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.

Ice-free conditions in southwestern British Columbia at 16000 years BP

1988 ◽  
Vol 25 (6) ◽  
pp. 938-941 ◽  
Author(s):  
John J. Clague ◽  
Ian R. Saunders ◽  
Michael C. Roberts
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Radiocarbon Dates ◽  
Maximum Extent ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

New radiocarbon dates on wood from two exposures in Chilliwack valley, southwestern British Columbia, indicate that this area was ice free and locally forested 16 000 radiocarbon years ago. This suggests that the Late Wisconsinan Cordilleran Ice Sheet reached its maximum extent in this region after 16 000 years BP. The Chilliwack valley dates are the youngest in British Columbia that bear on the growth of the Cordilleran Ice Sheet.

Laurentide and montane glaciation along the Rocky Mountain Foothills of northeastern British Columbia

2007 ◽  
Vol 44 (4) ◽  
pp. 445-457 ◽  
Author(s):  
Jan M Bednarski ◽  
I Rod Smith
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Rocky Mountain ◽  
Laurentide Ice Sheet ◽  
Cosmogenic Dating ◽  
Surficial Geology ◽  
Continental Divide ◽  
Mountain Front ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

Mapping the surficial geology of the Trutch map area (NTS 94G) provides new data on the timing of continental and montane glaciations along the Foothills of northeastern British Columbia. Striated surfaces on mountain crests were dated to the Late Wisconsinan substage by cosmogenic dating. The striations were produced by eastward-flowing ice emanating from the region of the Continental Divide. This ice was thick enough to cross the main ranges and overtop the Rocky Mountain Foothill summits at 2000 m above sea level (asl). It is argued here that such a flow, unhindered by topography, could only have been produced by the Cordilleran Ice Sheet and not by local cirque glaciation. During this time, the Cordilleran Ice Sheet dispersed limestone and schist erratics of western provenance onto the plains beyond the mountain front. Conversely, the Laurentide Ice Sheet did not reach its western limit in the Foothills until after Cordilleran ice retreated from the area. During its maximum, the Laurentide ice penetrated the mountain valleys up to 17 km west of the mountain front, and deposited crystalline erratics from the Canadian Shield as high as 1588 m asl along the Foothills. In some valleys a smaller montane advance followed the retreat of the Laurentide Ice Sheet.

Coalescence of late Wisconsinan Cordilleran and Laurentide ice sheets east of the Rocky Mountain Foothills in the Dawson Creek region, northeast British Columbia, Canada

2016 ◽  
Vol 85 (3) ◽  
pp. 409-429 ◽  
Author(s):  
Adrian Scott Hickin ◽  
Olav B. Lian ◽  
Victor M. Levson
Keyword(s):  
British Columbia ◽  
Flow Direction ◽  
Ice Sheet ◽  
Rocky Mountain ◽  
Ice Flow ◽  
Oxygen Isotope Stage ◽  
Digital Elevation ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
River Valleys

Geomorphic, stratigraphic and geochronological evidence from northeast British Columbia (Canada) indicates that, during the late Wisconsinan (approximately equivalent to marine oxygen isotope stage [MIS] 2), a major lobe of western-sourced ice coalesced with the northeastern-sourced Laurentide Ice Sheet (LIS). High-resolution digital elevation models reveal a continuous 75 km-long field of streamlined landforms that indicate the ice flow direction of a major northeast-flowing lobe of the Cordilleran Ice Sheet (CIS) or a montane glacier (>200 km wide) was deflected to a north-northwest trajectory as it coalesced with the retreating LIS. The streamlined landforms are composed of till containing clasts of eastern provenance that imply that the LIS reached its maximum extent before the western-sourced ice flow crossed the area. Since the LIS only reached this region in the late Wisconsinan, the CIS/montane ice responsible for the streamlined landforms must have occupied the area after the LIS withdrew. Stratigraphy from the Murray and Pine river valleys supports a late Wisconsinan age for the surface landforms and records two glacial events separated by a non-glacial interval that was dated to be of middle Wisconsinan (MIS 3) age.

Quaternary stratigraphy and history, Williams Lake, British Columbia

1987 ◽  
Vol 24 (1) ◽  
pp. 147-158 ◽  
Author(s):  
John J. Clague
Keyword(s):  
British Columbia ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Stream Channels ◽  
Valley Fill ◽  
Braided Streams ◽  
History Of ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Sand And Gravel

Thick valley-fill sediments in the vicinity of Williams Lake, British Columbia, provide a detailed record of the late Quaternary history of an area near the centre of the former Cordilleran Ice Sheet. Stratigraphic units assigned to the late Wisconsinan Fraser Glaciation, the preceding (penultimate) glaciation, and the present interglaciation are described. Especially noteworthy are (1) thick units of sand and gravel deposited by braided streams, perhaps during periods of ice-sheet growth; and (2) complex glaciolacustrine sediments that accumulated in ice-dammed lakes during periods of deglaciation.Glaciers from the Coast and Cariboo mountains coalesced and flowed north over central British Columbia during late Wisconsinan time. Fraser Glaciation advance sediments and older Pleistocene deposits were partially removed by this ice sheet, and the eroded remnants were mantled with till. At the end of the Fraser Glaciation, the Cordilleran Ice Sheet downwasted and retreated southward along an irregular front across the study area. Parts of the ice sheet stagnated and disintegrated into tongues confined to valleys. Sediment carried by melt streams flowing from decaying ice masses was deposited in glacial lakes, in stream channels, and on floodplains.

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.

Stratigraphy and Paleoecology of Pleistocene Interstadial Sediments, Central British Columbia

1990 ◽  
Vol 34 (2) ◽  
pp. 208-226 ◽  
Author(s):  
John J. Clague ◽  
Richard J. Hebda ◽  
Rolf W. Mathewes
Keyword(s):  
British Columbia ◽  
Boreal Forest ◽  
Ice Sheet ◽  
River Valley ◽  
Older Age ◽  
Time Interval ◽  
Spruce Forest ◽  
Tephra Layers ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

AbstractTwo exposures of organic-rich interstadial sediments in central British Columbia provide information on middle Wisconsinan environments and climates near the center of the region subsequently covered by the late Wisconsinan Cordilleran Ice Sheet. Interstadial sediments at Bullion Pit overlie drift of early Wisconsinan or older age and underlie thick drift of late Wisconsinan age. Alluvium (or colluvium) and peat were deposited on the floor of the ancestral Quesnel River valley 46,000–40,000 14C yr ago when the vegetation consisted of spruce forest with dry openings and local fens and the climate was colder and perhaps drier than today. This is broadly consistent with paleoclimatic reconstructions for the same time interval for Babine Lake, 400 km to the northwest, and for Meadow Creek, 400 km to the southeast. Plant-rich pond sediments containing tephra layers and vertebrate remains are exposed between two drifts in a ravine at Mexican Hill, 30 km east of Quesnel. Although they may be contemporaneous with the Bullion Pit beds, the nonglacial sediments at Mexican Hill more likely were deposited sometime after the warmest part of the last interglaciation, but prior to 50,000 yr B.P. At that time, the vegetation at Mexican Hill probably was parkland. The present vegetation at Mexican Hill is boreal forest; thus, a drier and possibly cooler climate is indicated.

Vashon Drift: definition of the formation in the Georgia Depression, southwest British Columbia

1985 ◽  
Vol 22 (5) ◽  
pp. 748-757 ◽  
Author(s):  
Stephen R. Hicock ◽  
John E. Armstrong
Keyword(s):  
British Columbia ◽  
Ice Sheet ◽  
Southwestern Part ◽  
Maximum Expansion ◽  
Source Areas ◽  
Alpine Glaciers ◽  
Time Space ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Definition Of

Vashon Drift was deposited during the Fraser Glaciation (late Wisconsinan) at the time of maximum expansion of the southwestern part of the Cordilleran ice sheet when it filled the Georgia Depression about 14 500 years ago. The drift is present throughout the depression and comprises till and glaciofluvial and glaciolacustrine sediments derived from source areas surrounding the coastal trough. It is overlain by Capilano Sediments and underlain by Quadra Sand, also of Fraser age. Drift deposition was diachronous and complex, probably caused by alpine glaciers coalescing in the trough with the ice margin repeatedly grounding and floating in seawater. Studies of bedrock striae, till fabrics, and clast provenance reveal that Vashon ice movement was generally southward, although locally controlled by topography. A time–space diagram is presented that confirms the long-held hypothesis that advance and decay of Vashon ice were rapid.

The Late Wisconsinan deglacial history of the east-central Taseko Lakes area, British Columbia

1997 ◽  
Vol 34 (11) ◽  
pp. 1509-1520 ◽  
Author(s):  
David H. Huntley ◽  
Bruce E. Broster
Keyword(s):  
British Columbia ◽  
Phase Iii ◽  
Fraser River ◽  
Glacial Lakes ◽  
East Central ◽  
Valley Fill ◽  
Drainage Patterns ◽  
History Of ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

Late Wisconsinan Fraser Glaciation retreat-phase deposits and landforms in the east-central Taseko Lakes area, British Columbia, are used to demonstrate a four-phase model of deglaciation. During phase I, at the onset of ice retreat, the Cordilleran Ice Sheet occupied much of the study area, blocking southward drainage of Fraser River. Phase II was marked by the deglaciation of uplands and plateaux. Meltwater drainage patterns were controlled by stagnating glaciers confined to valleys. Phase III commenced as remnant ice in the Fraser Valley downwasted to between 850 and 760 m elevation. At this time, interlobate glacial lakes formed in hanging valleys east of Fraser River. Drainage of glacial lakes occurred subglacially, and was accompanied by disintegration of remnant ice and an increase in mass movements in valleys. These events were followed by decreased sedimentation rates, reflecting lower meltwater volumes and exhaustion of unstable glacial debris during phase IV. Postglaciation valley fill was subject to fluvial degradation and terracing as modern drainage patterns became established.

Glacial Lake Camelsfoot: a Late Wisconsinan advance stage proglacial lake in the Fraser River valley, Gang Ranch area, British Columbia

1994 ◽  
Vol 31 (5) ◽  
pp. 798-807 ◽  
Author(s):  
David H. Huntley ◽  
Bruce E. Broster
Keyword(s):  
British Columbia ◽  
Glacial Lake ◽  
Fraser River ◽  
Ice Flow ◽  
Lake System ◽  
Reference Sections ◽  
Lithostratigraphic Units ◽  
Proglacial Lake ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

In the Gang Ranch area, British Columbia, interaction between the regional physiography and ice flow during the Late Wisconsinan Fraser Glaciation resulted in the formation of a proglacial lake confined to valleys of the Fraser River and its tributaries. Lithostratigraphic and geomorphic evidence suggests that ponding was initiated in the Big Bar Creek area where the Fraser River is confined to a deep canyon in the Camelsfoot Range. During ice advance, a proglacial lake system developed that progressively deepened and reached a minimum upper elevation of approximately 710 m asl prior to being overridden by ice. We propose that this system be formally named "Glacial Lake Camelsfoot." A composite stratotype, comprising lithostratigraphic units associated with Glacial Lake Camelsfoot, is described from eight reference sections along Fraser River, Churn, and Lone Cabin creeks in the Gang Ranch area. Additional geomorphic evidence indicates that at the Fraser Glaciation maximum, the Cordilleran Ice Sheet in the study area ranged from 600 to 2000 m in thickness.

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