Delaciation of the Prince Rupert – Kitimat area, British Columbia

1985 ◽  
Vol 22 (2) ◽  
pp. 256-265 ◽  
Author(s):  
John J. Clague
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Marine Environment ◽  
Marine Molluscs ◽  
Tidewater Glaciers ◽  
Isostatic Uplift ◽  
Late Wisconsinan ◽  
Cordilleran Ice Sheet ◽  
Sand And Gravel ◽  
Outer Coast

Late Wisconsinan sediments in the Prince Rupert – Kitimat area of west-central British Columbia were deposited in an isostatically depressed marine environment affected by grounded tidewater glaciers. The most common sediments are (1) massive, bedded, and laminated muds, and (2) stratified sand and gravel. The former are accumulations of clay- and silt-size detritus transported in suspension from the mouths of meltwater streams and possibly in turbidity flows generated by submarine slope failures. The muds locally contain scattered ice-rafted stones, fossil marine molluscs, and foraminifera. The main sand and gravel deposits are elevated deltas, including both small incised fan-shaped forms at the margins of the main valleys and enormous ice-contact delta–sandur complexes on the floor of Kitsumkalum–Kitimat trough, the largest valley in the study area.Delaciation occurred by downwasting and complex frontal retreat between about 13 000 and 10 000 BP. The open outer coast became ice free first, in response to wholesale destabilization of the western periphery of the Cordilleran ice sheet by eustatically rising seas. Glaciers retreated rapidly by calving and soon were confined to fjords and mountain valleys; thereafter, they receded more slowly. The distribution of glaciomarine mud and raised deltaic deposits in Kitsumkalum–Kitimat trough indicates that retreat there was nonuniform, with intervals of catastrophic retreat separated by periods during which glacier snouts were relatively stable.Delaciation was accompanied and followed by rapid isostatic uplift. In Kitsumkalum–Kitimat trough, shorelines fell from about 200 m elevation at 10 500 BP to present sea level at about 8000 BP; about half of this fall occurred in perhaps as little as 500 years.

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.

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.

The Sisters Creek Formation: Pleistocene sediments representing a nonglacial interval in southwestern British Columbia at about 18 ka

1995 ◽  
Vol 32 (6) ◽  
pp. 758-767 ◽  
Author(s):  
Stephen R. Hicock ◽  
Olav B. Lian
Keyword(s):  
British Columbia ◽  
Glacial Maximum ◽  
Time Space ◽  
Late Wisconsinan ◽  
Sand And Gravel ◽  
New Time

Sisters Creek Formation is formally defined, stratotypes are established for it, and the time–space chart is updated for the Fraser Lowland, southwestern British Columbia. The Sisters Creek is a Pleistocene formation comprising in situ and reworked organic-rich sediments, and nonorganic silt, sand, and gravel. The formation was deposited during the Port Moody interstade (within the Late Wisconsinan Fraser Glaciation; δ18O stage 2) between the Coquitlam stade (early Fraser Glaciation) and the main Vashon stadial maximum that occurred about 14.5 ka. The Sisters Creek Formation represents a glacial recession in southwestern British Columbia that generally coincided with the timing of the last global glacial maximum. The new time–space chart implies that, in Fraser Lowland, the Fraser Glaciation represents the rapid advances and retreats of glacial lobes issuing from surrounding mountains, which remained ice-covered during interstades.

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.

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 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.

Substrates of the Strait of Georgia, British Columbia

1983 ◽  
Vol 40 (7) ◽  
pp. 1026-1032 ◽  
Author(s):  
J. L. Luternauer ◽  
J. J. Clague ◽  
C. H. Pharo
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Intertidal Zone ◽  
Fraser River ◽  
Pleistocene Glaciation ◽  
Delta Front ◽  
Strait Of Georgia ◽  
Local Wave ◽  
Fraser River Delta ◽  
Sand And Gravel

The subtidal floor of the Strait of Georgia west of the Fraser River Delta and north to Texada Island is blanketed mainly by silt and clay derived from the Fraser River and from failed deposits at the delta front. On the western part of the Strait south of the delta to the San Juan and Orcas islands, sediments are mainly lag sand and gravel eroded from Pleistocene deposits by strong tidal currents. East of this area in a more sheltered embayed part of the Strait the seafloor is covered by silt and clay derived from local mainland streams and possibly from the Fraser River. North of southern Texada Island, influence of the Fraser River also has been minimal. Although bottoms of basins in this part of the Strait are blanketed by mud, coarser sediments are dominant elsewhere. Substrate materials in the northern Strait are products of wave and current reworking of Pleistocene deposits and deposition from local streams and rivers. The shoreline of the Strait is mainly rocky but includes sand and/or gravel beaches and deltaic tidal flats. Development of the intertidal zone has been controlled by Pleistocene glaciation, postglacial changes in sea level, local wave and current regimes, and sediment availability.

Seismic reflection investigation of Kalamalka Lake: a "fiord lake" on the Interior Plateau of southern British Columbia

1990 ◽  
Vol 27 (9) ◽  
pp. 1225-1235 ◽  
Author(s):  
Henry T. Mullins ◽  
Nicholas Eyles ◽  
Edward J. Hinchey
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Seismic Reflection ◽  
Lake Basin ◽  
Seismic Reflection Profile ◽  
Sediment Record ◽  
History Of ◽  
Cordilleran Ice Sheet ◽  
Continental Interior ◽  
Sediment Fill

A uniboom seismic reflection profile survey has revealed the nature of bedrock relief and the acoustic character of Pleistocene glacial sediment fill beneath Kalamalka Lake in southern British Columbia. Despite its continental interior setting, Kalamalka Lake basin has many attributes of coastal fiords, such as being overdeepened below sea level and having closed bedrock depressions and a thick sediment fill.The bedrock surface beneath Kalamalka Lake has been eroded as much as 417 m below lake level (26 m below sea level) and is characterized by a series of closed, glacially overdeepened depressions. We suggest that the location of the lake basin is structurally controlled but was overdeepened by rapidly flowing ice that drained the interior portions of the Cordilleran ice sheet during repeated Pleistocene glaciations.Up to 272 m of sediment has been deposited beneath Kalamalka Lake. The greatest thickness of the sediment fill (up to 237 m) is a seismically transparent unit that overlies a thin (up to 20 m), discontinuous lower stratified unit and is overlain by a thin (up to 15 m), continuous upper unit that is well stratified. The sedimentological nature of the lower stratified unit is not known but could represent a discontinuous coarse lag. The thick, middle transparent unit is interpreted as a massive silt deposited rapidly in a proglacial lake from suspended-sediment plumes during deglaciation. The thin overlying stratified unit may be correlative with laminated glaciolacustrine "white silt" deposits that outcrop extensively across central and southern British Columbia, suggesting a common history of deglaciation and sedimentation.An ambitious research program focused on seismic stratigraphic definition, coupled with direct drill-core sampling, is needed to take full advantage of the extensive sediment record that exists beneath the large, glacially overdeepened lakes of southern British Columbia.

Early growth of the last Cordilleran ice sheet deduced from glacio-isostatic depression in southwest British Columbia, Canada

2005 ◽  
Vol 63 (1) ◽  
pp. 53-59 ◽  
Author(s):  
John J. Clague ◽  
Duane Froese ◽  
Ian Hutchinson ◽  
Thomas S. James ◽  
Karen M. Simon
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Initial Phase ◽  
Ice Sheet ◽  
Early Growth ◽  
Relative Sea Level ◽  
Strait Of Georgia ◽  
The Difference ◽  
Cordilleran Ice Sheet

Relative sea level at Vancouver, British Columbia rose from below the present datum about 30,000 cal yr B.P. to at least 18 m above sea level 28,000 cal yr B.P. In contrast, eustatic sea level in this interval was at least 85 m lower than at present. The difference in the local and eustatic sea-level positions is attributed to glacio-isostatic depression of the crust in the expanding forefield of the Cordilleran ice sheet during the initial phase of the Fraser Glaciation. Our findings suggest that about 1 km of ice was present in the northern Strait of Georgia 28,000 cal yr B.P., early during the Fraser Glaciation.

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