CGRG Bibliography of Canadian Geomorphology
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Author : Davidson-Arnott, R.G.; and Langham, D.R.J.
Date : 1995
Title : The role of softening in erosion of the nearshore profile on a cohesive coast
Publication : Proceedings, 1995 Canadian Coastal Conference. Ottawa: National Research Council
Issue :
Page(s) : 799-814
Abstract
Recent work has recognised that vertical erosion (lowering) of the nearshore profile is a major control on the rate of recession of bluffs on cohesive coasts. Where the nearshore profile is developed in over consolidated till, as is the case in many mid- and high-latitude cohesive shorelines, the strength of the till generally exceeds the fluid forces associated with wave orbital motion and nearshore currents. However, it has been suggested that softening of the till can reduce the strength of the material and thus increase the potential for erosion to occur. Measurement of the shear strength of till were carried out along a 300 m long under,water profile on a cohesive shoreline near St. Catharines, Lake Ontario. Changes in shear strength were monitored over a four month period in 1994 in experimental plots set up in water depths of 1.6 m, 3.5 m, and 4.75 m and were compared to measurements of vertical erosion of the till surface. There was considerable decrease in shear strength of the surface of the exposed till during periods of low wave activity. Periods of high wave activity resulted in the removal of a layer of softened material, thus exposing the underlying harder till. The results suggest that the thickness of material eroded during any storm event is directly related to the thickness of the softened layer that develoops during non-storm periods.
Bibliography of Canadian Geomorphology