| Factors controlling the development, migration, and stability of an incipient parabolic dune in Pinery Provincial Park, Ontario were investigated in terms of grain size characteristics, rates of sediment transport, and local and regional winds. The parabolic dune, situated approximately 60 meters inland of Lake Huron, is dominated by sparsely scattered dune grass species of marram grass (Ammophila breviligulata), sand reed (Calamovilfa longifolia), and sea rocket (Cakile edentula). Small tree species of red cedar (Juniperus virginiana) and eastern cottonwood (Populus deltoides) emerge and increase in number beyond the parabolic dune. Mean grain sizes along a profile were coarsest on the beach and interdunal area, and finest through the foredune and the parabolic dune, which was to be expected. The primary depositional processes responsible for the evolution of the dune is grainfall through vegetation, with intermittent, short periods of tractional deposition. Sand trap samples revealed that twice as much sand was transported through the interior of the dune (55.5 kg), than at the mouth (22.8 kg), over a one year period. Transport through the mouth exhibited greater directional variability than the interior, where transport was dominated by a landward, northerly trend. Overall, the amount of sand transported did increase as mean wind speed increased, with the exception of April. Seasonally, transport through the interior reached a maximum during the spring/early summer, decreased through late summer and fall, until it reached a minimum during winter. Transport through the mouth reached its maximum during the late summer/fall season, declined during the winter, and maintained a relatively constant low from the winter though the spring/early summer season. (Abstract shortened by UMI.)... |
