Along the slopes of the Richardson Mountains, west of the Mackenzie Delta in the Northwest Territories of Canada, the stratigraphies of two lakes with large retrogressive thaw slumps within their catchments are examined using paleolimnological techniques. The lacustrine geomorphological impacts of current thaw activity are examined, as well as the past occurrence of large-scale thermokarst disturbances. Sediment stratigraphies from the larger lake suggest repeated erosion through time. The sediment stratigraphy from the smaller lake records ~55 cm of deposition due to thaw slump activity in the past 20 – 40 years. Aside from the recent thaw slump activity recorded in the smaller lake basin, neither system provided discernable evidence of long-term, ancient slump activity. The difference in the magnitude of impacts of the two systems is primarily attributed to catchment area to lake area and disturbance area to lake area ratios.