UBC Theses and Dissertations
Holocene lacustrine sedimentation in a small subalpine watershed in the Coast Mountains of British Columbia Souch, Catherine Jane
The lake sediments of Gallie Pond, a subalpine lake which drains the Goat Meadows watershed, a drainage basin in the Coast Mountains of south western British Columbia, were investigated to determine sediment transfers operating over the Holocene Epoch. Samples were collected from the terrestrial deposits of the Goat Meadows watershed and twenty six cores were taken from the lake sediments of Gallie Pond. Physical, chemical and mineralogical analyses were conducted on the terrestrial and lake sediment samples in order to determine sediment depth, size range and variability of specific properties of the sediments. The results indicate that the Goat Meadows watershed has remained a relatively low energy erosional system over the Holocene Epoch. The lithostratigraphy of the sediments best records the development of the lake from initial conditions of flowing water, to a peat bog and subsequently to an oligotrophic lake; a transition which may be related to regional palaeoclimatic change. Sediment yield from the watershed over the Holocene Epoch has varied by one order of magnitude. The mean rate is one and two orders of magnitude lower than the contemporary data for the watershed and the Coast Mountains region respectively. The source area for the clastic sediment within the watershed has changed from poorly weathered till to pedogenic sources with time, while the lake's organic matter has remained primarily allochthonous in origin. In the context of regional palaeoenvironments this study indicates rapid paraglacial erosion of glacial sediment in the immediate postglacial completed by ca. 10,000 years B.P.; an early date for the hypsithermal neoglacial boundary ca. 6300 years B.P.; progressive cooling of the three post hypsithermal neoglacial intervals; and, increased aeolian activity over the latter part of the Holocene Epoch.
Item Citations and Data