Late Pleistocene history and geomorphology, southwestern Vancouver Island, British Columbia

1979 ◽  
Vol 16 (9) ◽  
pp. 1645-1657 ◽  
Author(s):  
Neville F. Alley ◽  
Steven C. Chatwin
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Late Pleistocene ◽  
Vancouver Island ◽  
Glacial Lakes ◽  
Small Lakes ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

The major Pleistocene deposits and landforms on southwestern Vancouver Island are the result of the Late Wisconsin (Fraser) Glaciation. Cordilleran glaciers formed in the Vancouver Island Mountains and in the Coast Mountains had advanced down Strait of Georgia to southeastern Vancouver Island after 19 000 years BP. The ice split into the Puget and Juan de Fuca lobes, the latter damming small lakes along the southwestern coastal slope of the island. During the maximum of the glaciation (Vashon Stade), southern Vancouver Island lay completely under the cover of an ice-sheet which flowed in a south-southwesterly direction across Juan de Fuca Strait, eventually terminating on the edge of the continental shelf. Deglaciation was by downwasting during which ice thinned into major valleys and the strait. Most upland areas were free of ice down to an elevation of 400 m by before 13 000 years BP. A possible glacier standstill and (or) resurgence occurred along Juan de Fuca Strait and in some interior upland valleys before deglaciation was complete. Glacial lakes occupied major valleys during later stages of deglaciation.

Four Pleistocene formations in southwest British Columbia: their implications for patterns of sedimentation of possible Sangamonian to early Wisconsinan age

1983 ◽  
Vol 20 (8) ◽  
pp. 1232-1247 ◽  
Author(s):  
Stephen R. Hicock ◽  
John E. Armstrong
Keyword(s):  
Stream Flow ◽  
Vancouver Island ◽  
Tsuga Heterophylla ◽  
Last Interglacial ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Arboreal Pollen ◽  
Juan De Fuca ◽  
Stratigraphic Position ◽  
Juan De Fuca Strait

Semiahmoo and Dashwood drifts were deposited during the penultimate glaciation, and Highbury Sediments and Muir Point Formation during the last interglacial. These sediments are defined and described, and stratotypes are established for them.Based on arboreal pollen assemblages, lithologic similarity, and relative stratigraphic position, Semiahmoo Drift of the Fraser Lowland is tentatively correlated with Dashwood Drift of Vancouver Island. Stone provenance, till fabrics, glaciotectonic structures, cross-bedding, and stone imbrication indicate that regional ice and meltwater flowed out of major fiords in the Coast Mountains and into the ancestral Strait of Georgia during the penultimate glaciation. Ice flowed southeastward against the east coast of Vancouver Island, and down the axis of the strait. Pollen and molluscs in Semiahmoo and Dashwood fossiliferous muds give evidence of transition from glaciomarine to marine conditions at the close of the penultimate glaciation.Highbury Sediments of the Fraser Lowland perhaps correlate with the Muir Point Formation of Vancouver Island, based on lithologic similarity and relative stratigraphic position. Stone provenance and paleocurrent data indicate that stream flow during the last interglacial issued from nearby mountains and onto coastal floodplains that shelved into the ancestral Strait of Georgia and Juan de Fuca Strait. Abundant Pseudotsuga and Tsuga heterophylla pollen indicate that climate during that time was at least as warm as the present.

Late Pleistocene stratigraphy and chronology of lower Chehalis River valley, southwestern British Columbia: evidence for a restricted Coquitlam Stade

2004 ◽  
Vol 41 (7) ◽  
pp. 881-895 ◽  
Author(s):  
Brent C Ward ◽  
Bruce Thomson
Keyword(s):  
British Columbia ◽  
Late Pleistocene ◽  
River Valley ◽  
Glacial Lakes ◽  
Coast Mountains ◽  
Source Areas ◽  
Definitive Evidence

Sediments in lower Chehalis valley span middle Wisconsin (Olympia nonglacial interval) to Holocene time. Sediments are divided into six units with chronological control provided by 14 new radiocarbon ages. Fluvial gravel spans the transition from the late Olympia nonglacial interval to the early Fraser Glaciation. Glaciolacustrine sedimentation represents the first definitive glacial activity in the valley and indicates that Vashon ice in the Fraser Lowland blocked the mouth of the Chehalis valley at ca. 18–17 ka BP. Ice then flowed down the Chehalis valley. The Chehalis valley deglaciated while ice persisted in the Fraser Lowland, forming another lake. After this lake drained, terraces and fans formed. This style of glaciation–deglaciation is typical of many watersheds peripheral to the Fraser Lowland in that local valley ice was slightly out of phase with ice in the lowland. This resulted in glacial lakes forming during both advance and retreat phases. However, in contrast to watersheds in the northwestern Fraser Lowland, no definitive evidence of a Coquitlam ice advance was found within the Chehalis valley. Although glaciers in the area were likely active and advancing, data from the Chehalis valley indicates that they were not as extensive as previously thought. Since ice source areas in the northeastern Fraser Lowland are in the leeward area of the Coast Mountains, it is suggested that lower precipitation resulted in limited glacier activity there during the Coquitlam Stade.

Quadra Sand and its relation to the late Wisconsin glaciation of southwest British Columbia

1976 ◽  
Vol 13 (6) ◽  
pp. 803-815 ◽  
Author(s):  
J. J. Clague
Keyword(s):  
British Columbia ◽  
Climatic Change ◽  
Late Pleistocene ◽  
Marine Sediments ◽  
Strait Of Georgia ◽  
Coast Mountains ◽  
Widespread Distribution ◽  
Source Areas ◽  
The North ◽  
Minimum Age

Quadra Sand is a late Pleistocene lithostratigraphic unit with widespread distribution in the Georgia Depression, British Columbia and Puget Lowland, Washington. The unit consists mainly of horizontally and cross-stratified, well sorted sand. It is overlain by till deposited during the Fraser Glaciation and is underlain by fluvial and marine sediments deposited during the preceding nonglacial interval.Quadra Sand was deposited progressively down the axis of the Georgia–Puget Lowland from source areas in the Coast Mountains to the north and northeast. The unit is markedly diachronous; it is older than 29 000 radiocarbon years at the north end of the Strait of Georgia, but is younger than 15 000 years at the south end of Puget Sound.Aggradation of the unit occurred during the climatic deterioration at the beginning of the Fraser Glaciation. Thick, well sorted sand was deposited in part as distal outwash aprons at successive positions in front of, and perhaps along the margins of, glaciers advancing from the Coast Mountains into the Georgia–Puget Lowland during late Wisconsin time.The sand thus provides a minimum age for the initial climatic change accompanying the Fraser Glaciation. This change apparently occurred before 28 800 y BP, substantially earlier than glacial occupation of the southern Interior Plateau of British Columbia. Thus, several thousand years may have intervened between the alpine and ice-sheet phases of the Fraser Glaciation.

Stygobromus quatsinensis, a new amphipod crustacean (Crangonyctidae) from caves on Vancouver Island, British Columbia, with remarks on zoogeographic relationships

1987 ◽  
Vol 65 (9) ◽  
pp. 2202-2209 ◽  
Author(s):  
John R. Holsinger ◽  
D. Patrick Shaw
Keyword(s):  
British Columbia ◽  
Vancouver Island ◽  
Western United States ◽  
Pleistocene Glaciation ◽  
Juan De Fuca ◽  
Alternative Hypotheses ◽  
Amphipod Crustacean ◽  
Coarse Sediments ◽  
Juan De Fuca Strait ◽  
A New Species

Stygobromus quatsinensis, a new species of subterranean, freshwater amphipod crustacean, is described from caves on Vancouver Island, British Columbia, Canada. This is the 3rd stygobiont amphipod recorded from Canada and the 11th member of the genus Stygobromus to be found in localities north of the southern limits of Pleistocene glaciation. Stygobromus quatsinensis is a member of the hubbsi group, an assemblage of closely similar stygobiont species previously recorded from the central and western United States south of British Columbia. Two alternative hypotheses are proposed to explain the presence of S. quatsinensis on a glaciated island separated from the mainland by marine straits. One theory suggests that it evolved from putative ancestors that were present on the island before development of the Juan de Fuca Strait in the Eocene. The other suggests that it gained access to the island from the mainland through interstitial routes in coarse sediments of the Quadra Sand which infilled parts of the Georgia Strait in the late Pleistocene. Both theories assume that this species has survived glaciation in subglacial groundwater refugia.

Factors influencing the distribution of Egregia menziesii (Phaeophyta, Laminariales) in British Columbia, Canada

1978 ◽  
Vol 56 (9) ◽  
pp. 1198-1205 ◽  
Author(s):  
D. K. Gordon ◽  
R. E. DE Wreede
Keyword(s):  
British Columbia ◽  
High Temperature ◽  
Laboratory Experiments ◽  
Algal Flora ◽  
The West ◽  
Common Component ◽  
Strait Of Georgia ◽  
Low Salinity ◽  
Factors Influencing ◽  
Juan De Fuca

Egregia menziesii (Turner) Areschoug is a common component of the algal flora along the west coast of Vancouver Island, Queen Charlotte Strait, and the Strait of Juan de Fuca but is absent from the Strait of Georgia in British Columbia, Canada. This distribution pattern was found to be correlated with temperature and salinity in that E. menziesii is not present in areas where there are seasonal periods of low salinity and high temperature. To test this correlation, field transplants of sporophytes and laboratory experiments with sporophytes and culture work were carried out. The results suggest that the distribution of E. menziesii is limited by specific combinations of salinity and temperature; it requires high salinities and temperatures less than 15 °C for its survival.

Seiche Excitation in Port San Juan, British Columbia

1979 ◽  
Vol 36 (10) ◽  
pp. 1223-1227
Author(s):  
D. D. Lemon ◽  
P. H. LeBlond ◽  
T. R. Osborn
Keyword(s):  
British Columbia ◽  
Water Waves ◽  
Pressure Gauge ◽  
Low Frequency ◽  
San Juan ◽  
External Forcing ◽  
Edge Waves ◽  
Rectangular Basin ◽  
Juan De Fuca ◽  
Juan De Fuca Strait

Seiche motions observed in San Juan Harbour with a bottom-mounted pressure gauge have been Fourier-analyzed and interpreted in terms of a theoretical model of oscillations in a rectangular basin with an exponential depth profile. Two of the observed periods (at 14.6 and 38.5 min) are identified with resonances of the basin; two other significant low frequency peaks (at 21 and 55 min) do not coincide with resonant periods of the basin and must be due to strong external forcing. Higher frequency fluctuations (20–160 s) are attributed to swell and to its subharmonic interactions with edge waves. Key words: water waves, seiches, mathematical model, Juan de Fuca Strait, British Columbia

Sign in / Sign up

Export Citation Format

Share Document