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

• Main Authors: Huntley, David H., Hickin, Adrian S, Lian, Olav B.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2016
• Subjects: Fort Nelson; Fort Nelson River; Glacial Lake; Liard; Liard Plateau; Northern Rockies; Yukon; Ice Sheet; Liard River; Mackenzie mountains
• Online Access: http://hdl.handle.net/1807/74519; http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2016-0066

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 59oN, 124o30â W and 60oN, 125o15â 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 to 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 Âą 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. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.