scholarly journals A Composite Profile of the Cordilleran Ice Sheet During Mcconnell Glaciation, Glenlyon and Tay River map Areas, Yukon Territory

1986 ◽  
Author(s):  
A Duk-Rodkin ◽  
L E Jackson ◽  
O Rodkin
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Cordilleran Ice Sheet

NORTHERN CORDILLERAN ICE SHEET DISPLAYS A DIACHRONOUS RESPONSE TO MIS 4 FORCING, YUKON TERRITORY,CANADA

2019 ◽  
Author(s):  
Brent C. Ward ◽  
◽  
Jeffrey D. Bond ◽  
Derek Cronmiller ◽  
Derek Turner ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Cordilleran Ice Sheet

Evidence for a 55–50 ka (early Wisconsin) glaciation of the Cordilleran ice sheet, Yukon Territory, Canada

2007 ◽  
Vol 68 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Brent C. Ward ◽  
Jeffrey D. Bond ◽  
John C. Gosse
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Canadian Cordillera ◽  
Aleutian Low ◽  
Climatic Forcing ◽  
Apparent Contrast ◽  
Oxygen Isotope Stage ◽  
Source Areas ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages

AbstractCosmogenic 10Be ages on boulders of 54–51 ka (n=4) on a penultimate Cordilleran ice sheet (CIS) drift confirm that Marine Oxygen Isotope Stage (MIS) 4 (early Wisconsin) glaciation was extensive in parts of Yukon Territory, the first confirmed evidence in the Canadian Cordillera. We name the glaciation inferred from the mapped and dated drift the Gladstone. These results are in apparent contrast to the MIS 6 (Illinoian) age of the penultimate Reid glaciation to the east in central Yukon but are equivalent to exposure ages on MIS 4 drift in Alaska. Contrasting penultimate ice extents in Yukon requires that different source areas of the northern CIS in Yukon responded differently to climatic forcing during glaciations. The variation in glacier extent for different source areas likely relates to variation in precipitation during glaciation, as the northern CIS was a precipitation-limited system. Causes for a variation in precipitation remain unclear but likely involve the style of precipitation delivery over the St. Elias Mountains possibly related to variations in the Aleutian low.

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

2017 ◽  
Vol 54 (1) ◽  
pp. 52-75 ◽  
Author(s):  
David H. Huntley ◽  
Adrian S. Hickin ◽  
Olav B. Lian
Keyword(s):  
British Columbia ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Yukon Territory ◽  
Glacial Lake ◽  
Glacial Lakes ◽  
Lake Formation ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Lake Deposits

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°N, 124°30′W and 60°N, 125°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 ± 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.

scholarly journals The Last Cordilleran Ice Sheet in Southern Yukon Territory

2007 ◽  
Vol 45 (3) ◽  
pp. 341-354 ◽  
Author(s):  
Lionel E. Jackson ◽  
Brent Ward ◽  
Alejandra Duk-Rodkin ◽  
Owen L. Hughes
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Eastern Coast ◽  
Small Magnitude ◽  
Ice Flow ◽  
Coast Mountains ◽  
Terminal Moraine ◽  
Ice Surface ◽  
Flow Surface ◽  
Cordilleran Ice Sheet

ABSTRACT The Cordilleran Ice Sheet in Yukon radiated from ice-divides in the Selwyn, PeIIy1 Cassiar, and eastern Coast Mountains and was contiguous with a piedmond glacier complex from the St. Elias Mountains. Expansion of glaciers in divide areas could have been underway by 29 ka BP but these did not merge to form the ice sheet until after 24 ka BP. The firn line fell to approximately 1500 m at the climax of McConnell Glaciation. Flow within the ice sheet was more analogous to a complex of merged valley glaciers than to that of extant ice sheets: topographic relief was typically equal to or exceeded ice thickness, and strongly influenced ice flow. Surface gradients on the ice sheet were fractions of a degree. Steeper ice-surface gradients occurred locally along the digitate ice margin. Retreat from the terminal moraine was initially gradual as indicated by recessional moraines within a few tens of kilometres of the terminal moraine. Small magnitude readvances occurred locally. The ice sheet eventually disappeared through regional stagnation and downwasting in response to a rise in the firn line to above the surface of the ice sheet. Regional déglaciation was complete prior to approximately 10 ka BP.

Late Wisconsinan glaciation of the Glenlyon Range, Pelly Mountains, Yukon Territory, Canada

1992 ◽  
Vol 29 (9) ◽  
pp. 2007-2012 ◽  
Author(s):  
Brent C. Ward ◽  
Lionel E. Jackson Jr.
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Ice Growth ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

Airphoto analysis, identification of erratics, and stratigraphic and geomorphic investigations were used to determine the nature of McConnell (Late Wisconsinan) age glaciation in the Glenlyon Range, Yukon Territory. Most of the peaks of the Glenlyon Range were nunataks within the Selwyn Lobe of the Cordilleran Ice Sheet. The configuration of local and Selwyn Lobe moraines indicates that local glaciers did not extend beyond the cirques and made no contribution to the Selwyn Lobe. These conclusions are confirmed by the character of sediments examined in sections along Little Sheep Creek and by the distribution of erratics in one of the cirque valleys. Aridity limited local ice growth; large glaciers did not grow because of insufficient precipitation.

RAPID RETREAT OF THE WESTERN MARGIN OF THE NORTHERN AND SOUTHERN CORDILLERAN ICE SHEET IN RESPONSE TO ABRUPT DEGLACIAL SEA-SURFACE TEMPERATURE WARMING

2017 ◽  
Author(s):  
Heather D. Bervid ◽  
◽  
Anders E. Carlson ◽  
Maureen H. Walczak ◽  
Ingrid Hendy ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Ice Sheet ◽  
Sea Surface ◽  
Western Margin ◽  
Cordilleran Ice Sheet ◽  
Surface Temperature Warming
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