Striations, giant grooves, and superposed drag folds, Interlake area, Manitoba

Abstract
Cross-cutting relationships of glacial striations on carbonate bedrock, in the Steep Rock – Gypsumville district, Manitoba, suggest movement of glacier ice generally to the southeast followed by movement generally to the west or southwest.These two major sets of striations have orientations similar to those of linear topographic depressions and ridges of low relief, which are conspicuous on airphotos. Although in glacial drift, the surface grooves overlie grooves in bedrock which apparently are the result of glacial erosion. The topographic grooves and intervening ridges resemble features described from other parts of the Lake Agassiz Plain, and have been assigned a variety of origins. The surface grooves cannot be correlated in trend to joints in bedrock.Two major sets of superposed folds are exposed in gypsum at Gypsumville and in carbonates at Spearhill. The similarities between the folds, in the gypsum and the carbonates, suggest that they have a common origin. The trends of the axial planes of the two sets of folds are approximately perpendicular to the two major trends of glacial striations and surface grooves. Glacial drag is the most probable cause of folding in both gypsum and limestone.