INLAND EOLIAN SEDIMENTS AND THE POTENTIAL FOR ARCHAEOLOGICAL SITE BURIAL IN THE UPPER MIDWEST: WHAT ARE WE MISSING?

Eolian, or windblown, sediments cover portions of high alluvial terraces, paleochannels, relict dunefields, and upland plains throughout the upper Midwestern U.S. Eolian units form dunes, sand sheets, and loessic coversands, all of variable thickness and spatial coverage. Traditional interpretations suggest cessation of major eolian deposition sometime following the Last Glacial Maximum (~21 ka) but largely prior to human occupation of eastern North America starting at 14.5 ka. However, recent geochronological studies involving optically stimulated luminescence dating illustrate that eolian reactivation or remobilization events were common between 14.5 and 0.22 ka in Illinois, Indiana, Ohio, Michigan, and Wisconsin. These late Pleistocene through Holocene reactivation events largely appear in response to interregional climatic drivers such as increased aridity, decreased air temperatures, and increased wind speed. Significantly, the potential that eolian sediments blanket currently undocumented archaeological sites has received limited attention, especially in inland settings away from active floodplains. This presentation provides an update on an on-going project reviewing the nature, and timing, of post-14.5 ka eolian sedimentation in the upper Midwest. Currently, publications reveal an inventory of over 110 dates from inland eolian contexts. Preparation of 50-year bins of dates indicate correspondence between periods of increased eolian sedimentation and several paleoclimatic episodes such as the Younger Dryas, 8.2 ka cold event, and the Holocene Climate Optimum. Data also demonstrate meridional patterning of eolian sediments with thicker deposits, up to 12 meters in depth, in more northerly latitudes. Since current archaeology survey techniques, especially cultural resource management practices, typically fail to test much below 0.5 m on eolian landforms outside active floodplains, we risk missing significant portions of the archaeological record unless researchers enact more deep-testing protocols.