Erosion of bedrock by subglacial meltwater, Cantley, Quebec

Abstract

Research Article| August 01, 1989 Erosion of bedrock by subglacial meltwater, Cantley, Quebec DAVID R. SHARPE; DAVID R. SHARPE 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8 Search for other works by this author on: GSW Google Scholar JOHN SHAW JOHN SHAW 2Department of Geography, Queen's University, Kingston, Ontario K7L 3N6 Search for other works by this author on: GSW Google Scholar Author and Article Information DAVID R. SHARPE 1Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8 JOHN SHAW 2Department of Geography, Queen's University, Kingston, Ontario K7L 3N6 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1989) 101 (8): 1011–1020. https://doi.org/10.1130/0016-7606(1989)101<1011:EOBBSM>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DAVID R. SHARPE, JOHN SHAW; Erosion of bedrock by subglacial meltwater, Cantley, Quebec. GSA Bulletin 1989;; 101 (8): 1011–1020. doi: https://doi.org/10.1130/0016-7606(1989)101<1011:EOBBSM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Several erosional forms on bedrock at Cantley, Quebec, differ from well-known glacial abrasion forms. The forms consist of obstacle marks, hollows, depressions, and channels, which are defined by sharp rims, smooth inner surfaces, divergent flow features, and remnant ridges. These forms are found on lee, lateral, and overhung rock surfaces. This assemblage of features is best explained by differential erosion produced by separation eddies along lines of reattachment. Rapid, sediment-laden, turbulent, subglacial melt-water flows likely produced the forms by corrasion and cavitation erosion.Sculpted fluvial forms in terrain subject to flooding in Australia are identical to some of the Cantley forms which confirms their formation by water erosion. Although glacial abrasion may not be eliminated as an explanation for sculpted forms, it is not necessary.Ice-abrasion forms, such as striations, and such plucked forms as gouges and crescentic fractures are also present at the Cantley site. Pitted forms, polishing, and carbonate precipitate are also found. The occurrence of abrasion, pitting, polishing, and carbonate precipitate with meltwater forms suggests that the meltwater flows were subglacial. Decoupling of abrading ice from its bed temporarily suspended glacial abrasion, whereas reattachment of ice to the bed may have led to the rounding of sharp edges and the production of striations superposed on the glacifluvial forms.The association of forms produced both by glacifluvial erosion and ice abrasion suggests that the glacier was alternately lifted from, and reattached to, the bed during periodic subglacial floods. These floods may have affected the dynamics of the ice sheet, and depositional sequences related to catastrophic meltwater outbursts probably were laid down in adjacent basins. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.