CGRG Bibliography of Canadian Geomorphology
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Author : Barrie, J.V.; Lewis, C.F.M.; Fader, G.B.; King, L.H.; and Amos, C.L.
Date : 1982.
Title : Seabed processes on the northeastern Grand Banks : modern reworking of relict sediments
Publication : Paper presented at the Eleventh International Congress on Sedimentology, McMaster University, Hamilton, Ontario, August 22-27, 1982.
Issue :
Page(s) :
Abstract
The northeastern edge of the Grand Banks supports a series of bathymetrically controlled sediment facies ranging up-slope between 140 and 70 m, unconformably overlying a Tertiary base of siltstones and sandstones. Below 90 m the facies range from continuous fine sand, through lag gravel and sand ribbons, with arcuate sand waves and megaripples normal to the axis of the ribbons. Above 90 m alternating sand bars (sand ridges?) up to 3 m in height and lag gravels occur on a terrace of well sorted, medium sand and rounded pebbles. Megaripples and arcuate sand waves (400 m wave-length) with megaripples on the stoss side are developed on the terrace. The regional geology suggests that many of the surface sediments were inherited from Pleistocene deposits subsequently reworked in coastal environments by the early Holocene transgression. Recent side scan sonar surveys and bottom photography demonstrate intermittent modern sediment transport. Inparticular, photographs show asymmetrical ripples in well sorted sand after seasonal storms. Side scan sonar coverage in the Hibernia area shows fields of two and three dimensional megaripples (5 m length) which appear to be migrating across trawl marks left by fishing operations. These sedimentary bedforms are attributed to unidirectional storm driven currents, ocean currents and extreme waves. The larger bedforms may reflect paleo-oceanographic conditions while the small bedforms appear to be modern.
Bibliography of Canadian Geomorphology