Rock avalanches at Texas Creek, British Columbia

1990 ◽  
Vol 27 (10) ◽  
pp. 1316-1329 ◽  
Author(s):  
J. M. Ryder ◽  
M. J. Bovis ◽  
M. Church
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Landslide Dam ◽  
Steep Slope ◽  
Alluvial Fan ◽  
Fraser River ◽  
Geological Evidence ◽  
Sudden Failure ◽  
Rock Avalanches ◽  
A Site

At least two rock avalanches have occurred during Holocene time at the confluence of Texas Creek and Fraser River, about 300 km upstream from Vancouver. The morphological features of the avalanche debris are well preserved, and its stratigraphic relations are well exposed. Failures occurred in fractured argillites adjacent to a small pluton at a site where a steep slope is maintained as a result of undercutting by Fraser River. The first and largest (45 × 106 m3) avalanche occurred during middle to late Holocene time. Debris infilled the postglacial gorges of the streams and spread across a partly dissected alluvial fan. An anomalous ridge on the avalanche deposit reflects the influence of a buried scarp on debris motion and failure in underlying Pleistocene silts. A sharp contact between debris of differing lithologies suggests that the avalanche moved as a coherent mass. A second, smaller (about 7.2 × 106 m3) avalanche occurred about 120014C years ago.Archaeological and geological evidence from sites upstream suggests that the second avalanche impounded Fraser River, causing backwater sedimentation at Lillooet and blocking the migration of salmon. Another avalanche could occur at this site, with similar effects; sudden failure of the landslide dam could generate a catastrophic flood downstream.

Postglacial spread of hemlock (Tsuga) and vegetation history in Mount Revelstoke National Park, British Columbia, Canada

2003 ◽  
Vol 81 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Sandra M Rosenberg ◽  
Ian R Walker ◽  
Rolf W Mathewes
Keyword(s):  
British Columbia ◽  
National Park ◽  
Late Holocene ◽  
Environmental Changes ◽  
Vegetation History ◽  
Climatic Conditions ◽  
Western Hemlock ◽  
Migration Route ◽  
Geological Evidence ◽  
Eagle Lake

To investigate postglacial environmental changes in southeastern British Columbia, subfossil pollen was analyzed from Eagle Lake, Mount Revelstoke National Park. Palynological evidence suggests that during the early Holocene, Eagle Lake was surrounded by an open forest. The pollen assemblage indicates that climatic conditions were warmer and drier than at present with high alder pollen values. Spruce and fir were common in local forests throughout the Holocene. Western hemlock pollen first occurs at approximately 3500 14C years BP. The migration path of western hemlock into this region is currently unclear. Data from palynological records appear insufficient to resolve the migration pattern, although several routes are possible. The available data support northward migration into southeastern British Columbia. The arrival of this conifer may be in response to the late Holocene increase in precipitation, as inferred from many lower elevation and coastal sites. Mountain hemlock pollen does not appear until about 2100 14C years BP. Mountain hemlock's migration route into southeastern British Columbia is also unresolved. In the late Holocene, the presence of mountain hemlock, and increases of Ericales and Valeriana sitchensis pollen, suggest a shift to the more open, cool, and moist conditions characteristic of the modern-day subalpine parkland. These climatic inferences correspond closely to those derived from other palynological and geological evidence throughout southern British Columbia.Key words: pollen, vegetation, Tsuga, hemlock, British Columbia, Holocene, climate.

Migration of viscous non-aqueous phase liquids (NAPLs) in alluvium, Fraser River lowlands, British Columbia

2006 ◽  
Vol 43 (7) ◽  
pp. 694-703 ◽  
Author(s):  
Richard E Jackson ◽  
Varadarajan Dwarakanath ◽  
John E Ewing ◽  
John Avis
Keyword(s):  
British Columbia ◽  
Aqueous Phase ◽  
Coal Tar ◽  
Chlorinated Solvents ◽  
Creeping Flow ◽  
Fraser River ◽  
Manufactured Gas Plants ◽  
A Site ◽  
Gas Plants

Coal tar, creosote, and similar viscous non-aqueous phase liquids (NAPLs) behave in alluvial soils in a manner significantly different from that of less viscous NAPLs, such as gasoline and chlorinated solvents. Their unique behavior is due to the interaction of their physical–chemical parameters: a density often greater than water, a viscosity significantly greater than water, and an interfacial tension that yields a positive initial spreading coefficient at air–water–NAPL interfaces. This results in slow, creeping flow that causes long-term contamination at former manufactured gas plants and wood-preserving sites and of their adjacent surface waters. Multiphase simulations of this creeping flow are shown for a site along the lower Fraser River near Vancouver, British Columbia, and the long-term consequences of the migration of viscous NAPLs in alluvium are discussed from the perspective of site characterization and brownfields redevelopment.Key words: creosote, coal tar, multiphase simulation, brownfields, NAPL.

Bedforms, bed material, and bedload transport in a salt-wedge estuary: Fraser River, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1440-1452 ◽  
Author(s):  
R. A. Kostaschuk ◽  
M. A. Church ◽  
J. L. Luternauer
Keyword(s):  
British Columbia ◽  
River Discharge ◽  
Bedload Transport ◽  
Fraser River ◽  
Seasonal Fluctuations ◽  
Salt Wedge ◽  
Migration Rates ◽  
Material Load ◽  
Bed Material

The lower main channel of the Fraser River, British Columbia, is a sand-bed, salt-wedge estuary in which variations in velocity, discharge, and bedform characteristics are contolled by river discharge and the tides. Bed-material composition remains consistent over the discharge season and in the long term. Changes in bedform height and length follow but lag behind seasonal fluctuations in river discharge. Migration rates of bedforms respond more directly to river discharge and tidal fall than do height and length. Bedform characteristics were utilized to estimate bedload transport in the estuary, and a strong, direct, but very sensitive relationship was found between bed load and river discharge. Annual bedload transport in the estuary is estimated to be of the order of 0.35 Mt in 1986. Bedload transport in the estuary appears to be higher than in reaches upstream, possibly because of an increase in sediment movement along the bed to compensate for a reduction in suspended bed-material load produced by tidal slack water and the salt wedge.

Identification and significance of late Holocene tephra from Otter Creek, southern British Columbia, and localities in west-central Alberta

1977 ◽  
Vol 14 (11) ◽  
pp. 2593-2600 ◽  
Author(s):  
J. A. Westgate
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Far North ◽  
West Central ◽  
Tephra Beds ◽  
Middle Unit ◽  
Mount St Helens

Three thin, light-coloured, ash-grade tephra beds occur within the uppermost metre of peat at Otter Creek bog in southern British Columbia. The youngest tephra is related to the ~2600 year old Bridge River tephra but is probably the product of a younger and weaker eruption that directed tephra to the southeast of the vent, believed to be located in the Meager Mountain district of southwestern British Columbia. The middle unit is ~2100 years old and is tentatively correlated with one of the upper beds of set P tephra of Mount St. Helens in Washington. The lowermost tephra is equivalent to the Yn bed of set Y, derived from an eruption of Mount St. Helens about 3400 years ago.The Yn tephra has been located as far north as Entwistle in west-central Alberta but mineralogically and chemically similar tephra elsewhere in this region is ~4300 years old and thus represents an older part of the Y set. Significant compositional differences between these two extensive members of the Y set have not yet been recognized.

Breeding characteristics of Townsend's vole (Microtus townsendii) during population fluctuations

1980 ◽  
Vol 58 (4) ◽  
pp. 623-625 ◽  
Author(s):  
Terry D. Beacham
Keyword(s):  
British Columbia ◽  
Sexual Maturity ◽  
Fraser River ◽  
Population Fluctuations ◽  
Peak Density ◽  
Decline Phase ◽  
Early Maturing ◽  
Fraser River Delta ◽  
Peak Phase ◽  
Microtus Townsendii

A 2-year livetrapping study on Townsend's vole (Microtus townsendii) on Reifel Island in the Fraser River delta in British Columbia, Canada, showed that there was an early stop to summer breeding in the peak phase summer compared with the increasing phase summer. Selective dispersal and death of early-maturing voles may account for this result. A delay occurred in the onset of breeding in the decline phase. Voles in peak density populations had the highest median weights at sexual maturity, and males matured at heavier weights than did females.

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