Estimating the Time Since Final Stabilization of a Perched Dune Field Along Lake Superior
The Nodaway dune field is perched along Lake Superior in Upper Michigan. This study uses absolute and relative-age dating methods to test the hypothesis that the dune field finally stabilized after the Nipissing high stand, about 4,000 years ago. Surface soils on snouts of all dunes are moderately developed Spodosols, indicating that dunes stabilized within a few hundred years of each other. One thermoluminescence date provided an age of 8 ka from soil parent material, but is probably overestimated due to residual thermoluminescence. Subsequent optical stimulated luminescence and accelerator mass spectrometry age estimates indicate that the most recent accumulation of sand occurred between ˜3.7 and 3.0 ka. This interval suggests one of three possibilities: 1) that the dune field was reactivated during the Algoma high stand and then stabilized; 2) that the dune field stabilized gradually, probably as sand supply diminished after the Nipissing high stand; and 3) that a combination of these two processes occurred.