EXPLORING PERMAFROST MELTING WITH GOOGLE EARTH:
RETROGRESSIVE PERMAFROST IN THE YUKON AND NORTHWEST TERRITORIES
An excellent selection of sites in the Yukon showing significant slides and regression of permafrost in mineral soils was made available on Google Earth by "kingpointnorth" (Google Earth BBS link). Some of the sites like the near the Bonnet Plume River have some excellent high resolution digital camera image overlays.
In the context of climate warming, it is interesting to look at some of these sites over a period of 50 years or more. Aerial photography has been taken in the North since the mid 1920's. From the 1950's on aerial photography becomes a more dependable source of information for comparison. (See the National Air Photo Library on-line site).
I have taken a few if the sites and analyzed the information below from a time series perspective.
This site is within the Peel River Plateau Ecoregion and the Taiga Plain Ecozone. The landscape is almost entirely shaped as result of the Laurentide glaciation, and post glacial fluvial and other geomorphological processes. Continuous permafrost is present with depth to base of ice-bearing permafrost close to 300m (Geological Survey of Canada, unpublished data). Retrogressive thaw flow slides are common where ground ice has been exposed in glaciolacustrine deposits by forest fires, debris flows and regressive erosion. (Ecoregions of the Yukon: Peel River Plateau).