LATE-PLEISTOCENE WIND-FLOW PATTERNS AND DUNE FORMATION IN NORTH-CENTRAL LOWER MICHIGAN
This study focuses on the geomorphic history of the Rosco dune field, which lies in north-central Lower Michigan. The dune field is about 23 km2 in size, lies immediately east of the Muskegon River, and contains a variety of parabolic dunes that have westerly orientations. In order to estimate the time of dune formation, 10 samples were collected for optical (OSL) dating. Ages indicate that the dunes formed ~ 11,000 years ago. This episode correlates with a period of dune formation in central Wisconsin and the development of spits in northeastern Lower Michigan associated with glacial Lake Algonquin. The spits formed from dominantly easterly winds and thus support modeled anticyclonic flow over the Laurentide Ice Sheet at that time. Given the close proximity (~100 miles) of the westerly-orientated Houghton dunes to these spits, this study supports the hypothesis that easterly winds were confined to a narrow zone along the ice front.