CGRG Bibliography of Canadian Geomorphology
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Author : Blumstengl, W.K.; and Harris, S.A.
Date : 1988
Title : Observations on an active lobate rock glacier, Sims River Valley, St. Elias Range, Canada
Publication : Permafrost: Fifth International Conference, Proceedings, August 2-5, 1988, Trondheim, Norway. Trandheim: Tapir
Issue : 1:
Page(s) : 689-694
Abstract
A forested, active lobate rock glacier 1.7 km long occurs on the east side of the Slims River Valley, 7.3 km south of Kluane Lake, Ukon Territory. It is developed in a diamicton with a loess cover over the lower one-third of its surface. The lower two-thirds is forested and the trees at the front move with the ground at up to 20 cm/a. Split trunks of trees, open crevasses and pressure ridges are common on the rock glacier, while tilted trees occur on the push-lobe developed in the silts in front of it. The rate of movement is consistent with creep of ice. Springs around the front show no diurnal fluctions, but discharge increases with increasing mean air temperature. 18O composition of the spring water and interstial ice within the rock glacier approximates the average of the present-day snow and rain. Tritium distribution in the interstitial ice indicates a decrease of 15-20 cm in the thinckness of the active layer on the rock glacier since 1953. Available measurements of moisture distribution into and within the permafrost suggest present-day moisture movement and accumulation of ice under the influence of near-surface temperture gradients. The interstitial ice is probably modern, and when the ice content reaches a critical value, movement commences.
Bibliography of Canadian Geomorphology