Application of LiDAR and geophysics to archaeological investigations in the upper Mississippi River valley

Red Wing, Minnesota, is located in the upper Mississippi River valley near the northern margin of the Driftless Area, a portion of southeast Minnesota and western Wisconsin that was not glaciated in the late Quaternary characterized by river valleys deeply dissected through a sequence of Paleozoic sediments. River terraces are prominent in the field trip area. These terraces developed in two steps. Glacial outwash filled the valleys in the late Quaternary, followed by at least two pulses of incision associated with meltwater drainage from large glacial lakes to the north, including glacial Lake Agassiz. Following the last pulse of meltwater incision, tributary streams built sediment fans in the valley floor which the post-glacial Mississippi River was not able to erode. As a result, large lakes-including Lake Pepin-developed in the valley bottom. Lake Pepin has subsequently shrunk by delta progradation from the north. Evidence of Native American habitation in the area extends to Paleoindian time (ca. 11 ka B.P. calendar), but there is limited evidence of large, horticultural populations until A.D. 700. This timing coincides with the advance of the Lake Pepin delta front from St. Paul south to the Red Wing area. Large village sites were strategically placed on terraces above the Mississippi. Recent application of LiDAR (light detection and ranging) and resistivity surveys have aided ongoing archaeological investigations in the Red Wing area. Burial mound groups are visible in airborne LiDAR elevation data, and resistivity surveys have revealed evidence of an extensive village at the Silvernale site. © 2011 The Geological Society of America. All rights reserved.