Plain Language Summary
Retrogressive thaw slumps (thaw slumps) are a form of landslide that occurs when thick layers of ice under the ground are exposed and thaw, creating muddy flows that can grow to cover thousands of m2 in just a few years. These processes are occurring more frequently in the western Canadian Arctic during the last two decades, becoming one of the primary causes of landscape change. This research examines how variation in the ice and overlying soil thickness of the thaw slump headwalls (a prominent, near vertical cliff at the back of a thaw slump), affects their rate of growth. We find that a persistent layer of ice, and a thin soil overburden, tends to promote headwall retreat rates much faster than otherwise. We also show how simple, cost-effective and quick measurements can be used to map the buried ice and show how it varies inland, and then use this information to improve predictions of how fast the headwall will retreat. This research suggests that detailed knowledge of how the internal ice and overburden layering varies is critical to understanding how thaw slumps evolve and to predict their development.