NEW INSIGHTS ON GLACIAL LAKE EVOLUTION IN THE SOUTHEASTERN PART OF THE LAKE HURON BASIN BASED ON SURFICIAL SEDIMENT MAPPING, SEDIMENT DRILLING, AND REMOTELY-SENSED DATA IN SOUTHERN ONTARIO

Results from recent surficial mapping and sediment drilling investigations undertaken by the Ontario Geological Survey provide abundant new data on the timing, extent, and evolution of deglacial lake bodies in the southeastern part of the Lake Huron basin.

We provide optically-stimulated luminescence (OSL) dates from various sediments associated with water plane indicators (deltas and beaches) of glacial Lake Schomberg, an early, high-level, ice-dammed lake that spanned much of the area to the south of Georgian Bay. These are the first reported dates for this lake body, and assist in providing constraint on the timing of final ice retreat in the area. OSL dates and radiocarbon age determinations are reported from sediments associated with multiple stages of glacial Lake Algonquin, providing a more detailed picture of the transgression from the Kirkfield Low phase to main Lake Algonquin. Organic material was also retrieved from post-Algonquin sediments as well as later transgressive deposits prior to the Nipissing Phase of the upper Great Lakes.

Dated deposits are correlated to shoreline features across the basin to reconstruct the paleogeography of the lake and retreating ice margins. Select shoreline features associated with equivalent lake phases from different areas in southern Ontario are highlighted to demonstrate their potential for future study, which will assist in correlating lake level fluctuations at larger scales across the entire lake basins.