Abstract The term quick clay has been used to denote the behaviour of highly sensitive Quaternary marine clays that, due to post depositional processes, have the tendency to change from a relatively stiff condition to a liquid mass when disturbed. On failure these marine clays can rapidly mobilise into high velocity flow slides and spreads often completely liquefying in the process. For a clay to be defined as potentially behaving as a quick clay in terms of its geotechnical parameters it must have a sensitivity (the ratio of undisturbed to remoulded shear strength) of greater than 30 together with a remoulded shear strength of less than 0.5 kPa. The presence of quick clays in the UK is unclear, but the Quaternary history of the British islands suggests that the precursor conditions for their formation could be present and should be considered when undertaking construction in the coastal zone.

Abstract A number of landslide types in Canada are concentrated in physiographic regions and are associated with certain kinds of soil and rock materials, geologic structures, and topographic settings. They include (1) mountain slopes in the Cordilleran region of western Canada, chiefly steeply dipping bedded and foliated rocks; (2) valley sides in Upper Cretaceous argillaceous bedrock, mostly bentonitic marine clay shale, silty shale, and mudstone; (3) river banks and terrace bluffs in the St. Lawrence Lowland region and lower coastal regions of eastern Canada, where postglacial marine submergence and postglacial uplift formed sensitive fine-grained marine deposits; and (4) valley walls, escarpments, and deep thaw basins in the Lower Mackenzie Valley region and adjoining plains of northwestern Canada, where ice-rich permafrost occurs in fine-grained soil and weathered shale materials. Rock avalanches, massive retrogressive slope failures in argillaceous bedrock, and major retrogressive flow slides and earthflows in quick clays are discussed under six headings: (1) morphologic features, (2) stratigraphy and lithology, (3) geologic conditions affecting failure, (4) character and rate of movement, (5) engineering and environmental implications, and (6) case histories. A few other landslide types are discussed but are not presented under these headings.