The northeast coast of Graham Island is macrotidal, composed of unconsolidated sediments, and subject to extreme wind and wave conditions. Cape Fife coast is erosive, composed of sand to gravel, and is medium to low sloped with intertidal to subtidal bars. The north coast is mainly depositional, very low to steeply sloped, and composed of fine aeolian sands and cobbles. Rose Spit, trending north-northeast separates the two beaches. Cross-shore profiles documented seasonal morphologies, where active summer swash bar development is preceded by concave profile. This study identified that bars on the east coast are linked to erosive hotspots. There was a relationship between wavelength and amplitude of the bar and the erosive nature of the foreshore. It is proposed that bars protect against incident waves. Decadal and seasonal evolution of a portion of the northeast coast was compiled with the combination of aerial photography, bathymetric data and geomorphological mapping.

The marine gas hydrate stability zone (GHSZ) is sensitive to climatically driven temperature changes at the seafloor. This thesis reviews past studies of the GHSZ response to climate change, and presents the results of a numerical analysis of a marine gas hydrate stability model forced by an intermediate complexity climate model. Potential future climate scenarios are simulated. resulting in realistic predictions of seafloor temperature change over variable bathymetry. The average continental margin seafloor temperature increase is greater than the global seafloor average. and it is determined that even for CO2 concentrations held below present-day levels. the global GHSZ will decrease significantly. The experiments carried out here indicate that after 40 kyr the GHSZ volume will shrink by between 1% and 29%. based on various CO2 scenarios and parameterizations of thermal diffusivity and geothermal gradient. Regions which exhibit 100% GHSZ loss range from 1% to 9% of the prescribed continental margin. Results of this study suggest that the effects of future GHSZ loss may be felt by the exogenic carbon cycle within centuries and last for tens of thousands of years.

The goal of this study was to characterize the ecology and recreational boating activity at two popular anchoring sites located in the waters of the Gulf Islands National Park Reserve of Canada (Sidney Spit and Tumbo Island). The three components of the study were to characterize the distribution of eelgrass (Zostera marina L.). build an inventory of anchoring/mooring activity, and characterize the benthic infauna at each site. These observations were used to evaluate the impact of anchoring on the eelgrass and invertebrate communities. No visible loss of eelgrass was documented, but the results at one of the two sites support the hypothesis that benthic communities in high anchoring intensity areas are in poorer health than those in low anchoring intensity or mooring areas, a characteristic of communities residing in disturbed and fragmented eelgrass beds. Recommendations for site management and long-term monitoring are proposed based on these results.

In this study the contribution of post-critical reflections at the oceanic Moho to ground motions from mega-thrust events in the Cascadia subduction zone is examined. The hypothesis to be tested is that the Moho post-critical reflection is a primary component of the S-wave-field at large epicentral distances from a subduction zone thrust earthquake. Pseudo 3-D modeling using P-SV pseudo-spectral synthetic seismograms and ray tracing amplitude calculations are employed. Double couple line sources are initiated within a structural model for the Cascadia subduction zone that incorporates an updated Juan de Fuca slab geometry. Areas in which the oceanic Moho post-critical reflection is a primary component of the seismic wave-field are defined as a function of landward extent of rupture for the next mega-thrust event. For rupture extending landward of the down-dip limit of the seismogenic zone, Moho post-critical reflections create a broad maximum in peak ground motions at locations that fall within the Pacific Northwest urban corridor [Portland, Seattle. Vancouver. Victoria]. At these locations, ground motions from sources with dominant frequencies between 1 Hz and 3 Hz can be a factor up to 1.5 greater than those modeled in the absence of the oceanic Moho post-critical reflection. A second maximum is associated with the presence of forearc mantle serpentinization, which affords a route for post-critical reflections at the oceanic Moho to escape upwards toward the Earth's surface rather than being trapped in the oceanic crust wave-guide. The forearc mantle wedge acts to concentrate seismic energy within a narrow region at locations, just landward of major population centers.

Coalbed methane (CBM) is a growing resource for "clean" natural gas and is becoming of great interest for academic research. Despite much research already be done, geochemical investigations, especially with focus on the stable carbon and hydrogen isotope composition of CBM, are rare. For this study, over 1,000 CBM samples were analyzed. The samples were collected during 10 different sample campaigns from seven different coal bearing basins worldwide. Seven sample sets were collected during desorption experiments following drilling of exploration wells and three sample sets were collected from CBM producing wells. The considered coals range in maturity from sub bituminous A (min. 0.57%Ro) to anthracite (max. 4.55%Ro), cover a wide range of different maceral compositions and were accessed in depths between 10m and 1312m beneath surface. Samples cover a production time of up to 6312 hours and a desorption time of up to 2773 hours. The geochemical analyzes were carried out using GC—IRMS. Analyzes include gas composition (methane, ethane, propane, n—butane, i—butane and carbon dioxide) and the proportions of the different gas species, as well as stable carbon isotope ratios for all gas species and stable hydrogen isotope ratios for methane. The analyzed averaged and normalized gas composition of the considered samples reveals average proportions for methane between 44.3% and 98.7%, for ethane between 0% and 9.98%, for propane between 0% and 1.15%, for n–butane between 0% and 1.09%, for i–butane between 0% and 0.003% and for carbon dioxide between 1.34% and 53.9%. The gas composition does not show conclusive trends with increasing production/desorption time. Methane stable carbon isotope ratios vary with production/desorption time. Samples from production scenarios show a general depletion in 13C for methane with increasing production time and isotope shifts between -1.6% and -35.8%0. Samples from desorption experiment scenarios show mostly enrichment in 13C for methane with increasing desorption time and isotope shifts of up to -43.4%0, but also 12C enrichment was observed in some sample sets with isotope shifts of up to +32.1%0. Overall, the magnitudes of the observed isotope shifts vary considerably between different sample sets, but also within samples from the same source. The stable carbon isotope composition of methane does not display the expected composition of methane generated from coal. This indicates the influence of secondary processes. The secondary processes mixing, adsorption, desorption and diffusion/migration cannot be separated and considered individually, because they overlap and have identical directions for compositional and isotope alteration. The significant alteration of the considered gases generated from coal has therefore to be considered as a combined effect of the mentioned secondary processes. Because of multiple complicating factors it was not possible to delineate the presence of primary and secondary microbial gas, but due to the geologic context and the retentive ability of coal the presence of these gases is reasonable to assume. Indications were found in samples for the presence of gases generated from a Kerogen Type II shale in CBM gases. The unaltered molecular and isotope composition of CBM gases is unknown. This parameter cannot be estimated, because during the physical history of a coal seam, the coal probably had experienced the loss of gas accompanied by molecular and isotope effects of unknown extent and magnitude. Based on the current knowledge and the data available from this and other studies, a classification of CBM is unreasonable and more work is required for the establishment of a stable isotope systematic for CBM, including the separate experimental evaluation of molecular and isotope effects of adsorption, desorption and diffusion/migration of gases in coal.

The study area in northeast British Columbia extends from the Rocky Mountains in the west to the Fort Nelson Lowland in the east, and includes the westernmost extend of the Laurentide Ice Sheet (LIS) and the easternmost extend of the Cordilleran Ice Sheet (CIS) in the Late Pleistocene. Surficial mapping conducted over portions of the Fontas and Fort Nelson map areas (NTS 094I/SW and 094J/SE, respectively) provides information on sediment distribution and characteristics as well as glacial history. This information has direct implications for geotechnical investigations, aggregate resources and diamond exploration in the region. Non-glacial pre-Late Wisconsinan sediments occur at multiple sites along the Prophet River, providing a pre-glacial or interglacial history for the area. Geochemical analysis and clast lithologies were used to differentiate between sediments derived from the LIS to the east, and Montane/CIS glaciers to the west. The Quaternary stratigraphy of the Prophet River valley indicates the presence of a paleo-Prophet River valley system. Nonglacial deposits in the paleovalley include overbank fines and floodplain sediments interbedded with fluvial gravels. Macrofossils within horizontally laminated organic-rich black clay and silt are interpreted to indicate deposition in the floodplain of the paleo-Prophet River within oxbow-lakes and possibly also sag ponds. The climate is interpreted to be similar to present within a dominantly spruce forest. Wood found at one site provided a radiocarbon date of 49 300±2000 BP, while wood obtained from five other sites provided non-finite radiocarbon ages. In the Late Wisconsinan, the LIS advanced west-southwest into the study area, blocking existing east-flowing regional drainage, and forming an ice-dammed proglacial lake in the Prophet River valley. Ice overrode these sediments and deposited clast-poor clayey-silt till over the entire region. Thicknesses range from less than one metre to greater than twenty metres in the Prophet River valley. In river-cut sections near the Rocky Mountains in the Fort Nelson and Tuchodi Lakes map areas, potassium-feldspar rich granitoid and gneissic clasts, derived from the Canadian Shield, are generally found only east of the foothills, except along the Tetsa River valley. Near the mountain front, in Tuchodi River valley, outwash from Montane/Cordilleran glacial meltwaters was deposited before the LIS advanced and ponded the valley in the Late Wisconsinan. The geochemistry of 303 till samples collected throughout the study area is used to evaluate the regional glacial history inferred from stratigraphic and geomorphic data. Three different geochemical populations are recognized and corroborated by clast lithology (relative percent) from 56 till and glaciofluvial samples. One population, covering the northeast portion of the study area, was likely deposited by the LIS where it extended west into the Rocky Mountain front during the Late Wisconsinan. The second population suggests that the eastern extent of Montane/Cordilleran ice during the Late Wisconsinan was at least to the Rocky Mountain Foothills; however its easternmost position remains unknown. The third population can be attributed to Late Wisconsinan LIS reworking sediment deposited on the Interior Plains by the CIS, either in the Late Wisconsinan or earlier. During early deglaciation, the ice retreated to the east-northeast, impounding local drainage at the ice margin, forming Glacial Lake Prophet in the Fort Nelson map area and Glacial Lake Hay in the Fontas map area. Glacial lakes followed the retreating ice margin and drained through a variety of meltwater channels. The exposed glacial lacustrine plain became a source for sand dunes oriented southeast indicating katabatic paleowinds from the northwest (NTS 094I/SE).

This thesis presents new precision Global Positioning System (GPS) data, new analyses of earthquake deformation rates, and geological analyses, which constrain current deformation in Yukon and adjacent areas of the northern Cordillera. The integration of these data with additional thermal constraints facilitates the large-scale characterization of intense deformation associated with the collision of the composite oceanic-continental Yakutat block with North America in the corner of the Gulf of Alaska. Two main approaches are used to constrain the first-order current tectonic deformation pattern: (1) high-precision continuous and campaign GPS measurements; (2) seismic deformation rates calculated using earthquake statistics from the seismicity catalogue. The oblique Yakutat-North America collision is mainly accommodated by thrust and strike-slip faulting in the Saint Elias region, but associated deformation extends a great distance (> 800 km) into the North America crust of eastern Alaska, Yukon and western Northwest Territories. The data indicate westward motion and counter-clockwise rotation of the southeastern Alaska forearc along the arc of the right-lateral Denali fault. Right-lateral transpression north of the Denali fault in Alaska is accommodated by clockwise rotation of a number of NE-trending crustal blocks bounded by sinistral strike-slip faults. To the northeast of the Yakutat collision, GPS data indicate a northeastward crustal motion across the Cordillera towards the eastern foldbelt. Earthquake mechanisms indicate strain accommodation mainly by thrusting in the Mackenzie Mountains and N-S dextral strike-slip faulting in the Richardson Mountains. It is likely that a small northward component of motion is transferred further north to the offshore Mackenzie Delta region, where infrequent large earthquakes may result, despite little historical seismicity. An additional study is presented on the use of quantitative estimates of coastal coseismic subsidence in great earthquakes at the Cascadia subduction zone. Seismic hazard assessments for Cascadia megathrust earthquakes are largely based on the rupture area predictions of dislocation models constrained by geodetic and thermal data. The models for the 1700 great Cascadia earthquake are tested against compiled coastal coseismic subsidence for past great earthquakes, as estimated from paleoelevation studies. Models for strain accumulation of 550-800 years (in the range of event frequency from marsh dating and offshore turbidites), predict coastal subsidence in good agreement with marsh paleoseismic data, except that discrepancies occur at the ends of the subduction zone. Estimated slip from comparisons of dislocation models with marsh coseismic data for the 1700 event is consistent with the magnitude 9 earthquake indicated by Japanese tsunami records.

Traditional stock assessment methods do not incorporate remotely sensed ecosystem variables such as seafloor type, relief, and complexity. Incorporation of these and other ecosystem variables allows for targeting of species' optimal habitat during surveys. Recently, acoustic remote sensing methods have allowed us to gain insight into groundfish habitat. In June 2002, a geophysical survey was performed in selected fishing areas of Hecate Strait. While underway, single beam acoustic data were collected along survey lines utilizing a 50 kHz echosounder coupled with Quester-Tangent's QTC VIEW 5; a Huntec seismic system, and a dual frequency sidescan sonar system. Surficial sediment distribution and seabed features were mapped through examination of seismic, sidescan, and bottom grab data and compiled into a GIS. The surficial sediment classes were compared to bottom type classifications obtained from QTC single beam, with results showing the Gravel and Sand class from the surficial sediment data being classified best by the single beam system. Catch data from the groundfish bottom trawl fishery for the areas of interest were made available by the Department of Fisheries and Oceans Canada (DFO). The distribution of groundfish aggregates and individual fish species were compared to surficial sediment classes using correspondence analysis to investigate habitat associations. Results show that the Rock Sole aggregate had a habitat preference of gravel and sand mixture and the Dover Sole and Arrowtooth Flounder aggregates had a habitat preference of sandy mud. Correspondence analysis allows for a 2-dimensional view of multivariate categorical data which are the norm for habitat-based biological studies. Results suggest that the procedures developed in this work can improve stock assessment methodology and indicate that using various acoustic remote sensing techniques can be effective in characterizing seafloor habitats and ecological connections between groundfish species and seafloor types.

According to the "Out-of-Africa 2" theory of human evolution all living humans today descend from a group of Anatomically Modern Homo sapiens or Anatomically Modem Humans that evolved in Africa 200,000 years ago and subsequently migrated out of Africa and spread into the rest of the World around 100,000 years. As a result an interest has developed in establishing a concrete theory of the factors that compelled and/or motivated our ancestors to venture out of their African origins at this time. Interestingly, the Earth's Last Glacial Cycle also dates from this period--stretching from 115,000 to 10,000 years ago. Current paleoclimate evidence suggests that the climatic repercussions of this glacial cycle in Africa resulted in a shift towards a drier and somewhat cooler climate state and the fragmentation of the formerly extensive forested African landscape. As a result, theories of early human migration have cited African climate change during the late Pleistocene as a determinant; however, the mechanisms responsible for the development of hyper-arid conditions in Africa at this time have remained unresolved. Although, past global climate change has been ascribed to changes in radiative forcing and changes in atmospheric carbon dioxide, recent paleoclimate studies have revealed that African climate is sensitive to changes in SSTs in the Atlantic, as it appears that subtropical Africa was more arid when North Atlantic sea surface temperatures (SSTs) were cold during glacial periods. The forcing mechanism believed to be responsible for the development of these cold SSTs are the so-called Heinrich Events that are documented as massive surges of icebergs (from high-latitude ice sheets) into the North Atlantic Ocean during high-latitude glaciations. These Heinrich events resulted in the release of large quantities of freshwater into the North Atlantic, which in turn led to a weakening on the global ocean thermohaline circulation and widespread cooling throughout the region. In particular, marine sediment records from the Nordic Sea document a widespread cooling and ice-rafting event that occurred around 105 kya, known as Heinrich event 9. In order to investigate the climate processes responsible for promoting cooler and drier conditions in Africa during the migration event of AMH (around 100 kya) I used the University of Victoria Earth System Climate Model (UVic ESCM) to conduct two climate model experiments that compared the global-scale response of climate at 105 kya, in particular the Atlantic Ocean and the African climate system, to: 1) orbitally-controlled solar radiation and atmospheric carbon dioxide forcing appropriate for 105 kya and 2) the combined effect of orbitally-controlled solar radiation and atmospheric carbon dioxide at 105 kya, and North Atlantic freshwater forcing. The ultimate goal of this study is to understand how low-latitude and high-latitude climate processes affect the African climate. Overall the comparative analysis of these two climate model states revealed that the complex interaction between orbitally-controlled solar radiation and atmospheric CO2 forcing at 105 kya produced a significant part of the cooling and drying in Africa at this time interval. However, the model also indicated that the climate perturbations, caused by the freshwater forcing, amplified the cooling and drying that was already taking place in Africa due to orbital and CO2 forcing. Guided by paleoclimate data, archaeological data and the results of this study, I consider it likely that the development of hyper-arid conditions in Africa around 100 kya served as the impetus for the migration event of AMH out of Africa, as these climate changes would have rendered Africa unsuitable for hominid occupation at this time. These climate model results also provide compelling evidence that high-latitude cold events, induced by Heinrich Events, are strongly covariant with African aridity, and thus provide support to previous assertions that North Atlantic climate changes can be effectively propagated throughout the globe to produce seemingly simultaneous climate change.

Tectonic processes and seismic hazard along the west coast of British Columbia result from oblique convergence between the continental North America plate and the oceanic Pacific and Juan de Fuca plates. This dissertation integrates seismic and geodetic techniques to examine the tectonic interaction along these plate boundaries. The Queen Charlotte Fault zone is the transpressive boundary between the North America and Pacific plates along the northwestern margin of British Columbia. Two models have been suggested for the accommodation of the -20 mm/yr of convergence along the fault boundary: (1) underthrusting; (2) internal crustal deformation. Strong evidence supporting an underthrusting model is provided in this dissertation by a teleseismic receiver function analysis that defines the underthrusting slab. Forward and inverse modelling techniques were applied to receiver function data calculated at two permanent and six temporary seismic stations within the Islands. The modelling reveals a --10 km thick low-velocity zone dipping eastward at 28° interpreted to be underthrusting oceanic crust. The oceanic crust. which may be anisotropic, is located beneath a thin (28 km) westward shallowing (10°) continental margin. The majority of seismicity along the Queen Charlotte Fault zone plots within the modelled underthrusting crust, suggesting that these earthquakes are occurring on faults that extend down into the slab or they might be intraslab events. None of the earthquakes within the Queen Charlotte Basin have occurred deep enough to be intraslab earthquakes. The Wadati-Benioff seismicity may be inhibited beneath the basin by the hot young oceanic crust or by the short distance of underthrusting. GPS measurements have been recorded within the Queen Charlotte Islands during 8 years of campaign surveys. The crustal velocity field derived from the GPS data indicates northward margin-oblique motion of 10-15 mm/yr. Comparisons of the observed velocities with elastic dislocation modelling showed that the majority of the transpressive Pacific/North America motion is accommodated along the locked Queen Charlotte Fault zone and thrust fault with the remaining plate motion taken up by north-northeast migration of the margin at rates of --6 mm/yr. The migration is also supported by the stress pattern derived from focal mechanisms. However. the GPS determined deformation rates are much greater than the rates estimated in the Queen Charlotte Basin from the seismicity catalogue. The extra shortening could be accommodated by large characteristic thrust earthquakes within the basin. The deformation rates estimated from the seismicity along the Queen Charlotte Fault zone are consistent with the relative Pacific/North America plate motion: however. the seismic moment released by thrust earthquakes along the fault is insufficient to account for the component of convergence. This suggests that large thrust earthquakes may occur along the plate boundary. An additional part of this dissertation involved constraining the rupture parameters of the Nisqually earthquake. a M 6.8 event which occurred on February 28. 2001 within the subducting Juan de Fuca slab at the Cascadia subduction zone. The fault parameters of the event were estimated from moment tensor solutions, and by comparing the surface displacements from GPS and InSAR data. with predictions from elastic deformation models. The results are in agreement with the earthquake mechanism from waveform analyses. but provide substantially stronger constraints.