Landscape evolution in south-central Minnesota and the role of geomorphic history on modern erosional processes

[摘要] The Minnesota River Valley was carved during catastrophic drainageof glacial Lake Agassiz at the end of the late Pleistocene. The ensuing base-leveldrop on tributaries created knickpoints that excavated deep valleys as they migratedupstream. A sediment budget compiled in one of these tributaries, the Le Sueur River,shows that these deep valleys are now the primary source of sediment to the MinnesotaRiver. To compare modern sediment loads with pre-European settlement erosion rates,we analyzed incision history using fluvial terrace ages to constrain a valley incisionmodel. Results indicate that even though thedominant sediment sources are derived from natural sources (bluffs, ravines,and streambanks), erosion rates have increased substantially, due in part to pervasivechanges in watershed hydrology.

[学科分类] 地质学

[关键词] Fire safety;fatal fires;smoke alarms