Subglacial drainage, eskers, and deforming beds beneath the Laurentide and Eurasian ice sheets

Abstract

Research Article| February 01, 1994 Subglacial drainage, eskers, and deforming beds beneath the Laurentide and Eurasian ice sheets PETER U. CLARK; PETER U. CLARK 1Department of Geosciences, Oregon State University, Corvallis, Oregon 97331-5506 Search for other works by this author on: GSW Google Scholar JOSEPH S. WALDER JOSEPH S. WALDER 2U. S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Search for other works by this author on: GSW Google Scholar Author and Article Information PETER U. CLARK 1Department of Geosciences, Oregon State University, Corvallis, Oregon 97331-5506 JOSEPH S. WALDER 2U. S. Geological Survey, Cascades Volcano Observatory, 5400 MacArthur Boulevard, Vancouver, Washington 98661 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1994) 106 (2): 304–314. https://doi.org/10.1130/0016-7606(1994)106<0304:SDEADB>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 Email Permissions Search Site Citation PETER U. CLARK, JOSEPH S. WALDER; Subglacial drainage, eskers, and deforming beds beneath the Laurentide and Eurasian ice sheets. GSA Bulletin 1994;; 106 (2): 304–314. doi: https://doi.org/10.1130/0016-7606(1994)106<0304:SDEADB>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 Glaciological theory predicts that the subglacial drainage network at the base of gently sloping ice sheets resting on deforming sediment should consist of many wide, shallow, probably braided "canals" distributed along the ice-sediment interface, rather than an arborescent network of relatively few large tunnels, as would develop over a rigid substrate. A corollary prediction examined here is that eskers, which form in large subglacial tunnels, should be rare where subglacial bed deformation occurred, but they may be relatively common where the bed was rigid. Bed deformation would be most likely where subglacial till was relatively continuous, fine-grained, and of low permeability—that is, in regions where till is derived primarily from underlying sedimentary bedrock—but unlikely where discontinuous, coarse-grained, high-permeability till was derived from underlying crystalline bedrock. The observed distribution of eskers in areas covered by the Laurentide and Eurasian (British, Scandinavian, and Barents Sea) ice sheets during the last glaciation shows that most eskers occur over crystalline bedrock overlain by discontinuous, high-permeability till, but are rare or absent over sedimentary bedrock overlain by fine-grained, low-permeability till, thus matching reasonably well our prediction. Glaciological theory and geologic evidence indicate that esker systems on a subcontinental scale are time-transgressive. Sedimentological evidence for a "canal" drainage system appears to be present in fine-grained tills where eskers are largely absent. 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.