Delineation of Paleowind Direction from Dunes in Simcoe County, Ontario

Abstract

Dune fields that developed along paleolake shorelines in Ontario are a product of paleoenvironmental conditions, which developed as a result of glacially influenced geological processes. In Simcoe County, Ontario, many dune fields were created between 3 and 12 ka, when this area was covered by a series of lakes, bordered by thick sandy beaches. Coastal sediments of the glacial Lake Algonquin and the Nipissing phase of the upper Great Lakes were reworked primarily by paleowind activity and intense periodic storms once lake levels had decreased. This formed dunes, which are now common along the south-eastern coast of Georgian Bay in Simcoe County. Dunes that developed earlier (8–10 ka) have a different average orientation than dunes that developed later (3–5 ka). Various geomorphometric techniques are tested to construct a replicable methodology for determining paleowind direction. Through identification of parabolic dunes, azimuth angles were determined and used to infer the dominant paleowind directions. Dunes on the paleolake Algonquin plain commonly have a north-east to south-west orientation, whereas dunes associated with Nipissing phase shorelines formed via north-westerly winds. These data may suggest changing prevailing winds in the Great Lakes region during deglaciation.