Glaciated shelves develop under the influence of a more complex suite of processes than most non-glaciated shelves. Amongst the specific processes are the glacially-influenced sediment supply and the glacial-isostatic adjustment (GIA), which is largely responsible for the complex nature of regional relative sea-levels (RSLs). This study first characterizes the impact of GIA on the Mackenzie-Beaufort region by presenting a new set of RSL curves derived from a modern gravitationally self-consistent sea level model computing the effects of glacio-hydro isostasy, geoid changes, and true polar wander. The results of the RSL model present cross-shelf variations in the order of 100 m and along-shelf of 30 m during the LGM. The model also suggests a different timing and range to the single RSL curve presently used for this region. Depending on the location, the lowstand is modeled between 14 and 12 ka BP and reached between 85 and 140 m below present sea-level. These new findings are used in the second part of the study to evaluate the impacts of GIA along with other factors on the Late Quaternary evolution of the Canadian Beaufort Shelf. SedFlux, a process-based stratigraphic simulation model is used. Uncertainties associated with post-LGM conditions create difficulties in establishing good model parameterization. Thus, simulations are first performed on the Mackenzie Trough area, where data availability permits better evaluation and constraint of parameters that are then applied to the more data poor Eastern Beaufort Shelf environment. The results of the stratigraphic simulations suggest that the ice sheet margin in the Mackenzie-Beaufort region was more extensive than previously assumed. The impact of GIA on the stratigraphy of the Mackenzie Trough is to develop more progradational than retrogradational stratigraphic features. Simulations of the Eastern Beaufort Shelf suggest that a previously dated sample from the Uviluk borehole is not a RSL indicator as previously thought and by taking this into consideration, the borehole stratigraphy can be modeled. Modeling of multiple cycles of glacial/interglacial RSL with glacial outwash deposition supports the interpretation of the Late Quaternary geology suggested by Murton (2009). Finally, glacial outburst floods funnelling through the area would have mostly bypassed the shelf and contributed to its progradation. If flood water were directed to the Mackenzie Trough, the deposits are likely found within the lower wedge. / Graduate

In the late Pleistocene, most of British Columbia and northern Washington was covered by the Cordilleran ice sheet. The weight of the ice sheet caused up to several hundred metres of depression of the Earth’s crust. This caused relative sea level to be higher in southwestern British Columbia despite lower global eustatic sea level. After deglaciation, postglacial rebound of the crust caused sea level to quickly drop to below present levels. The rate of sea-level fall is used here to determine the rheology of the mantle in southwestern British Columbia. The first section of this study deals with determination of the postglacial sea-level history in the Victoria area. Constraints on sea-level position come from isolation basin cores collected in 2000 and 2001, as well as from previously published data from the past 45 years. The position of sea-level is well constrained at elevations greater than -4 m, and there are only loose constraints below that. The highstand position in the Victoria area is between 75-80 m. Sea level fell rapidly from the highstand position to below 0 m between 14.3 and 13.2 thousand calendar years before present (cal kyr BP). The magnitude of the lowstand position was between -11 and -40 m. Though there are few constraints on the lowstand position, analysis of the crustal response favours larger lowstand. Well constrained sea-level histories from Victoria, central Strait of Georgia and northern Strait of Georgia are used to model the rheology of the mantle in southwestern British Columbia. A new ice sheet model for the southwestern Cordillera was developed as older models systematically underpredicted the magnitude of sea level in late glacial times. Radiocarbon dates are compiled to provide constraints on ice sheet advance and retreat. The Cordillera ice sheet reached maximum extent between 17 and 15.4 cal kyr BP. After 15.4 cal kyr, the ice sheet retreated, and by 13.7 cal kyr BP Puget Sound, Juan de Fuca Strait and Strait of Georgia were ice free. By 10.7 cal kyr BP, ice was restricted to mountain glaciers at levels similar to present. With the new ice model, and using an Earth model with a 60 km lithosphere, asthenosphere with variable viscosity and thickness, and transitional and lower mantle viscosity based on the VM2 Earth model, predicted sea level matches the observed sea level constraints in southwestern British Columbia. Nearly identical predicted sea-level curves are found using asthenosphere thicknesses between 140-380 km with viscosity values between 3x10^18 and 4x10^19 Pa s. Predicted sea level is almost completely insensitive to the mantle below the asthenosphere. Modeled present day postglacial uplift rates are less than 0.5 mm yr^-1. Despite the tight fit of the predicted sea level to observed late-glacial sea level observations, the modelling was not able to fit the early Holocene rise of sea level to present levels in the central and northern Strait of Georgia.