Hi Kingpoint. Your picture of the Bonnet Plume River permafrsot slide is really excellent and provides a good indication of active slide areas as well as vegetation cover. The area was burned between 2000 and 2004 according to fire history records.

I looked again at some old photographs from the national Air Photo Library collection in Ottawa. Below are some examples. The coverage started in 1949, 1953, 1968, 1994. The slide started already before 1949. Much earlier than I exected. In fact the photos of 1949 showed a significant amount of thaw features which since have stabilized. A number continued to grow as this one. The average melting rate between 1949 and 2007 is about 7 meters per year. The last 14 years the rate appears to be on the average about 11 meters per year.

I will do some more work on this, but in the meantime here is the overview image. Your aerial photo provides an excellent reference for interpreation.

More information can be found at my website: http://www.geostrategis.com/g_permafrostslide-bonnet.htm