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The pattern and style of deglaciation at the late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia

David H. Huntley, Adrian S. Hickin and Olav B. Lian
The pattern and style of deglaciation at the late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (January 2017) 54 (1): 52-75

Abstract

This paper reports on the landform assemblages at the northern confluence of the Late Wisconsinan Laurentide and Cordilleran ice sheets with montane and piedmont glaciers in the northern Rockies and southern Mackenzie Mountains. Recent observations in northeastern British Columbia refine our knowledge of the pattern and style of ice sheet retreat, glacial lake formation, and meltwater drainage. At the onset of deglaciation, confluent Laurentide and Cordilleran terminal ice margins lay between 59 degrees N, 124 degrees 30'W and 60 degrees N, 125 degrees 15'W. From this terminal limit, ice sheets retreated into north-central British Columbia and Yukon Territory, with remnant Cordilleran ice and montane glaciers confined to mountain valleys and the Liard Plateau. Distinctive end moraines are not associated with the retreat of Cordilleran ice in these areas. Laurentide ice retreated northeastward from uplands and the plateaus; then separated into lobes occupying the Fort Nelson and Petitot river valleys. Ice-retreat landforms include recessional end moraines (sometimes overridden and drumlinized), hill-hole pairs, crevasse-fill deposits, De Geer-like ribbed till ridges, hummocky moraines, kames, meltwater features, and glacial lake deposits that fall within the elevation range of glacial Lake Liard and glacial Lake Fort Nelson (ca. 840-380 m). Meltwater and sediment transport into glacial lakes Fort Nelson, Liard, Nahanni, and Mackenzie was sustained by remnant ice in the Liard River and Fort Nelson River drainage basins until the end of glaciation. Optical dating of sand from stabilized parabolic dunes on the Liard Plateau indicates that proglacial conditions, lake formation, and drainage began before 13.0 + or - 0.5 ka (calendar years). The Petitot, Fort Nelson, and Liard rivers all occupy spillways incised into glacial deposits and bedrock by meltwater overflow from glacial lakes Peace and Hay.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 54
Serial Issue: 1
Title: The pattern and style of deglaciation at the late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia
Affiliation: Geological Survey of Canada, Pacific Division, Vancouver, BC, Canada
Pages: 52-75
Published: 201701
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 140
Accession Number: 2017-025628
Categories: Quaternary geologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 2 tables, geol. sketch maps
N59°00'00" - N60°00'00", W126°00'00" - W122°00'00"
Secondary Affiliation: British Columbia Geological Survey, CAN, CanadaUniversity of the Fraser Valley, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201716
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