Maximum-Limiting Ages of Lake Michigan Coastal Dunes:

Their Correlation with Holocene Lake Level History

Alan F. Arbogast and Walter L. Loope

Coastal geomorphology along the Great Lakes has long been linked with lake-level history. Some of the most spectacular landforms along the eastern shore of Lake Michigan are high-relief dunes that mantle lake terraces. It has been assumed that these dunes developed during the Nipissing high stand of ancestral Lake Michigan. This hypothesis was tested through stratigraphic analyses and radiocarbon dating of buried soils at four sites between Manistee and Grand Haven, Michigan.

At each site, thick deposits of eolian sand overlie late-Pleistocene lacustrine sands. Moderately developed Spodosols (Entic Haplorthods) formed in the uppermost part of the lake sediments are buried by thick dune sand at three sites. At the fourth locality, a similar soil occurs in a very thin (1.3 m) unit of eolian sand buried deep within a dune. These soils indicate long-term (~ 4,000 years) stability of the lake deposits following subaerial exposure. Radiocarbon dating of charcoal in the buried sola indicates massive dune construction began between 4,900 and 4,500 cal. yr B.P. at the Nordhouse Dunes site, between 4,300 and 3,900 cal. yr B.P. at the Jackson and Nugent Quarries, and between 3,300 and 2,900 cal. yr B.P. at Rosy Mound. Given these ages, it can be concluded that dune building at one site occurred during the Nipissing high stand but that the other dunes developed later. Although lake levels generally fell after the Nipissing, it appears that dune construction may have resulted from small increases in lake level and destabilization of lake-terrace bluffs.