scholarly journals The Cordilleran Ice Sheet and the Glacial Geomorphology of Southern and Central British Colombia

2007 ◽  
Vol 45 (3) ◽  
pp. 365-377 ◽  
Author(s):  
June M. Ryder ◽  
Robert J. Fulton ◽  
John J. Clague
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
Middle Pleistocene ◽  
Sea Level Changes ◽  
Coast Mountains ◽  
Glacial Sediments ◽  
Late Tertiary ◽  
British Colombia ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

ABSTRACT This paper reviews the current state of knowledge about the Cordilleran Ice Sheet in southern and central British Columbia. Reconstructions of the ice sheet and the styles of ice expansion and déglaciation are based on extensive and varied glacigenic sediments and landforms that date from Late Wisconsinan (Fraser) Glaciation. Late-glacial lakes and sea level changes are also described and related to isostatic and eustatic effects. The timing of ice expansion and recession during Fraser Glaciation was markedly asymmetric: ice build-up commenced about 29 000 years BP, culminated between 14 500 and 14 000 years BP1 and déglaciation was largely completed by 11 500 years BP. Most of this interval appears to have been dominated by montane glaciation, which produced striking erosional landforms. A Cordilleran Ice Sheet existed from only about 19 000 to 13 500 years BP. An older glaciation, probably of Early Wisconsinan age, has been recognized from widespread exposures of drift that underlies Middle Wisconsinan non-glacial sediments. Pre-Wisconsinan drift is present near Vancouver. Drifts of late Tertiary to Middle Pleistocene age have been dated by association with volcanic sequences in the southern Coast Mountains and the central Interior, and by paleomagnetic studies in the southern Interior.

scholarly journals The Cordilleran Ice Sheet in Northern British Colombia

2007 ◽  
Vol 45 (3) ◽  
pp. 355-363 ◽  
Author(s):  
June M. Ryder ◽  
Denny Maynard
Keyword(s):  
Early Phase ◽  
Ice Sheet ◽  
Drainage System ◽  
Ice Flow ◽  
Outlet Glacier ◽  
Radiocarbon Dates ◽  
Coast Mountains ◽  
British Colombia ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

ABSTRACT Dates from lavas associated with tills and erratics indicate that ice-sheet glaciations occurred between 4 and 0.6 Ma BP. The few radiocarbon dates that are available suggest that the chronology of the Late Wisconsinan (Fraser Glaciation) ice sheet of northern British Columbia was similar to that of the southern part of the province. During what may have been a long, early phase of this glaciation, Glacial Lake Stikine was dammed by advancing valley glaciers in the Coast Mountains, and alpine glaciers developed on the intermontane plateau. At the climax of Fraser Glaciation, ice-flow patterns were dominated by outflow from a névé centred over the northern Skeena Mountains. Déglaciation occurred partly by frontal retreat of ice tongues and partly by downwasting of stagnant ice. Recessional moraines mark one or more resurgences or stillstands of the ice margin. During déglaciation, Stikine River valley was occupied by an active outlet glacier and a major subglacial drainage system.

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.

Late Tertiary to late Quaternary record in the Mackenzie Mountains, Northwest Territories, Canada: stratigraphy, paleosols, paleomagnetism, and chlorine - 36

1996 ◽  
Vol 33 (6) ◽  
pp. 875-895 ◽  
Author(s):  
A. Duk-Rodkin ◽  
R. W. Barendregt ◽  
C. Tarnocai ◽  
F. M. Phillips
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Unconsolidated Sediments ◽  
Laurentide Ice Sheet ◽  
Stratigraphic Sequence ◽  
Late Tertiary ◽  
Mackenzie Mountains ◽  
Late Wisconsinan ◽  
Stratigraphic Succession

A stratigraphic sequence of unconsolidated sediments ranging in age from Late Pliocene to Late Pleistocene is recorded in the Canyon Ranges of the Mackenzie Mountains. Three of the sections (Katherine Creek, Little Bear River, and Inlin Brook) expose bedrock and Tertiary gravel overlain by colluvium and a multiple till sequence of montane origin, separated by paleosols and capped by a till of Laurentide origin. The sections are correlated on the basis of lithology, paleosol development, paleomagnetism, and chlorine dating of surface boulder erratics. A formal stratigraphic nomenclature is proposed for the deposits of this region. The sequence of glacial tills separated by paleosols reflects a long record of glacial–interglacial cycles. Soil properties from the oldest paleosol to modern soil show a general decrease in the degree of soil development, suggesting a progressive deterioration of interglacial climatic conditions. A normal–reverse–normal sequence of remanent magnetization was determined within the stratigraphic succession and assigned to the Gauss–Matuyama–Brunhes chrons, respectively. A Gauss age was assigned to the basal colluvium, an early Matuyama age (including Olduvai) to the first two tills, and a Brunhes age to the last three tills. Laurentide deposits are of Late Wisconsinan age and are restricted to the uppermost part of the stratigraphic succession. Chlorine dates for surface boulders place the all-time limit of the Laurentide Ice Sheet at about 30 ka. The Late Wisconsinan Laurentide Ice Sheet was the only continental ice to reach the Mackenzie and Richardson mountains of the northern Cordillera.

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.

scholarly journals Polyphase Glacigenic Deformation of Advance Glaciofluvial Sediments, Near Big Creek, British Colombia

2007 ◽  
Vol 47 (2) ◽  
pp. 211-219 ◽  
Author(s):  
David H. Huntley ◽  
Bruce E. Broster
Keyword(s):  
British Columbia ◽  
Brittle Failure ◽  
Lateral Extension ◽  
Polyphase Deformation ◽  
Deformation Structures ◽  
Vertical Extension ◽  
British Colombia ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Sheet Deformation

ABSTRACT Deformation structures were observed in glaciofluvial sediments near Big Creek, central British Columbia. These sediments record a sequence of polyphase deformation resulting from the advance and retreat of the Late Wisconsinan (Fraser Glaciation) Cordilleran Ice Sheet. Deformation is attributed to ductile then brittle failure resulting from: (a) horizontal compression and loading as ice advanced over saturated sediments; followed by (b) lateral extension then (c) compression under frozen conditions during glacier overriding; and finally (d) vertical extension during unloading upon déglaciation. Most deformation (a-c, above) appears to have occurred during the advance phase of the Fraser Glaciation.

Time of Maximum Late Wisconsin Glaciation, West Coast of Canada

1990 ◽  
Vol 34 (3) ◽  
pp. 282-295 ◽  
Author(s):  
Bertrand Blaise ◽  
John J. Clague ◽  
Rolf W. Mathewes
Keyword(s):  
West Coast ◽  
North Pacific ◽  
Deep Sea ◽  
North Pacific Ocean ◽  
Ice Sheet ◽  
Late Glacial ◽  
Western Margin ◽  
The Core ◽  
Queen Charlotte Islands ◽  
Cordilleran Ice Sheet

AbstractNew data from a deep-sea core in the eastern North Pacific Ocean indicate that the western margin of the Late Wisconsin Cordilleran Ice Sheet began to retreat from its maximum position after 15,600 yr B.P. Ice-rafted detritus is present in the core below the 15,600 yr B.P. level and was deposited while lobes of the Cordilleran Ice Sheet advanced across the continental shelf in Queen Charlotte Sound, Hecate Strait, and Dixon Entrance. The core data are complemented by stratigraphic evidence and radiocarbon ages from Quaternary exposures bordering Hecate Strait and Dixon Entrance. These indicate that piedmont lobes reached the east and north shores of Graham Island (part of the Queen Charlotte Islands) between about 23,000 and 21,000 yr B.P. Sometime thereafter, but before 15,000–16,000 yr B.P., these glaciers achieved their greatest Late Wisconsin extent. Radiocarbon ages of late-glacial and postglacial sediments from Queen Charlotte Sound, Hecate Strait, and adjacent land areas show that deglaciation began in these areas before 15,000 yr B.P. and that the shelf was completely free of ice by 13,000 yr B.P.

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.

scholarly journals Coeval brittle and ductile deformation beneath the late Wisconsinan Puget Lobe, Washington State, USA

2019 ◽  
Vol 60 (80) ◽  
pp. 100-114
Author(s):  
Jasper Knight
Keyword(s):  
Puget Sound ◽  
Fine Sand ◽  
Washington State ◽  
Ductile Deformation ◽  
Glacial Sediments ◽  
Deformation Structures ◽  
Sediment Stratigraphy ◽  
Close Relationship ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet

AbstractLate Wisconsinan glacial sediments, exposed on Whidbey Island and Camano Island, Puget Sound (Washington State, USA), were deposited in a proglacial shallow marine/outwash environment during northward retreat of the Puget Lobe of the Cordilleran ice sheet. Sediments mainly comprise massive and cross-bedded sand and gravels, and rhythmically-bedded clay and silt/fine sand couplets, interbedded with diamictons that were deposited by a range of mass flows of different viscosities. Although sediment stratigraphy and ice advance–retreat patterns are well established for the Puget Lobe, brittle and ductile deformation structures within, and separating, these sediment units are less well understood. These structures record the nature of ice–bed interactions taking place in subglacial and proglacial environments. This study examines evidence for these processes and environments. Key deformation structures identified include open to overturned folds, normal and reverse faults, clastic dikes and hydrofractures and passive-loading structures. Evidence for coeval development of ductile and brittle deformation structures shows the close relationship between porewater changes, sediment rheology and sediment system responses to changes in strain caused by ice–bed interactions.

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.

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