Andrew D. Wickert

Abstract The introduction of European-style agriculture to the Upper Mississippi River Basin (U.S.) severely destabilized geomorphic systems and hydrologic regimes. Minnesota’s Whitewater River Valley exemplifies this phenomenon in microcosm as severe erosion, sedimentation, and flooding forced residents to abandon their villages and farmland within a century of habitation.

Abstract The imprint of glacial isostatic adjustment has long been recognized in shoreline elevations of oceans and proglacial lakes, but to date, its signature has not been identified in river long profiles. Here, we reveal that the buried bedrock valley floor of the upper Mississippi River exhibits a 110-m-deep, 300-km-long overdeepening that we interpret to be a partial cast of the Laurentide Ice Sheet forebulge, the ring of flexurally raised lithosphere surrounding the ice sheet.

Collapse of ice sheets can cause significant sea-level rise and widespread climate change. We examine the climatic response to meltwater generated by the collapse of the Cordilleran-Laurentide ice saddle (North America) ~14.5 thousand years ago (ka) using a high-resolution drainage model coupled to an ocean-atmosphere-vegetation General Circulation Model.