Pleistocene gravels of the Red River valley
Organ, David William
This thesis is based on field and laboratory studies of several Pleistocene gravel deposits in southeastern Manitoba. The deposit near Birds Hill receives special attention. North American topography has been greatly influenced by the widespread glaciation of the Pleistocene epoch. Ice-sheets of this epoch extended over the northern part of North America in four successive advances, named in order the Nebraskan, Kansan, Illinoian and Wisconsin glacial ages. With each recession of the ice-sheets a mantle of glacial till remained, to be overridden and modified by the next age of glaciation. The drift deposited by the Wisconsin ice-sheet remains today virtually unaltered over large areas of Canada and northern United States. In Manitoba the drift is found as unmodified till, moraines, outwash deposits and lake clay deposits of glacial Lake Agassiz, which developed against the face of the retreating ice-sheet. Also remaining are the elevated beaches of glacial Lake Agassiz. The Birds Hill gravel deposit near Winnipeg is a feature unusual to the surrounding countryside. It is of interest academically as to origin, and also commercially...