Formes, figures et faciès sédimentaires glaciels des estrans vaseux des régions froides
Abstract Frost and drift ice are two important processes creating distinctive features in tidal flats of cold regions. Original sedimentary forms, figures and structures, and a particular facies, characterized by two opposite grain sizes (fine and coarse together), result from ice action in muddy tidal flats. Grooves or furrows, polished and striated surfaces, tracks and trails, various drag, roll and skip marks, circular depressions, chaotic microreliefs, pushed ridges, polygonal nets, monroes, lenticular bedding and deformations are common to intertidal zones along the St. Lawrence, and the James-Hudson Bay area, Canada. They also occur elsewhere in most tidal flats and on continental shelves dominated by ice. A better knowledge of drift ice features in modern tidal flats is needed. It is a prerequisite to the discovery of similar features in consolidated rocks. The finding of such indicators should improve greatly any interpretation of the paleoenvironmental conditions of deposition.