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Smith Lecture: The Meandering Path from River Dynamics to Valley Form

Ajay B. Limaye, University of Minnesota
Friday, February 9, 2018
3:30-4:30 PM
1528 C.C. Little Building Map
River channels are central features of many landscapes. In uplands, rivers carve valleys by migrating laterally and cutting downward into the landscape. Viewed in cross-section, valleys often show a textbook “V” shape. In other valleys, the path from the valley top to valley floor descends in discrete steps as river terraces, or in one steep drop into a river gorge. A longstanding question is whether these steps in valley topography record step changes in the history of river incision—driven, for example, by a pulse of tectonic uplift or a change in climate—or instead form by river erosion under steady forcing. Distinguishing these scenarios is central to reconstructing tectonic history and predicting landscape response to contemporary climate change. Numerical models provide a tool for predicting how rivers imprint the landscape, but face significant complications for treating bedrock valleys and common river shapes, including meandering and braiding.

I will present results from a new numerical modeling approach that fingerprints a background process of erosion by meandering rivers using surface ages and geometries. I will then apply this framework to test the likelihood of valley evolution driven by climate change for several North American river valleys. Finally, I will discuss an ongoing physical experiment to test how braided rivers shift across landscapes over geologic timescales. These case studies illuminate key challenges and opportunities for using river dynamics to interpret planetary landscapes and the geologic record.
Building: C.C. Little Building
Event Type: Lecture / Discussion
Tags: Lecture
Source: Happening @ Michigan from Earth and Environmental Sciences