CGRG Bibliography of Canadian Geomorphology
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Author : Douma, M.; and Aylsworth, J.M.
Date : 2001.
Title : High-resolution sonar profiling of glacial and postglacial sediments in the Ottawa River near L'Orignal, Ontario.
Publication : Geological Survey of Canada, Current Research
Issue : 2001-D4.
Page(s) : 19 p.
Abstract
In 1999, a high-resolution sub-bottom sonar survey in the Ottawa River, 5 km west of L'Orignal, Ontario, indicated faulted Champlain Sea sediments. In 2000, detailed grid surveys consisting of 42 line kilometres of single-channel sub-bottom sonar data were conducted to outline the extent of the faulted areas. A rotated block of sediment, 130 m by 200 m and up to 25 m thick, was discovered to have rotated about 15 degrees. Smaller rotated sections, and areas of differential compaction occur along strike from the large rotated block. Small independently rotated blocks also occur nearby. Faulting and rotation of sediments is attributed to earthquake shaking. Seismic liquefaction of sediment leading to the development of excess pore pressure may have caused an initial failure along a single glide plane, which subsequently propagated upward in a curving path, through the overlying layers, to form a spoon-shaped slip plane.
Bibliography of Canadian Geomorphology