PIECING IT TOGETHER: REGIONAL CORRELATIONS OF ICE MARGINS AND GLACIAL-PROGLACIAL LANDFORMS IN SOUTHERN ONTARIO

New digital surface models obtained from the Ontario Ministry of Natural Resources and Forestry have greatly improved visualization of the landscape of southern Ontario. Use of high-resolution terrain datasets assist in developing detailed and reliable Quaternary maps, which serve as essential baseline information for many land use, geologic and hydrogeologic investigations across the province. When the new terrain data are combined with the three-dimensional modelling and surficial sediment mapping investigations undertaken by the Ontario Geological Survey, then identification, characterization and correlation of glacial sediments and landforms across the entire southern part of the province are enhanced. By using these new data sets, understanding of glacial events will be advanced in several ways: make clearer the extent and relationships of late-glacial moraines; identify new crosscutting or superimposed glacial erosional and depositional features; highlight the links between esker distribution and former ice-marginal positions; improve elevation constraints and visualization of raised shorelines and littoral features in former glacial lakes; and identify ice-marginal landscapes with abundant closed depressions unrecognizable in previous terrain models.

Preliminary analyses of the terrain data allow detailed reconstructions of previous ice margins, highlighting the interactions and activity of ice lobes in the Great Lakes basins. Eskers are commonly observed superimposed on areas with elongated streamlined forms, both of which generally terminate at recessional and/or end moraines, suggesting a strong relationship between subglacial hydrology and ice lobe and/or stream dynamics. Analysis of strandlines and recessional moraines shows the intimate relationship between water levels in Lake Huron and Georgian Bay and ice lobes occupying the basins during deglaciation.