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APPLIED
SEDIMENTOLOGY TO NEARSHORE LACUSTRINE SANDS OF EASTERN LAKE ONTARIO, ONTARIO,
CANADA
I.P. MARTINI1 and J.K.P. KWONG2
1Department of Land Resource Science, University of
Guelph, Ontario Canada กก Coastal sandy deposits of eastern Lake Ontario have been analyzed, to establish whether they are relict (palimpsest) bodies or are actively being re-supplied by long-range, longshore drift. In the first case, dredging of offshore sands would foster strong shore erosion, in the second case, the damage may be small and temporary. This study has demonstrated that sands of the Pleistocene northshore bluffs of Lake Ontario and those of Presqu'ile Bay differ from those of Wellington and Athol bays on the western shore of Prince Edward County peninsula in eastern Ontario. Discrimination between sand types was based on textural parameters and heavy minerals concentrations. The differences are small, but detectable by accurate multivariate and statistical analyses. The concentrations of varieties of a single heavy mineral, such as red and purple garnets, allow identification of different sand sources from the crystalline Precambrian Shield. Essentially, these materials were transported into the study area by two glacial lobes, the sands were locally modified and mixed by lacustrine shore processes, but not sufficiently to obscure the legacy of the different sources. This difference indicates that there was no homogenization of the sands by long-range, longshore drift from the north to the south, thus nearshore sands of the Wellington and Athol bays cannot be dredged without irreparable damage to the shoreline environments where Provincial Parks have been established. |
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