Sir,

I recently visited the Cameron Glacier, a small one in the Arrowsmith Range, Canterbury. It lies about ten miles to the south-east of the glaciers in the upper Rakaia Valley, whose marked retreat I described in a recent issue of the Journal (Vol. 1, No. 9, p. 504–7). There is no evidence of appreciable recession of the Cameron since Speight photographed it forty years ago, but it has wasted down by as much as 200 ft. (61 m.), recalling Speight’s own observations of the very much larger and better-known Tasman Glacier. In his contribution to No. 8 issue of the Journal (p. 422–29), Suggate seems to have established the general character of the minor climatic fluctuations that influence the behaviour of the Franz Josef and Fox Glaciers in Westland, so that one wonders why glaciers descending east of the Main Divide respond differently. I suspect that two factors are important. First, the positions of the terminal faces of the steeper, more rapidly flowing Westland glaciers may fluctuate in response to nett alimentation changes more readily than those of the Canterbury glaciers. Second, cycles. of westerly weather bring heavy precipitation on and west of the Divide, but are often accompanied by conditions favouring increased ablation at lower levels on the eastern glaciers. Glaciers such as the Cameron are perhaps at present in a state of temporary equilibrium where alimentation increases at high altitudes are balanced by increased ablation losses at lower levels. However, the marked thinning of the trunk portion of the glacier suggests that stagnation and decay may be imminent. I have written a short account of the Cameron and its bearing on these questions, which is to appear in the New Zealand Journal of Science and Technology.

22 March 1951