DISTRIBUTION AND CHARACTERISTICS OF LATE WISCONSIN DELTAS IN SOUTHERN MICHIGAN, USA

A map is presented showing deltas formed during the late Wisconsin (MIS 2), as ice retreated from southern Michigan. The map is based on the interpretation of USGS 7.5’ quadrangle topographic maps, topographic profiles created in ArcMap using a seamless 10m NED DEM, county-level NRCS soils data, and depth profiles constructed from digital water well and oil/gas logs downloaded from the Michigan Geographic Data Library. All of the mapped deltas are now abandoned and therefore relict. Most of the deltas, e.g., Raisin, Clinton, and Black River deltas (I-III) in southeastern Michigan, the Rifle River, Jack Pines, and Sevenmile Hill deltas in northeastern Michigan, are sand-textured and fan-shaped and best characterized as wave-dominated deltas. Other deltas (Rochester, Allendale, and the Cass River) are more elongate and illustrate multiple distributary channels associated with fluvial-dominated systems. The Slagle Creek and Sturgeon River deltas were probably formed by the coalescence of multiple deltas and alluvial fans. The wave-dominated deltas appear to have formed along the margin of large basins where there is potential for significant wave energy, whereas the fluvial-dominated deltas appear to have formed along the margin of restricted basins characterized by limited wave energy. It is our hope that this poster will generate discussion of the processes associated with lacustrine shorelines in southern Michigan, and their likely chronologies.