Abstract

Clay-mineral analyses have been used to define two Late Wisconsinan till sheets of the Saginaw Lobe in southwestern Michigan. Bedford till can be traced along the ground surface from the Lansing Moraine southward to exposures within the Kalamazoo Moraine, and Fulton till can be traced in the subsurface southward from the Lansing Moraine, through a series of bore-holes, to exposures within the Tekonsha Moraine. Both tills are sometimes separated by a layer of sand and gravel. The presence of sand and gravel between the Bedford and Fulton tills further suggests that a significant retreat (>60 km) of the Saginaw Lobe occurred between the formation of the Tekonsha and Kalamazoo Moraines.

Morpho-stratigraphic correlations between moraines of the Saginaw and Huron-Erie Lobes suggest that the interval between the deposition of the Bedford and Fulton tills is probably time equivalent to the Erie Interstade. Correlations between moraines of the Lake Michigan and Saginaw Lobes in southwestern Michigan also suggest that the Erie Interstade occurred in the Lake Michigan Lobe between the deposition of Ganges and Saugatuck tills.

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