Recent modifications to the Trans-Canada Highway approximately 65 km west of Calgary, Alberta, exposed deep sections through a series of elliptical ridges. These features had been variously described as moraines, drumlins, and crevasse-fillings. On the basis of field and laboratory evidence, it is concluded that the ridges are drumlins which formed by a process of basal accretion beneath ice of the Bow Valley glacier. Variations in ridge morphology are attributed partly to postdepositional deformation, and partly to dynamic conditions prevailing in the ice at the time of formation.

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