-eastern slopes of Mount Arrowsmith and 

 its extension to the north. The lower part is covered with debris, and 

 shows undoubted signs of recent retreat. At the present time it is almost 

 impossible to tell the actual position of the terminal face, owing to its 

 extreme thinness and the mantle of debris which passes insensibly from 

 actual moraine to the apron of detritus before the glacier. This retreat is 

 also evidenced by the presence of old lateral moraines lying parallel to the 

 valley-sides far above the present level of the ice, and extending down the 

 valley for some distance beyond the present termination. 'There is also 

 there a well-marked terminal moraine about half a mile from the present 

 face. At various positions, besides, down the valley are old terminals pass- 

 ing into laterals, and partially blocking the stream in several places, which 

 marked in former times undoubted halting-stages in the retreat of the ice. 



A special feature of the valley is the wide basin which forms its head^ 

 a basin evidently expanded by the saj)ping-back of the containing-walls 

 in all directions by the ice which partially filled it. This case certainly 

 suggests that corrie glaciers and glaciers which are closely related to them 

 in size have under some conditions the power of widening their upper 

 reaches at a faster rate than the streams which issue from them can widen 

 that part of the valley where they flow. There is no suggestion furnished 

 by this locality that such glaciers act as protecting agents. 



The Ashburton Glacier lies to the west of the Cameron in a parallel 

 valley, and exhibits features very similar to those of its neighbour. It is 

 not as large as the Cameron, and hardly reaches the floor of the valley before 

 it melts ; but it is very beautiful, and shows striking crevasses and ice- 

 pinnacles, and a fine ice-fall at its head, depending from the slopes of 

 Arrowsmith. All down the valley in its front are the remnants of old 

 lateral and terminal moraines in positions where they have escaped destruc- 

 tion by the river, and marking halting-stages in the general retreat of the 

 ice. Immediately in front of the present face lies an immense accumu- 

 lation of angular debris belonging to a former period, and there is evidence 

 that the glacier has been dwindling within very recent times, though, 

 judging from the present form of the ice-face and also from the fact that 

 in one or two places it is crowding on to the old moraine, a temporary 

 advance is now taking place. 



The valley through which the Ashburton River flows is at first broad 

 and flat-bottomed, but about twelve miles from its commencement it 

 stiddenly contracts, and the vWev passes through a deep, narrow gorge, of 



