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Postglacial chronology of large earthflows in south-central British ColumbiaJones, Penelope Sarah Ann January 1988 (has links)
Fifty-three earthflows in south-central British Columbia were identified
from an air photograph search and from a review of previous geologic reports. Many have parallel 'en echelon1 lateral deposits indicative of several
movement phases during the postglacial period, and some have been active
during the present century up to the time of the study. The purpose of this study was to date phases of earthflow activity during the postglacial period and relate them to climatic fluctuations.
Earthflows in the study area are concentrated in serpentinised peridotite, basalt, sediments (mainly volcaniclastics), and other volcanics. Earthflows take place preferentially down dip in sediments and many are associated
with fault lines. All earthflow materials, except those derived from serpentinised peridotite, weather to montmorillonite-rich material, and each yields a characteristic grain-size distribution. Earthflow gradient in the study area depends upon material type, indicating that earthflow texture and mineralogy govern shearing resistance and hence partially determine characteristic
slope angles.
Earthflow movement during the past 60 years was investigated using air photograph chronosequences dating back to 1928. Reactivations of six flows were identified in the period 1950 to 1960, and an analysis of precipitation records from four stations around the study area showed that the level of winter precipitation increased around 1950. It was concluded that the observed
reactivation was a response to rising groundwater levels during a period of increased winter precipitation.
Earthflow movement and climatic fluctuations over the last 200 years were investigated in an analysis of tree-ring width records at four sites. Moist phases were recorded in the periods 1800-1830, 1870-1920 and from 1945 to the present. Compression wood formation at three sites corresponded with moist phases, so it was concluded that, over the last two centuries, earthflow movement was probably coincident with phases of higher precipitation.
A postglacial climatic chronology was inferred from published pollen analyses and from Neoglacial ice fluctuations, both within and outside the study area. New palynological data were collected from Red Mountain, a high elevation site in the west of the study area. These showed a two-phase cooling period following the close of the Hypsithermal. The first cooling period took place around 6-7,000 BP, and the second around 3,000 BP.
Earthflow movement during the postglacial period was analysed using radiocarbon dates, tephrochronology, stratigraphy, carbonate accumulation, and earthflow morphology. Data from twenty-one sites showed that movement was concentrated mainly after 7,000 BP, and at several sites the stratigraphic position of the Bridge River tephra dated movement around 2,400 BP. It was concluded that, at this longer timescale, movement at many sites could be attributed to post-Hypsithermal climatic deterioration. / Arts, Faculty of / Geography, Department of / Graduate
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Late Holocene climate and glacier fluctuations in the Cambria Icefield area, British Columbia Coast Mountains.Johnson, Kate 02 June 2011 (has links)
In the British Columbia Coast Mountains most dendroclimatological and dendroglaciological studies have focused on developing insights from tree‐ring sites located in the southern and central regions. By contrast relatively few studies have been conducted in the northwestern Coast Mountains, where exploratory studies reveal that significant climate‐radial growth relationships exist. The purpose of this study was to develop a proxy record of climate change from tree rings and to reconstruct the late Holocene glacial history of two outlet glaciers spilling eastward from th
e Cambria Icefield. Dendroclimate investigations were conducted using mountain hemlock (Tsuga mertensiana) trees growing on three high‐elevation montane slopes. The three stands located along a 35 km transect cross date to form a master chronology for the region spanning 409 years (1596 to 2007 A.D.). Correlation analyses show that the radial growth of the regional tree‐ring chronology corresponds to variations in the mean June‐July‐August (JJA) air temperature. The relationship between the two variables was used to reconstruct mean JJA air temperature from 1680 to 2007 A.D.). The reconstruction illustrates warm and cool intervals that are synchronous
ito those derived from other paleoenvironmental research in this region. The proxy record also highlights annual to inter‐decadal climate variability likely resulting from atmospheric‐ocean circulation patterns described by the El Niño‐Southern Oscillat
ion and the Pacific Decadal Oscillation. The late Holocene behaviour of White and South Flat glaciers was investigated using radiocarbon dating techniques, dendrochronological cross‐dating techniques and geomorphological analysis of sedimentary units within the White and South Flat glacier forefields. Evidence for a First Millennial Advance (FMA) cumulating around 650 A.D. and early Little Ice Age (LIA) advances at 1200 and 1400 A.D. were documented. These advances are contemporaneous with the late Holocene activity of glaciers throughout the region, suggesting coherent broad‐scale climate forcing mechanisms have influence glacial mass balance regimes over at least the last two millennia. The dendroclimatological and dendroglaciological findings of the study provide the first annually‐resolved climate record for the region and help to enhance our understanding of late‐Holocene glacier behaviour in the Cambria Icefield Area. The thesis documents the complex interactions between climate and the radial growth of mountain hemlock trees in the Pacific Northwest, and describes the role that long‐term climate variability played in glacier dynamics during the FMA and LIA. / Graduate
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The Fraser Glaciation in the Cascade Mountains, southwestern British ColumbiaWaddington, Betsy Anne 05 1900 (has links)
The objective of this study is to reconstruct the history of
glaciation from the start of Fraser (Late Wisconsinan)
Glaciation to the end of deglaciation, for three areas in the
Cascade Mountains. The Cascade Mountains are located between
the Coast Mountains and the Interior Plateau in southwestern
British Columbia. The Coast Mountains were glaciated by
mountain glaciation followed by frontal retreat, whereas the
Interior Plateau underwent ice sheet glaciation followed by
downwasting and stagnation. The Cascades were supposed to have
undergone a style of glaciation transitional between these
two.
Terrain mapping on air photographs followed by field checking
was used to locate surficial materials and landforms
indicative of glaciation style and pattern. All three study
areas were glaciated by mixed mountain and ice sheet
glaciation. At the start of Fraser Glaciation, alpine and
valley glaciers formed around higher summits as occurred in
the Coast Mountains. At the glacial maximum the entire area
was covered by the Cordilleran Ice Sheet. Deglaciation was
largely by continuous downvalley retreat of active glaciers,
contrasting with downwasting and stagnation in the Interior
Plateau, and frontal retreat in the Coast Mountains. The
scarcity of fresh moraines in the cirques suggests that,
unlike in the Coast Mountains, most cirque glaciers were not
active at the end of glaciation. Only the highest north facing
cirques remained above the local snowline throughout
deglaciation and, as a result, glaciers in these valleys
remained active and retreated up valley.
The pattern of glaciation in the Cascade Mountains was similar
to that of other areas which underwent mixed mountain and ice
sheet glaciation, such as the Presidential Range in New
Hampshire, the Green Mountains in Vermont, mountain ranges in
west central Maine and the Insular Mountains on Vancouver
Island. However, deglaciation in al l areas was complex and
depended strongly on local conditions. For this reason local
patterns cannot be predicted easily on the basis of glaciation
style.
The value of an understanding of glaciation style to improve
the accuracy of terrain mapping was also investigated. It was
found that the model developed for the Cascade Mountains was
of some use in predicting the presence of fine-textured
material in valley bottoms and for the prediction of
glaciofluvial material overlying till . However fine-textured
sediments were not found in al l valleys which were predicted
to contain them. The model appears to be most useful as an
indicator of where to concentrate field checking in order to
locate fine-textured sediments.
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The Fraser Glaciation in the Cascade Mountains, southwestern British ColumbiaWaddington, Betsy Anne 05 1900 (has links)
The objective of this study is to reconstruct the history of
glaciation from the start of Fraser (Late Wisconsinan)
Glaciation to the end of deglaciation, for three areas in the
Cascade Mountains. The Cascade Mountains are located between
the Coast Mountains and the Interior Plateau in southwestern
British Columbia. The Coast Mountains were glaciated by
mountain glaciation followed by frontal retreat, whereas the
Interior Plateau underwent ice sheet glaciation followed by
downwasting and stagnation. The Cascades were supposed to have
undergone a style of glaciation transitional between these
two.
Terrain mapping on air photographs followed by field checking
was used to locate surficial materials and landforms
indicative of glaciation style and pattern. All three study
areas were glaciated by mixed mountain and ice sheet
glaciation. At the start of Fraser Glaciation, alpine and
valley glaciers formed around higher summits as occurred in
the Coast Mountains. At the glacial maximum the entire area
was covered by the Cordilleran Ice Sheet. Deglaciation was
largely by continuous downvalley retreat of active glaciers,
contrasting with downwasting and stagnation in the Interior
Plateau, and frontal retreat in the Coast Mountains. The
scarcity of fresh moraines in the cirques suggests that,
unlike in the Coast Mountains, most cirque glaciers were not
active at the end of glaciation. Only the highest north facing
cirques remained above the local snowline throughout
deglaciation and, as a result, glaciers in these valleys
remained active and retreated up valley.
The pattern of glaciation in the Cascade Mountains was similar
to that of other areas which underwent mixed mountain and ice
sheet glaciation, such as the Presidential Range in New
Hampshire, the Green Mountains in Vermont, mountain ranges in
west central Maine and the Insular Mountains on Vancouver
Island. However, deglaciation in al l areas was complex and
depended strongly on local conditions. For this reason local
patterns cannot be predicted easily on the basis of glaciation
style.
The value of an understanding of glaciation style to improve
the accuracy of terrain mapping was also investigated. It was
found that the model developed for the Cascade Mountains was
of some use in predicting the presence of fine-textured
material in valley bottoms and for the prediction of
glaciofluvial material overlying till . However fine-textured
sediments were not found in al l valleys which were predicted
to contain them. The model appears to be most useful as an
indicator of where to concentrate field checking in order to
locate fine-textured sediments. / Arts, Faculty of / Geography, Department of / Graduate
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Distribution and variability of some chemical parameters in the soils of a forested hillslopeRollerson, Terrence Paul January 1981 (has links)
Trends in soil chemistry are studied on a 300 meter long hillslope in the Cascade Mountain Range of southwestern British Columbia. Although trends are not wholly consistent from horizon to horizon, the following general statements can be made: pH tends to increase downslope; exchangeable calcium, exchangeable magnesium and cation exchange capacity decrease noticeably downslope; carbon may decrease slightly downslope; nitrogen, carbon/nitrogen ratio, percent base saturation, exchangeable sodium and exchangeable potassium remain effectively constant downslope. Soil chemistry is shown to be related to horizon, slope position and parent material. Variability among chemical species increases in the sequence: pH, percent base saturation, carbon/nitrogen ratio, cation exchange capacity, nitrogen, exchangeable calcium, percent carbon, exchangeable potassium, exchangeable sodium, exchangeable magnesium. Variability fluctuates among soil horizons but not so noticeably with slope position. A slight increase in variability with the size of the area sampled is evident. / Land and Food Systems, Faculty of / Graduate
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Examining brook trout invasion into bull trout streams of the Canadian RockiesWarnock, Will G January 2012 (has links)
Brook trout invasion into bull trout streams is variable, and likely influenced by a suite of
biotic and abiotic factors. Field observations revealed that brook trout dominated the fish
community over bull trout in warmer sites that had undercut banks; in contrast, bull trout
dominated in colder sites that had a high amount of large substrate cover, and where
alternate non-native species were present. Laboratory studies of competition between the
two species revealed that bull trout use a scramble foraging tactic, whereas brook trout
use a territorial tactic. Bull trout outcompeted brook trout when fish density was low and
habitat complexity was high, as this scenario reduced the effectiveness of the aggressive
territorial foraging strategy of brook trout. Bull trout from a migratory population
competed more successfully against brook trout and had higher rates of oxygen
consumption than those from a resident population. This combined field-lab study points
to some of the abiotic and biotic factors that affect competition between the two species,
and may influence the outcome of brook trout invasion into bull trout streams. / xiv, 184 leaves : ill. ; 29 cm
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Lake sediment-based sediment yields and erosion rates in the Coast Mountains, British ColumbiaOwens, Philip Neil January 1990 (has links)
Lake sediments have been identified as an alternative to contemporary stream monitoring to establish catchment sediment yields and infer erosion rates. This is due primarily to the longer time period over which the former is based, which makes established yields and rates more representative of means or trends in sedimentation. Studies using lake sediments to establish sediment yields have generally assumed that all the sediment contained within a lake is derived from erosion of the catchment under investigation. This study undermines this assumption by constructing a comprehensive lake sediment budget to asses the relative contributions from various sources. Late Holocene (the last 2350 years) rates of sediment yield and erosion are established for 3 small (<1 km²) catchments that straddle timberline (1620 - 1850 m above sea level) in the Coast Mountains of British Columbia.
Due to the temporal and spatial variability of sedimentation in lakes, sediment cores for each lake were taken using a multiple-core approach. Chronology was established by the presence of a dated tephra layer. Once the cores were extracted, corrections were made for sediment derived from aquatic productivity (organic matter and biogenic silica), regional aeolian dust input, the erosion of lake banks and for outflow losses. These sources of sediment could account for between 55 and 99% of the sediment contained within the 3 lakes. Lake trap efficiency ranges from low to >70%. Once corrected, estimates of sediment yield range from 4 and 244 kg km⁻²yr⁻¹. The rate of regional aeolian deposition indicates that, in certain areas, these catchments are undergoing net deposition and not net erosion. The implications for lake sediment-based sediment yields and erosion rates are examined. When placed in a regional context sediment yields are more than 1 order of magnitude lower than larger scale basins due to changes in sediment storage. The spatial and temporal representativeness of the data are also evaluated. / Arts, Faculty of / Geography, Department of / Graduate
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