Abstract

The flow directions of ice lobes within the Erie basin may be deduced from heavy-mineral assemblages of the Hayesville, Hiram, and Ashtabula tills deposited during the Port Bruce Stade after the Erie Interstade. These tills have heavy-mineral assemblages dominated by purple garnet, green hornblende, and clinopyroxene. Oolitic hematite occurs in all tills, but is dominant in the Ashtabula Till. The probable source of hematite is the Furnaceville Ironstone Member of the Clinton Group which crops out south of Lake Ontario. Trilinear plots of purple garnet – red garnet – epidote suggest that the eastern Grenville Subprovince is the provenance of all three tills. Southwestward-flowing ice of an Ontario–Erie lobe deposited these tills in the Erie basin. The Huron–Erie lobe did not deposit tills along the south shore of Lake Erie after the Erie Interstade.

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