Distribution of Ribbed Moraine in the Lac Naococane Region, Central Québec, Canada

Abstract

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Ribbed moraines are large subglacially formed transverse ridges that cover extensive areas of the beds of the former Laurentide, Fennoscandian and Irish ice sheets. Since the flow speeds and stability of ice sheets are known to be sensitive to conditions operating at the bed, a full understanding of the processes of ribbed moraine genesis are critical if we are to appreciate their role in ice sheet dynamics. To date, advances in knowledge on how ribbed moraines are formed rely on inferences drawn from their characteristics. However, this approach is problematic given that ribbed moraine characteristics are poorly known. Scrutiny of the literature reveals that detailed observations are limited to small areas and rely on small sample sizes. Thus, generalisations drawn from this base cannot be regarded as being representative and remain an inadequate data source for testing the various hypotheses. The map forms part of a large study that investigated ribbed moraine characteristics in Ireland, Canada and Sweden over a combined area of 81,000 km² that has addressed this deficit. It shows the distribution of ribbed moraine ridges in the Lac Naococane region, central Québec and covers an area of 32,400 km². It comprises over 12,800 individual ridges and forms part of a database of over 33,000 individually mapped landforms which reveal ribbed moraine characteristics to be more complex than has hitherto been reported.