ABSTRACT: Dendrochronology and retrogressive thaw slumps on Midway Lake Plateau Fort McPherson.

CGRG Bibliography of Canadian Geomorphology
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Abstract

In absence of ocular witness and in absence of yearly satellite images or aerial photographs, dendrochronology is the best method to get the year of the catastrophic retrogressive thaw slumping in forested area on Midway Lake Plateau. In regions with distinct seasons, tree-ring analysis allows the datation of environmental hazards with yearly precision. Our hypothesis is that the age of the death of the sampled trees, determined by cross-dating, is the same as the thaw slump event which buried the sampled trees. This allows us to verify if slumps are related to heavy rains, or if some catastrophic slumps are the consequences of the 1944 and 1955 earthquakes in Richardson Mountains.The best locations to sample the trees in a slumped site are the channel banks developed in the slumped material which fill the valleys. There, fluvialerosion digs out tree trunks. Only broken tree trunks are sampled, because only hazards events in this region can have transported and broken them. Each sampled dead tree are recorded by GPS and described (size, position andsurrounding sediments). Pencil-sized increment cores and sanded trunk cross sections are measured in laboratory with a stereomicroscope system supported by a computer program.

Bibliography of Canadian Geomorphology