A major landslide of the flow variety took place in the fall of 1924 in the Lake St. John region of the Province of Quebec, Canada. The slide involved 2.5 million cubic yards (2.0 × 106 m3) of clay and resulted in loss of life and considerable damage to property. A review of the circumstances preceding failure, the geotechnical properties of the clay and the mechanism of the slide movements is presented in the paper.