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

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.

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Quaternary stratigraphy and history, Williams Lake, British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e87-012 ◽

1987 ◽

Vol 24 (1) ◽

pp. 147-158 ◽

Cited By ~ 24

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.

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

Canadian Journal of Earth Sciences ◽

10.1139/e85-079 ◽

1985 ◽

Vol 22 (5) ◽

pp. 748-757 ◽

Cited By ~ 27

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.

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Delaciation of the Prince Rupert – Kitimat area, British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e85-022 ◽

1985 ◽

Vol 22 (2) ◽

pp. 256-265 ◽

Cited By ~ 44

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.

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Quaternary Stratigraphy and History, Quesnel, British Columbia

Géographie physique et Quaternaire ◽

10.7202/032736ar ◽

2007 ◽

Vol 42 (3) ◽

pp. 279-288 ◽

Cited By ~ 13

Author(s):

John J. Clague

Keyword(s):

British Columbia ◽

Late Quaternary ◽

Ice Sheet ◽

Drainage System ◽

Glacial Lakes ◽

Quaternary Stratigraphy ◽

Valley Fills ◽

History Of ◽

Late Wisconsinan ◽

Sand And Gravel

ABSTRACT Thick Quaternary sediments at Quesnel, British Columbia, provide a record of the late Quaternary history of an area near the centre of the former Cordilieran Ice Sheet. These sediments, in part, fill stream valleys that were cut sometime prior to the Late Wisconsinan Fraser Glaciation. Of special note are (1) fluvial or glaciofluvial sand and gravel deposited by aggrading streams, perhaps in part during early Fraser time; (2) thick glaciolacustrine mud, sand, and diamicton laid down later as glaciers advanced across central British Columbia; and (3) glaciolacustrine sediments similar to (2), but deposited in an ice-dammed lake at the end of the Fraser Glaciation. The stratigraphy is punctuated by colluvial deposits that are products of landslides from valley walls at various times during the late Quaternary; this process continues to the present. During the Fraser Glaciation, glaciers from the Coast and Cariboo Mountains coalesced and flowed north over central British Columbia. Fraser Glaciation advance sediments and older Pleistocene deposits were partially removed by this ice sheet and the eroded remnants mantled with till. At the end of this glaciation, the Cordilieran Ice Sheet downwasted and receded southward along an irregular front across the study area. Large amounts of sediment were deposited in glacial lakes dammed by the southward-retreating ice. With complete déglaciation of the interior, glacial lakes drained and the present drainage system was established. At first, valleys were partially aggraded with sand and gravel, but later, streams dissected valley fills to produce a series of terraces at successively lower levels.

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MINERAL DEPOSITS OF THE MIDCONTINENT RIFT SYSTEM - A NEW TIME/SPACE CLASSIFICATION

10.1130/abs/2018am-319225 ◽

2018 ◽

Author(s):

Laurel G. Woodruff ◽

◽

Suzanne W. Nicholson ◽

Connie L. Dicken ◽

Klaus J. Schulz

Keyword(s):

Mineral Deposits ◽

Rift System ◽

Midcontinent Rift ◽

System A ◽

Time Space ◽

Midcontinent Rift System ◽

New Time

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

Canadian Journal of Earth Sciences ◽

10.1139/e88-093 ◽

1988 ◽

Vol 25 (6) ◽

pp. 938-941 ◽

Cited By ~ 20

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.

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A mammoth (Mammuthus primigenius) tooth from late Wisconsin deposits near Embden, North Dakota, and comments on the distribution of woolly mammoths south of the Wisconsin ice sheets

Canadian Journal of Earth Sciences ◽

10.1139/e86-092 ◽

1986 ◽

Vol 23 (7) ◽

pp. 909-918 ◽

Cited By ~ 15

Author(s):

C. R. Harington ◽

Allan C. Ashworth

Keyword(s):

British Columbia ◽

Continental Shelf ◽

North Dakota ◽

Third Molar ◽

Ice Sheets ◽

Lake Agassiz ◽

Mammuthus Primigenius ◽

Sand And Gravel ◽

Woolly Mammoth ◽

Cass County

A well-preserved third molar of a woolly mammoth (Mammuthus primigenius) was recovered from sand and gravel forming the highest (Herman) prominent strandline of Lake Agassiz near Embden in western Cass County, North Dakota. The Herman strandline is estimated to have formed about 11 500 years BP, and presumably the tooth is of similar age. Perhaps the animal lived in a tundra-like area near the Lake Agassiz shoreline.Additional evidence suggests that woolly mammoths occupied a tundra-like range south of the Wisconsin ice sheets extending from southern British Columbia to the Atlantic continental shelf off Virginia.

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Prescribing practices of endocrine therapy for ductal carcinoma in situ in British Columbia

Current Oncology ◽

10.3747/co.25.3795 ◽

2018 ◽

Vol 25 (2) ◽

pp. 133 ◽

Cited By ~ 1

Author(s):

A.T. Chaudhry ◽

T.A. Koulis ◽

C. Speers ◽

R.A. Olson

Keyword(s):

British Columbia ◽

Endocrine Therapy ◽

Ductal Carcinoma In Situ ◽

Carcinoma In Situ ◽

Ductal Carcinoma ◽

Population Based ◽

Cox Regression Analysis ◽

Treatment Centre ◽

Er Status

Purpose The mainstay of treatment for ductal carcinoma in situ (dcis) involves surgery in the form of mastectomy or lumpectomy. Inconsistency in the use of endocrine therapy (et) for dcis is evident worldwide. We sought to assess the variation in et prescribing for patients with dcis across a population-based radiotherapy (rt) program and to identify variables that predict its use.Methods Data from a breast cancer database were obtained for women diagnosed with dcis in British Columbia from 2009 to 2014. Associations between et use and patient characteristics were assessed by chi-square test and multilevel multivariate logistic regression. The Kaplan–Meier method, with propensity score matching and Cox regression analysis, was used to assess the effects of et on overall survival (os) and relapse-free survival (rfs).Results For the 2336 dcis patients included in the study, et use was 13% in dcis patients overall, and 17% in patients with estrogen receptor–positive (er+) tumours treated with breast-conserving surgery and rt. Significant variation in et use by treatment centre was observed (range: 8%–23%; p < 0.001), and prescription of et by individual oncologists varied in the range 0%–40%. After controlling for confounding factors, age less than 50 years [odds ratio (or): 1.72; p = 0.01], treatment centre, er+ status (or: 5.33; p < 0.001), and rt use (or: 1.77; p < 0.001) were significant predictors of et use. No difference in os or rfs with the use of et was observed.Conclusions In this population-based analysis, 13% of patients with dcis in British Columbia received et, with variation by treatment centre (8%–23%) and individual oncologist (0%–40%). Age less than 50 years, er+ status, and rt use were most associated with et use.

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Genesis of carbonate till in the lee sides of Precambrian Shield uplands, Hemlo area, Ontario

Canadian Journal of Earth Sciences ◽

10.1139/e87-191 ◽

1987 ◽

Vol 24 (10) ◽

pp. 2004-2015 ◽

Cited By ~ 5

Author(s):

Stephen R. Hicock

Keyword(s):

Ice Sheet ◽

Glacial Maximum ◽

Laurentide Ice Sheet ◽

The South ◽

Precambrian Shield ◽

Basal Zone ◽

Compressive Flow ◽

Late Wisconsinan ◽

Basal Till

Near Hemlo, Ontario, highly calcareous till is confined to areas located downglacier from Precambrian uplands, at least 150 km from the Paleozoic–Precambrian boundary. It comprises subglacial meltout till between lodgment tills, and the calcareous package overlies noncalcareous basal till (not studied) and underlies noncalcareous supraglacial meltout till. The tills can be distinguished by textural, carbonate, and clast compositions. Glaciotectonic deformations, stone fabrics and striae, and stone provenance from the tills, as well as erosional and depositional landforms, indicate that ice advanced to the south–southwest across bedrock contacts and over Precambrian uplands.Deposition of all five tills can be explained with one glacial event. As the Late Wisconsinan margin of the Laurentide ice sheet advanced against uplands about 20 km northeast of Hemlo it experienced compressive flow while depositing the non calcareous basal till. Upshearing of stoss-side local debris high into the ice also occurred as englacial ice overrode the slowed basal zone. Once over the upland, englacial ice assumed extending flow, and downshearing of distal debris, which was deposited as calcareous lodgment till on the lee sides of uplands. After the glacial maximum, the glacier ceased internal movement and subglacial meltout till was laid down. A late reactivation of the ice deposited the upper lodgment till and final stagnation formed the supraglacial meltout till.

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