Downflow glacial dispersal was investigated across the southern Ontario Canadian Shield-Paleozoic boundary along two detailed transects with surficial sediment sampling, sub-parallel to the dominant NNE-SSW transport direction. The transects started on the Shield, transited the Shield-Paleozoic boundary and extended into the Paleozoic basin, with the target sediments being the Newmarket Till and the Dummer Moraines. Geochemistry and mineralogy analyses of the clay + silt (<0.063 mm) size fraction, and pebble componentry provide the data required to elucidate the provenance of these two glaciogenic sediment formations, and their potential relationship to each other. Till thickness increases from <2 m (on the Shield) to >=10 m (on the Paleozoic basin) within 1 km south of the Shield-Paleozoic boundary. The Newmarket Till and Dummer Moraines both consist of carbonate-rich glaciogenic sediments, resultant from source material input dominated by limestone, shaly limestone and dolostone of the Paleozoic Gull River, Bobcaygeon and Verulam formations. Based on data from this study (matrix mineralogy and geochemistry, pebble componentry), we conclude that the Dummer Moraines are best termed as pebble-, cobble-, boulder-rich facies equivalents of the Newmarket Till. This study highlights the rapid transition in till matrix and clast content when transitioning from hard Canadian Shield lithologies to Paleozoic carbonate rocks and complexities along different glacial flowlines.