EOLIAN SAND IN LACUSTRINE SEDIMENTS: A PROXY FOR RELATIVE WATER LEVELS OF LAKE MICHIGAN

Eolian sand within lacustrine sediment of trapped embayments along the western coastline of Michigan, can be used as a proxy for Lake Michigan water levels. Numerous vibracores from Silver Lake in Oceana Co., presently separated from Lake Michigan by a barrier/dune complex, reveal variations in sand quantity from 6.6 ka years ago to present. The perched dune model, which describes enhanced sand dune activity driven by rising lake levels destabilizing shoreline bluffs, is used to explain the sand variations in Silver Lake. Wintertime storminess enhances sand dune activity and niveo-eolian transport of sand across frozen Silver Lake. Such niveo-eolian transport has been empirically observed. When the ice melts, the sand is introduced into the lake. Plots of weight percent sand from Silver Lake cores display an in-phase relationship with the lake level curve of Lake Michigan, which is based on dated beach ridges of known elevation. High values of sand in Silver Lake correspond to high stands of Lake Michigan since the Nipissing II phase, which is the limit of the lake level curve. Both, high values of sand in Silver Lake and high stands of Lake Michigan, exhibit a periodicity of ~160-200 years. Enhanced niveo-eolian activity, recorded within Silver Lake, is presumably driven by quasi-periodic climatic changes reflected in high stands of Lake Michigan.