The OSL chronology of eolian sand deposition in a perched dune field along the
northwestern shore of Lower Michigan
Bradley E. Blumer, Alan F. Arbogast, and Steven L. Forman
Extensive coastal dunes occur in the Great Lakes region of North America, including northwestern Michigan
where some are perched on high (~100 m) bluffs. This study focuses on such a system at Arcadia Dunes and
is the first to systematically generate optical ages from stratigraphic sections containing buried soils. Dune
growth began ca. 4.5 ka during the Nipissing high lake stand and continued episodically thereafter, with periods
of increased sand supply at ca. 3.5 ka and ca. 1.7 ka. The most volumetrically dominant phase of dune
growth began ca. 1.0 ka and continued intermittently for about 500 years. It may have begun due to the combined
effects of a high lake phase, potential changes in lake hydrodynamics with final isostatic separation of
Lake Superior from Lakes Michigan and Huron, and increased drought and hydrologic variability associated
with the Medieval Warm Period. Thus, this latest eolian phase likely reflects multiple processes associated
with Great Lakes water level and climate variability that may also explain older eolian depositional events.
Comparison of Arcadia ages and calendar corrected 14C ages from previous studies indicate broad chronological
agreement between events at all sites, although it appears that dune growth began later at Arcadia.