Morphology and GPR stratigraphy of a frontal part of an end moraine of the Laurentide Ice Sheet : Paris moraine near Guelph, ON, Canada

Abstract During deglaciation, the Laurentide Ice Sheet developed lobate ice termini in the Great Lakes area. Where the lobes remained quasi-stationary for considerable time and sediment was supplied by the glacier, end moraines fronted by outwash plains were formed. One of the best examples in southern Ontario is the Paris Moraine formed by the Lake Ontario lobe. This study is a detailed examination of the morphology (transverse and longitudinal) of part of the Paris Moraine near Guelph, Ontario, and an analysis of the stratigraphy as derived from borehole information and Ground Penetrating Radar (GPR) surveys. Parts of the northwestern frontal zone of the moraine are characterized by c. 30 m high, semi-isolated hills composed in great part by aprons (fans) of debris-flow and waterlaid sediments. To the southeast, these hills are backed by moat-like depressions similar to those formed by ice-push, generating “hill-hole” morphology. The ice-push effect is corroborated by evidence of folding and dislocation in the GPR profiles. Farther southeastward still, the main body of the end moraine is characterized by hummocky-topography typical of differential melting of sediment-charged stagnant ice.