Holocene landscape evolution and erosional processes in the le Sueur River, central Minnesota

The Minnesota River Valley was carved by the draining of glacial Lake Agassiz ∼13,400 years ago. Up to 85 m of incision along the proto-Minnesota River during this event spawned knickpoints that have been migrating upstream on tributaries, including the Le Sueur River in south-central Minnesota. This trip will explore the evolution of the Minnesota River Valley and Le Sueur River over the Holocene and discuss implications of landscape history for modern geomorphic processes. We begin with a brief tour of glacial stratigraphy and overview of the incised Minnesota River Valley. We then travel to the Le Sueur River to see bluffs, ravines, well-preserved strath terraces, and a paleo-channel that recorded incision and knickpoint migration of the Le Sueur River. We will discuss the process of landscape evolution in this otherwise lowgradient landscape and how the geologic history affects modern erosion and sediment loading to the Le Sueur, Minnesota, and upper Mississippi Rivers.