LATE GLACIAL ONTARIO LOBE ICE ON THE NIAGARA PENINSULA: HOW FAR DID IT GO?
High-resolution digital elevation data, collected as part of the southwestern Ontario orthophotography project (SWOOP 2010, 2015), were released as digital surface models in 2015. These datasets reveal complex landform relationships that could not be detected on older elevation models. Within the Niagara Peninsula area, encompassing 5000 km2 between lakes Erie and Ontario, the extent of older drumlins, a series of till cored moraine ridges located above the Niagara escarpment, ice-contact delta complexes and grooved and fluted bedrock along the escarpment edge provide insight on the most recent ice flow direction and extent. Preliminary results from 95 continuously cored boreholes drilled by the OGS from 2014 to 2016 show that Halton Till and associated deposits (stratified ice-contact sediments and interbedded diamictons) form a prominent marker horizon in the subsurface, separating fine-textured glaciolacustrine sediments into upper and lower packages. The influence of the ice advance is also apparent beyond the former ice margin as increased sediment loads resulting in deposition of coarser (silty) rhythmites.
By comparing the surficial morphological and sedimentary characteristics with high-quality drilling results, the extent of the Port Huron phase ice advance can be confidently mapped into the subsurface with more accuracy than was possible using water well and monitoring well records.