Permafrost Thaw 1966-2005 Trevor Range Site 1, Yukon.kmz

Permafrost Thaw 1966-2005 Trevor Range Site 1, Yukon.

1966 aerial photo from 30'000 ft
1966 Aerial Photo taken at 30'000 ft. July 20.
Source : (A19650 -67) National Air Photo Library, Ottawa
Interpretation: Jean Thie, Ecoinformatics International
More Information: www.geostrategis.com
This strereopair shows the start of permafrost melting in 1966 (red arrow). The thaw continued at a rate of about 20 meters per year. The most significant melting occurred in the last 14 years. The 2004 edge is clearly visible on the Google Earth (Digital Globe Image) which becomes visible when the airphoto is made transparent.

Retrogressive Thaw Trevor Range Site 1
SITE 1: Retrogressive Permafrost Thaw Slide, Trevor Range, Yukon Territories, Canada
Source of location: Kingpointnorth, Google Earth BBS
Interpretation: Jean Thie, Ecoinformatics International
More Information: www.geostrategis.com
Figure 1 below shows a comparison and interpretation of a series of aerial and satellite images. The left is an 1966 July Aerial photo (A19650-67) draped over a Google Earth. To the right is the Google Earth high resolution Digital Globe image (July 2004). The grey dotted lines show the permafrost melting/ erosion edge in 1966. The Yellow dotted line is derived from a NASA Landsat 1990 low resolution image interpretation (WorldWind) and the orange dotted line is represents the GE 2004 digital Globe image.
Figure 1 (larger version+)
The regression distance over the 38 year period is about close to 850 meters, while the active edge is close to 890 meters in length. Average regression rate would be in the order of 20 meters per year. Most of it, certainly volume wise, in the last 14 years. There ar no indications that this slide has been triggered by wildland fires as there is no evidence of fire history on the aerial and satellite images.
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permafrost is present with depth to base of ice-bearing permafrost close to 300 m (Geological Survey of Canada, unpublished data).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).
This melting and regression rate is comparable to other rates documented in the Yukon. For example Burn and Friele(1989 Arctic vol. 42 no.1, p31-40) measure regression rates of up to 16 meters per year in retrogressive thaw slumps near Mayo, Yukon Territory.