Abstract

Evidence of three major ice movements in the Asbestos area of southern Quebec is based exclusively on crag-and-tail glacial striations that have been measured on horizontal or subhorizontal bedrock surfaces. Cross-cutting glacial striations indicate early southeastward movement that was followed, as this portion of the ice sheet thinned by melting in late-glacial time, by a northward flow of the ice down the regional topography toward the valley of the St. Lawrence River, and finally, as the ice thinned further, was followed by a more local but prominent westward ice displacement down the local slope toward the valley of the St. Francis River. The ice mass that flowed northward and then westward is believed to have been separated from the main ice sheet and was left free to flow down the northward-sloping and, more locally, westward-sloping surfaces, causing the observed glacial abrasion.

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