The Early Wisconsinan History of the Laurentide Ice Sheet

Abstract

La calotte glaciaire laurentidienne Volume 41, numéro 2, 1987 URI : id.erudit.org/iderudit/032679ar

Deglaciation of the Laurentide Ice Sheet from the Last Glacial Maximum

“…St-Onge, 1987), and likely existed only as a small, thin ice sheet over the original inception grounds in north-eastern Canada by ~80 ka (MIS 5a) (Marshall et al, 2000;Stokes et al, 2012). Thereafter, the LIS is thought to have grown rapidly during MIS 4, reaching a maximum extent around 65 ka (Vincent and Prest, 1987;Marshall et al, 2000;Kleman et al, 2002;Stokes et al, 2012), which coincides with the oldest recognised Heinrich event (H6) and a marked increase in ice-rafted debris from that time (Kirby and Andrews, 1999;Hemming, 2004, Bassis et al, 2017.…”

“…It is thought that an embryonic dome formed over Labrador during MIS 5d (cf. Andrews and Mahaffy, 1976;Boulton et al, 1985;Vincent and Prest, 1987;Clark et al, 1993;Marshall et al, 2000;Kleman et al, 2010), possibly as early as 116-114 ka, and with some modelling (Stokes et al, 2012) indicating a large but thin ice sheet at 110 ka that covered 70-80% of the area occupied by the MIS 2 ice sheet (see also Vincent and Prest, 1987;Boulton and Clark, 1990a, b;Clark et al, 1993). This "explosive ice sheet growth" (Marshall, 2002: p. 133) during MIS 5d is consistent with records of a rapid fall in global sea level around that time (Marshall et al, 2000;Cutler et al, 2003), but some workers suggest more minimal ice volumes in North America (~2-3 m of sea level equivalent: Kleman et al, 2002) and that the LIS did not grow substantially until MIS 4 (e.g.…”

Laurentide Ice-Flow Patterns: A Historical Review, and Implications of the Dispersal of Belcher Islands Erratics

“…Also the Labrador ice may have developed over northern Ontario prior to infilling of Hudson Bay proper thus necessitating even thicker ice in Hudson basin prior to the development of the regional southwest flow over northern Ontario (see Glacial Map of Canada, Prest et al, 1968). The presumed growth of Early Wisconsinan ice as above mentioned is illustrated in Vincent and Prest (1987). Northwest and west-trending striae in northern Ontario, that pre-date the Late Wisconsinan southwest flow, have been observed over a wide area (Prest, 1963 Fig.…”

“…1898 Low, 1902Chamberlin, 1907Chamberlin, 1913Tyrrell, 1913Martin, L., 1914, 1916Coleman, 1922Coleman, 1926Alden, 1924Martin, 1932, 1935Flint, 1943MacLean, 1944Glacial Map of North America 1945. 1949Wickenden, 1947Prest, 1957Ives, 1957Sim, 1960Mackay, 1960Ives & Andrews, 1963Prest, 1967Flint, 1971 Mayewskief a/., 1981 Dyke era/., 1982Prest, 1983, 1984Fisher et al, 1985Vincent & Prest. 1987Occhietti, 1987Dyke & Prest, 1987 (Fig.…”

Applying the Cosmogenic Nuclide Dipstick Model for Deglaciation of Mt. Washington

“…The more weathered lower till deposits underlying late Wisconsinan (Marine Isotope Stage (MIS) 2) deposits is less common in New England, but occurrences have been described from the Boston Harbor drumlins, Massachusetts (Kaye, 1961), Nash Stream, New Hampshire (Koteff and Pessl, 1985), and New Sharon, Maine (Caldwell, 1986;Weddle, 1989), but its age remains unknown. The lower till's age was originally assigned to the early Wisconsinan (MIS 4) (Borns and Calkin, 1977;Stone and Borns, 1986;Vincent and Prest, 1987), but others have suggested the lower till is more likely Illinoian (MIS 6) or older due to radiometric dating and amino acid racemization age estimates on detrital coral from the upper part of the Sankaty Head on Nantucket Island, MA (Oldale, 1982;Oldale and Colman, 1992). In addition, ice volume estimates from oxygen isotope and sea level records indicate ice was less extensive during the early Wisconsinan than the late Wisconsinan, possibly suggesting that the LIS did not extend as far south as New England then (Oldale and Colman, 1992;Lambeck et al, 2014).…”