Geology of Saskatchewan - Quaternary Period

Quaternary Period

During the Quaternary period, between 2 to 3 million years ago, the prairies were covered by a glacier, the Laurentide ice sheet.

It was 3 kilometers (1.9 mi) thick which advanced and receded several times across the prairies. There were four major glacial stages of the current ice age affecting the Saskatchewan area, the Nebraskan, Kansan, Illinioan, and Wisconsin Ice age. The newest of geological events occurred during the Quaternary period when comprises the last two million years. Northern Saskatchewan and the shield area shows the effects of glacial erosion and scour; the Western Canada Sedimentary Basin is a location of glacial deposition and collection. In southern Saskatchewan there are late Pliocene, pre-Illinoian continental glaciation sand and gravel deposits left behind from water deposition (alluvial) and glacial edge deposits (colluvial). By the study of till, terrain, the limits of the Illinoian glaciation are evidenced around Willow Bunch Lake, Wood Mountain, Cypress Hills area.

The melting glaciers left behind sand and, silt outwash plains. The Great Sand Hills of Saskatchewan are evidence of winds and sand storms which have accumulated the sands left behind. Retreating glaciers left meltwater which pooled in lakes.

Glacial Lake Regina covered south-central area, and Glacial Lake Agassiz covered much of Saskatchewan and neighboring regions of the US and Manitoba. The ice and water retreated, and the lake beds formed flat plains. The land exposed from under the ice sheets was rubble, and ridges of gravel.