CGRG Bibliography of Canadian Geomorphology
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Author : Cameron, G.D.M.; and King, E.L.
Date : 2007.
Title : The Gully: a Late Quaternary history of a submarine canyon.
Publication : CANQUA Ottawa 2007. Canadian Quaternary Association Conference, June 4-8, 2007. Carleton University, Ottawa, Ontario, Canada.
Issue :
Page(s) :
Abstract
The Gully is the largest submarine canyon complex on the southeastern Canadian continental margin and the first marine protected area mapped by the Geological Survey of Canada. A distinct glacial imprint of the deeply eroded Cenozoic mudstone and sandstone morphology in The Gully imparts some unique constraints on the process and timing of canyon evolution. The inner and outer parts of The Gully have contrasting morphologies that reflect the glaciated (inner) vs. non-glaciated (outer) processes. The outer Gully is characterized by ridge and valley morphology that represents the culmination of glacial and low-stand canyonization processes. The inner Gully is characterized by a meandering main thalweg, large feeder channels and retrogressive slumped canyon walls with terraces. Low-relief moraines confirm that glacial ice occupied most of the upper Gully to at least the outermost moraine and likely represent the last glacial maximum. The Gully morphology steered streaming ice, with a low ice profile, that did not overtop the western flank, leaving a limited ice-free area on the bank. The pre-existing inner Gully morphology was smoothed by glacier sole erosion and partially infilled and healed the rough terrain by subglacial and proglacial sediments. Renewed canyonization was concurrent with, and followed by, sandy glacimarine deposition. Turbidities, retrogressive mass-failures and associated debris flows reshaped the inner Gully morphology. Sandy turbidities eroded soft glacial marine sediment, infilling the upper western flanks of The Gully, allowing the erosional growth of major side canyons. A succession of glacial derived bank edge sandy clinoforms to the west fed these side canyons in at least two major phases. Early post-glacial and Holocene age sand transport modified these major side canyons, most of which continue to be sediment pathways into The Gully from Sable Island Bank. Sand influx, derived from sub-littoral erosional processes, continues to enter the canyon from the floor of the upper reaches of The Gully.
Bibliography of Canadian Geomorphology