CGRG Bibliography of Canadian Geomorphology
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Author : Calmels, F.; and Froese, D.G.
Date : 2008.
Title : -Permafrost dynamics in the Klondike goldfields, central Yukon.
Publication : Joint Annual Meeting of the Canadian Geophysical Union and the Canadian Geomorphology Research Group. May 11-14, Banff, Alberta.
Issue :
Page(s) :
Abstract
The Klondike goldfields of central Yukon provides an exceptional opportunity to study permafrost dynamics in the subarctic of North America. The combination of a century of placer gold mining and the exceptional exposures of permafrost-related features provides the opportunity to investigate permafrost at timescales of decades to millennia. Here we present preliminary results of research aimed at understanding the controls on permafrost degradation at different temporal scales using multiple types and ages of disturbances; and secondly evaluate the regenerative capabilities of permafrost following cessation of disturbance. In this study we utilize disturbances ranging from the last few years to Gold Rush era disturbances in the early part of the 20th century. First, sites in the Klondike area, where permafrost has been thermally disturbed by the removal of peat and vegetation cover (following fire or mining activities), allow rates and processes governing permafrost degradation to be established. Geocryological profiles, and ground temperatures help to assess permafrost degradation rates and the relative influence of different factors on degradation. Borehole observations suggest that permafrost table depths in recently degraded sites can deepen by as much as 20 cm / yr following a perturbation such as fire. Secondly, we investigated much earlier disturbances in the area, related to Goldrush era activities (in this case the development of a telegraph system). The perturbation, now about a century old, underscores the importance of vegetation cover, and its re-establishment, in influencing permafrost degradation or recovery. Preliminary observations suggest that the permafrost table re-aggraded following significant deepening (ca. 2 m) to the recovery of a ca. 0.5 m active layer thickness. Advanced technologies for permafrost characterization such as CT-scanning of samples and ground penetrating radar will be used as well as thermal analysis from climate and ground temperatures. Sampling will characterize the frozen ground in sedimentological and cryological terms. In addition, isotopic analyses will be made to assess the timing (ie. presence of tritium) and environmental factors influencing the degradation and re-aggradation processes. Collectively, these observations will allow us to “read” the complete history of the permafrost degradation/re-aggradation.
Bibliography of Canadian Geomorphology