SURFICIAL GEOLOGIC MAP OF SOUTHEAST TRAVERSE BAY, MICHIGAN

As part of the U.S. Geological Survey/EDMAP program a surficial geologic map of southeast Traverse Bay in lower Michigan was constructed based on field observations, topographic maps, soil maps, well-log data, and aerial photographs. The surficial geology is primarily related to subglacial and proglacial processes during the Michigan Subepisode of the Wisconsin Glacial Episode. The northern part of the map area (Williamsburg quadrangle and the Mission Peninsula) is characterized by a drumlinized landscape, associated with discontinuous, reddish sandy till over stratified sand and gravel and incised by two subglacial tunnel channels. The southern part of the map area is characterized by an elevated, southwest sloping outwash plain (Mancelona plain) formed during the Port Huron Phase. No till of the Two Rivers Phase of the Michigan Subepisode is recognized. Ancient bluffs parallel much of the shore of Traverse Bay and Elk Lake, representing former levels of glacial Lake Algonquin and Lake Nipissing. Also distinguished are several beach dune complexes with bars, beach ridges and dunes, as well as incised fluvial systems, all of which are post-glacial in origin.