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 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.

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.

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.

scholarly journals Estimates of Chinook salmon consumption in Washington State inland waters by four marine mammal predators from 1970 to 2015

2017 ◽  
Vol 74 (8) ◽  
pp. 1173-1194 ◽  
Author(s):  
Brandon Chasco ◽  
Isaac C. Kaplan ◽  
Austen Thomas ◽  
Alejandro Acevedo-Gutiérrez ◽  
Dawn Noren ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Marine Mammal ◽  
Oncorhynchus Tshawytscha ◽  
Interspecific Interactions ◽  
Puget Sound ◽  
The United States ◽  
Washington State ◽  
Killer Whales ◽  
Protected Species ◽  
Annual Biomass

Conflicts can arise when the recovery of one protected species limits the recovery of another through competition or predation. The recovery of many marine mammal populations on the west coast of the United States has been viewed as a success; however, within Puget Sound in Washington State, the increased abundance of three protected pinniped species may be adversely affecting the recovery of threatened Chinook salmon (Oncorhynchus tshawytscha) and endangered killer whales (Orcinus orca) within the region. Between 1970 and 2015, we estimate that the annual biomass of Chinook salmon consumed by pinnipeds has increased from 68 to 625 metric tons. Converting juvenile Chinook salmon into adult equivalents, we found that by 2015, pinnipeds consumed double that of resident killer whales and six times greater than the combined commercial and recreational catches. We demonstrate the importance of interspecific interactions when evaluating species recovery. As more protected species respond positively to recovery efforts, managers should attempt to evaluate tradeoffs between these recovery efforts and the unintended ecosystem consequences of predation and competition on other protected species.

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.

From “Superabundance” to Dependency

2017 ◽  
Author(s):  
Chris Friday
Keyword(s):  
Puget Sound ◽  
Fur Trade ◽  
Potato Production ◽  
Washington State ◽  
European American ◽  
Cultivation Practices ◽  
Settler Society ◽  
Indian Agents

Agricultural cultivation was an integral cultural and economic feature of Indian peoples' lives in the greater Puget Sound. Exactly when potatoes became deeply embedded in these cultivation practices is unclear, but by the late 1820s they were common fare throughout the region. With the onset of the inland fur trade in the 1820s and the establishment of a European American settler society (circa 1850s), potato production expanded. This chapter shows that Lummi women in northwest Washington state were the primary cultivators of potato agriculture and yet their roles in such production was effectively eclipsed as the heteronormative determinations of Indian agents characterized potato cultivation as exclusively masculine.

First Report of Downy Mildew of Chives Caused by Peronospora destructor in the Pacific Northwest

2003 ◽  
Vol 4 (1) ◽  
pp. 38
Author(s):  
Dean A. Glawe
Keyword(s):  
Downy Mildew ◽  
Pacific Northwest ◽  
Puget Sound ◽  
Washington State ◽  
King County ◽  
Specialty Crops ◽  
First Report ◽  
Peronospora Destructor ◽  
The Pacific ◽  
Allium Schoenoprasum

Chive (Allium schoenoprasum L.) is one of the specialty crops grown by farmers in the Puget Sound region of Washington State. In September, 2002, downy mildew symptoms were observed in a 0.2 hectare field planting of chive near Fall City, King County, WA. Downy mildew had not been reported previously on chive in the Pacific Northwest. Accepted for publication 15 April 2003. Published 12 May 2003.

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