Surface form of the southern Laurentide Ice Sheet and its implications to ice-sheet dynamics

Research Article| May 01, 1992 Surface form of the southern Laurentide Ice Sheet and its implications to ice-sheet dynamics 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 Author and Article Information PETER U. CLARK 1Department of Geosciences, Oregon State University, Corvallis, Oregon 97331-5506 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1992) 104 (5): 595–605. https://doi.org/10.1130/0016-7606(1992)104<0595:SFOTSL>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; Surface form of the southern Laurentide Ice Sheet and its implications to ice-sheet dynamics. GSA Bulletin 1992;; 104 (5): 595–605. doi: https://doi.org/10.1130/0016-7606(1992)104<0595:SFOTSL>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 Reconstructions of the ice-surface morphology of several lobes of the southern Laurentide Ice Sheet reinforce previous arguments that this sector of the ice sheet was thin and low sloping. Driving stresses, estimated from the geometry of the reconstructed ice surfaces, are 0.7-4.3 kPa for the 14 ka Des Moines Lobe, 0.9-1.2 kPa for the 14 ka James Lobe, 0.9-1.7 kPa for the 18-20 ka Lake Michigan Lobe, 1.8-2.9 kPa for the 15-18 ka Chippewa Sublobe, and 17-22 kPa for the 15-18 ka Green Bay Lobe. Previous estimates of rates of ice-margin advance (450-2,000 m/yr) indicate moderate-to-fast ice velocities for the ice lobes. Reconstructed driving stresses and velocity estimates of the Des Moines, James, and Lake Michigan Lobes are analogous to the distal ends ("ice Plains") of low-sloping (0.4 X 10-3) but fast moving (500 m/yr) West Antarctic ice streams, whose dynamics have been attributed to sliding and/or subglacial sediment deformation by pervasive shear. These reconstructions support recent models of the Laurentide Ice Sheet which include movement by sliding or by subglacial sediment deformation along its southern, western, and northwestern sectors; evidence for either mechanism should be represented in the sedimentologic and geomorphic records. Thin ice in these regions indicates that the Laurentide Ice Sheet contained less ice volume and represented less of an orographic obstacle to atmospheric circulation than has been considered in models of the ice sheet on a rigid bed with steep profiles. 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.