Quick Clay Landslides, Landscape Evolution, and Climate Change: A Perspective from British Columbia

Abstract

I examine prehistoric and historic quick clay landslide scars in two valleys in northwestern British Columbia, and test the evidence against Bjerrum’s and Levebvre’s landscape evolution models. Streams in the Terrace-Kitimat valley are still incising deep glaciomarine sediments and appear to be in the early and intermediate stages of valley formation, thus large landslides are still occurring and more are expected. In contrast, streams in the Nass Valley are incised into bedrock, in the late stages of valley formation. Early evidence suggests most of the landslides are old, and more large landslides are not expected to be triggered by bank erosion. Rapid incision in the Nass valley may have overwhelmed climatic influences, however in the Terrace-Kitimat valley identified wetter climate regimes seem to correspond to higher earth flow activity. Here, a future warmer and wetter climate, as predicted by most global circulation models, will likely lead to increased landsliding.