Abstract

A variety of p-forms are discussed in terms of the agent producing them. A general conclusion based on form and the location of striations relative to p-forms is that they are produced by meltwater rather than ice. Erosional marks in the Wilton Creek valley, Ontario, are different from earlier described p-forms. Their relationship to striations establishes them as being of subglacial origin, and their form similarity with flutes together with the partial or total absence of striations on them suggests a fluvial origin. Large-scale forms are interpreted as spindle-shaped flutes associated with flow separation. Small-scale forms are subdivided into straight spindle forms, curved spindle forms, braided forms, and scallops. They appear not to have followed the inverse relationship between size and flow velocity reported for some other erosional marks. Potential but speculative explanations for these small-scale forms are that they are related to Taylor–Görtler vortices, vortices on mixing layers, or trailing vortices behind bluff obstacles. A general conclusion is that the forms described indicate broad separation by meltwater of the glacier from its bed.

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