scholarly journals Paleoseismic implications of sediment cores from Comox Lake, British Columbia

1993 ◽  
Author(s):  
R H Linden ◽  
J J Clague
Keyword(s):  
British Columbia ◽  
Sediment Cores

A palynological study of postglacial vegetation changes in the University Research Forest, southwestern British Columbia

1973 ◽  
Vol 51 (11) ◽  
pp. 2085-2103 ◽  
Author(s):  
Rolf W. Mathewes
Keyword(s):  
British Columbia ◽  
Pinus Contorta ◽  
Vegetation Change ◽  
Vegetation History ◽  
Sediment Cores ◽  
Silty Clay ◽  
Pollen Diagram ◽  
History Of ◽  
Palynological Study ◽  
The University

The postglacial vegetation history of the University of British Columbia Research Forest was investigated using percentage and absolute pollen analysis, macrofossil analysis, and radiocarbon dating. A marine silty clay deposit records the oldest (12 690 ± 190 years before present (B.P.)) assemblage of terrestrial plant remains so far recovered from the postglacial of south-coastal British Columbia. Lodge-pole pine (Pinus contorta) dominated this early vegetation, although some Abies, Picea, Alnus, and herbs were also present. Sediment cores from two lakes were also studied. The older is Marion Lake, where five pollen assemblage zones are recognized, beginning with a previously undescribed assemblage of Pinus contorta, Salix, and Shepherdia in clay older than 12 350 ± 190 B.P. The pollen diagram from Surprise Lake (11 230 ± 230 B.P.) is divided into three pollen zones which show the same major trends of vegetation change as the Marion Lake diagram.The first report of the postglacial vegetation history of cedar (Thuja and perhaps Chamaecyparis) in southwestern British Columbia is presented from pollen and macrofossil analyses.At about 10 500 B.P. in both lakes, pollen of Douglas fir (Pseudotsuga menziesii) began a rapid increase, probably in response to climatic amelioration. The palynological evidence, supported by well-preserved bryophyte subfossils, suggests that humid coastal conditions have prevailed in the study area since about 10 500 B.P., with virtually no evidence for a classical Hypsithermal interval between 8500 B.P. and 3000 B.P.

Sedimentary Cladoceran remains and their relationship to nutrients and other limnological variables in 53 lakes from British Columbia, Canada

2003 ◽  
Vol 60 (10) ◽  
pp. 1177-1189 ◽  
Author(s):  
Darren G Bos ◽  
Brian F Cumming
Keyword(s):  
British Columbia ◽  
Sediment Cores ◽  
Species Abundance ◽  
Environmental Variable ◽  
Weighted Averaging ◽  
Eutrophic Lakes ◽  
Inference Models ◽  
Cladoceran Remains ◽  
Explanatory Variables ◽  
Averaging Techniques

To develop models to predict past lake-water nutrient levels, the sedimentary remains of Cladocera were sampled from 53 lakes in central British Columbia, Canada. At the same time, the lakes were sampled for a suite of chemical variables. In addition, a host of physical and spatial explanatory variables were collected from each site. Canonical correspondence analysis showed that total phosphorus (TP), which ranged from 5 to 146 µg·L–1, was the measured environmental variable that best described the differences in species composition among the lakes. Additionally, lake depth and surface water temperature were also important in explaining the distribution of cladoceran taxa. Chydorus brevilabris, Daphnia ambigua, Daphnia cf. pulex, and Graptoleberis testudinaria had a preference for eutrophic lakes, whereas Acroperus harpae, Alonella nana, Alonella excisa, Chydorus piger, Daphnia cf. dentifera, and Eubosmina spp. were found in the less productive lakes. Predictive models to estimate TP from species abundance data were developed using weighted averaging techniques. This research has produced strong and significant inference models, which can now be used to reconstruct past changes in lake trophic status from remains of Cladocera in sediment cores.

A regional paleolimnological assessment of the impact of clear-cutting on lakes from the central interior of British Columbia

2001 ◽  
Vol 58 (3) ◽  
pp. 492-505 ◽  
Author(s):  
Kathleen Laird ◽  
Brian Cumming
Keyword(s):  
British Columbia ◽  
Organic Matter ◽  
Species Composition ◽  
Sediment Cores ◽  
Forest Harvesting ◽  
Diatom Species ◽  
Clear Cutting ◽  
Before And After ◽  
The Impact ◽  
Reference Lakes

The impact of forest harvesting on lakes within the central interior of British Columbia was examined in a paleolimnological study of six lakes that had 28–82% of their watersheds clear-cut (impact lakes) and four lakes that had experienced no logging in their watersheds (reference lakes). Changes in diatom species composition and percent organic matter in 210Pb-dated sediment cores were compared over the last 80 years in each of the impact lakes before and after the onset of forest harvesting and, in the reference lakes, before and after 1960 (the average onset of logging in five of the six impact lakes) and before and after 1975 (the onset of logging in one impact lake). Significant changes in species composition of diatoms following forest-harvesting activities were detected in four of the impact lakes and three of the reference lakes; however, the changes in diatom species composition were small, with changes in the relative abundance of the most common species being at most 11%. Significant increases in the percent organic matter after 1960 were found in one impact lake and three reference lakes; again these changes were small, with increases of 2–5%.

Holocene tephras in lake cores from northern British Columbia, Canada

2008 ◽  
Vol 45 (8) ◽  
pp. 935-947 ◽  
Author(s):  
Thomas R. Lakeman ◽  
John J. Clague ◽  
Brian Menounos ◽  
Gerald D. Osborn ◽  
Britta J.L. Jensen ◽  
...  
Keyword(s):  
British Columbia ◽  
Sediment Cores ◽  
Volcanic Field ◽  
Northern Coast ◽  
Lake Area ◽  
Volcanic Province ◽  
Coast Mountains ◽  
White River ◽  
Subalpine Lakes ◽  
Lake Cores

Sediment cores recovered from alpine and subalpine lakes up to 250 km apart in northern British Columbia contain five previously unrecognized tephras. Two black phonolitic tephras, each 5–10 mm thick, occur within 2–4 cm of each other in basal sediments from seven lakes in the Finlay River – Dease Lake area. The upper and lower Finlay tephras are slightly older than 10 220 – 10 560 cal year B.P. and likely originate from two closely spaced eruptions of one or two large volcanoes in the northern Cordilleran volcanic province. The Finlay tephras occur at the transition between deglacial sediments and organic-rich postglacial mud in the lake cores and, therefore, closely delimit the termination of the Fraser Glaciation in northern British Columbia. Sediments in Bob Quinn Lake, which lies on the east edge of the northern Coast Mountains, contain two black tephras that differ in age and composition from the Finlay tephras. The lower Bob Quinn tephra is 3–4 mm thick, basaltic in composition, and is derived from an eruption in the Iskut River volcanic field about 9400 cal years ago. The upper Bob Quinn tephra is 12 mm thick, trachytic in composition, and probably 7000–8000 cal years old. A fifth tephra occurs as a cryptotephra near the top of two cores from the Finlay River area and is correlated to the east lobe of the White River tephra (ca. 1150 cal year B.P.). Although present throughout southern Yukon, the White River tephra has not previously been documented this far south in British Columbia. The tephras are valuable new isochrons for future paleoenvironmental studies in northern British Columbia.

Advance of alpine glaciers during final retreat of the Cordilleran ice sheet in the Finlay River area, northern British Columbia, Canada

2008 ◽  
Vol 69 (2) ◽  
pp. 188-200 ◽  
Author(s):  
Thomas R. Lakeman ◽  
John J. Clague ◽  
Brian Menounos
Keyword(s):  
British Columbia ◽  
Little Ice Age ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Ice Age ◽  
Last Glaciation ◽  
Alpine Glaciers ◽  
Cordilleran Ice Sheet

Sharp-crested moraines, up to 120 m high and 9 km beyond Little Ice Age glacier limits, record a late Pleistocene advance of alpine glaciers in the Finlay River area in northern British Columbia. The moraines are regional in extent and record climatic deterioration near the end of the last glaciation. Several lateral moraines are crosscut by meltwater channels that record downwasting of trunk valley ice of the northern Cordilleran ice sheet. Other lateral moraines merge with ice-stagnation deposits in trunk valleys. These relationships confirm the interaction of advancing alpine glaciers with the regionally decaying Cordilleran ice sheet and verify a late-glacial age for the moraines. Sediment cores were collected from eight lakes dammed by the moraines. Two tephras occur in basal sediments of five lakes, demonstrating that the moraines are the same age. Plant macrofossils from sediment cores provide a minimum limiting age of 10,550–10,250 cal yr BP (9230±5014C yr BP) for abandonment of the moraines. The advance that left the moraines may date to the Younger Dryas period. The Finlay moraines demonstrate that the timing and style of regional deglaciation was important in determining the magnitude of late-glacial glacier advances.

scholarly journals Radiotracer Estimation of Microbial Biomass in Lake Sediment

1985 ◽  
Vol 42 (2) ◽  
pp. 373-379
Author(s):  
Gerald G. Marten
Keyword(s):  
British Columbia ◽  
Microbial Biomass ◽  
Lake Sediment ◽  
Sediment Cores ◽  
Total Biomass ◽  
Biomass Of Microorganisms

The biomass of sediment organisms can be measured by allowing carbon tracer to distribute itself through sediment cores. Application of this method to sediment from Marion Lake, British Columbia, indicated that most of the sediment microorganisms were concentrated in the top 2 cm of sediment, where the total biomass of microorganisms was estimated to be 183 μg C/cm2. The radiotracer estimate compared favorably with independent measurements based on ATP and direct microscopic counts of sediment microorganisms.

Deglacial landforms and Holocene vegetation trajectories in the northern interior cedar-hemlock forests of British Columbia

2020 ◽  
Author(s):  
Daniel Girard Gavin ◽  
Ariana White ◽  
Paul Sanborn ◽  
Richard Hebda
Keyword(s):  
British Columbia ◽  
Fire History ◽  
Vegetation History ◽  
Sediment Cores ◽  
Rocky Mountain ◽  
Tsuga Heterophylla ◽  
Thuja Plicata ◽  
Radiocarbon Dates ◽  
Lower Terrace ◽  
Closed Canopy

The northern Rocky Mountain Trench of eastern British Columbia is a broad valley mantled by glaciolacustrine terraces supporting a complex mix of mesic-temperate (“interior wetbelt”) forests that are strongly affected by terrain and substrate. Neither the geomorphic history during early-Holocene deglaciation nor the vegetation history of the origin of the Tsuga heterophylla and Thuja plicata populations in the interior wetbelt forest is well understood. Sediment cores were obtained from two lakes, 10 km apart and occupying different terraces (83 m elevational difference) and compared to existing fire-history and paleoclimate reconstructions. Radiocarbon dates and a mapped terrain classification indicate the upper terrace formed as a lacustrine and glaciofluvial kame terrace hundreds of years prior to a lower terrace formed by glaciolacustrine sediments of a proglacial lake. The minimum limiting ages of these terraces correlate with dated jökulhlaup deposits of the Fraser River. The upper site’s first detectable pollen at > 11.0 ka was dominated by light-seeded pioneer taxa (Poaceae, Artemisia, and Populus) followed by a peak in Pinus and finally dominance by Betula at 10.2 ka. Pollen data suggest an earlier invasion of T. heterophylla than previously understood. Wetlands on extensive poorly drained glaciolacustrine soils promoted the persistence of boreal taxa and open forests (e.g., Picea mariana) while the better-drained upper kame terrace promoted development of closed-canopy shade-tolerant taxa. Invasion and expansion of mesic cedar-hemlock taxa progressed since at least the middle Holocene but was highly constrained by edaphic controls.

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