CGRG Bibliography of Canadian Geomorphology
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Author : Dionne, J.-C.
Date : 1988
Title : Ploughing boulders along shorelines, with particular reference to the St. Lawrence Estuary.
Publication : Geomorphology
Issue : 1(4):
Page(s) : 297-308
Abstract
Ploughing boulders are defined as large stones moved by drift ice with a ploughing action into the substrate, leaving a linear depression on the back and building a frontal push ridge. They are commonly found on unconsolidated tidal flats and on rock shore platforms along cold-region shorelines in the marine, lacustrine and fluvial environments. It is an erosional process of great significance, particularly for consolidated substrates. A total of 176 ploughing boulders were measured in eighteen localities along the St. Lawrence estuary. The largest boulder weighed 176 tons and was moved 3 m, while a 50 t boulder was moved 40 m. On shore platforms cut in shales, one boulder 49 t, has scoured a depression 19 m long and up to 40 cm deep, and built a frontal ridge 40 cm high. Along the St. Lawrence estuary about 95 of ploughing boulders were moved seaward by ice entrained by ebb currents.
Bibliography of Canadian Geomorphology