The Editor,
Journal of Glaciology
Sir,
The distribution of surging glaciers in western North America led Reference Meier and PostMeier and Post (1969) and Reference Meier and PostPost (1969) to suggest that both temperate and non-temperate glaciers can surge. Field measurements by Reference Classen and ClarkeClassen and Clarke (1971) have indicated that Rusty Glacier falls into the second category, but field measurements have not yet identified a temperate surging glacier. If temperate glaciers can surge, the temperature instability considered by Reference RobinRobin ([1956]) is unlikely to be a necessary condition for surge behavior.
Variegated Glacier, located 55 km from Yakutat, Alaska, and reaching almost to tidewater near the junction of Russell Fiord and Disenchantment Bay, is an excellent candidate for a temperate surging glacier (Reference Meier and PostPost, 1969). Its surge history is long and well known (Reference Tarr and MartinTarr and Martin, 1914; Reference Meier and PostPost, 1969), the last surge being in 1965. My wife Anne and I carried out a reconnaissance of this glacier from 4 to 7 September 1971. We went to investigate the suitability of the glacier for more extensive field study, and to obtain some first-hand information about its thermal regime.
We carried snow-probing and thermistor equipment 25 km from tidewater to a point near the head of the accumulation area at about 1 550 m elevation. Prudence in the face of a crevasse field and 0.2 m of new snow prevented us from reaching the very highest point 300 m higher. The snow line was between 800 and 1 000 m. We made several measurements of firn temperature with the results shown in Table I.
Table I. Temperature Measurements in Variegated Glacier
The random error (standard deviation) is about 0.004 deg; the calibration error, about 0.006 deg. From the inspection of the wall of a crevasse, we concluded that at the highest two points the thermistor was about 1 m deeper than the 1970 ablation surface, but our identification of the 1970 horizon was not unambiguous, and the thermistor could have been about 1 m above it. At any rate, it appeared that previous winter’s firn had been warmed to 0° C or very nearly so by early September.
This result suggests that there is nothing peculiar about the thermal regime of the glacier that might explain its surge behavior, although it should be noted that the result does not guarantee that the glacier is temperate everywhere (Reference MillerMiller, [1956]; Reference SchyttSchytt, 1969, for example). The situation is consistent with what Reference Meier and PostMeier and Post (1969) expected. Our field measurements lend some support to the idea that temperature instability is not a necessary condition for surge behavior.
