Nicolet is situated at the meeting of the Saint-Lawrence and Nicolet rivers, on sandy, unstable soil, making the area prone to landslides. **The main reason for the occurrence of the slide in Nicolet, Quebec is the type of soil in the area of which the slide occurred. Beneath the 8-foot thick stratified fine sand layer, was a thick stratified gray clay that extended to the depth of 35 feet and below that, was a darker clay with black mottling with a thickness of 100 feet. The clay is marine/Leda clay that is "extra sensitive" or "quick". The natural water content of the clay was above the liquid limit in some areas and above the plastic limit in others. Due to the salt concentration within marine clays, which would have crystallized as the marine water receded historically, the salt would be removed by rainfall and meltwater after winter. Glacio-marine clays and silts are common in this area due to the prior existence of the Champlain Sea, which used to occupy the St. Lawrence and Ottawa valleys post-glaciation.