EPS Agassiz Colloquium


Monday, April 3, 2017, 12:00pm to 1:00pm


Haller Hall (Geological Museum, room 102)

Speaker: Professor Sean D. Willett from Eidgenössische Technische Hochschule (ETH Zurich), Switzerland

Title: "The Dynamics and Patterns of River Channel Networks"

Abstract: The planform geometry of river channel networks has long been regarded as a potential tool for inferring tectonic deformation, uplift history, or the signature of climate change. However, in practice, simple interpretation or models have produced ambiguous results. Some studies demonstrate that rivers are passive markers for strain, but other studies have demonstrated universal scaling relationships for geometric characteristics of drainage patterns, implying that channel dynamics respond to counter tectonic and climatic forcing in order to maintain a uniform geometry. In this talk, I explore some of the consequences of geometric scaling parameters and demonstrate how these can be used to assess the stability and transience of planform channel patterns at a continental scale. I show two examples, the first from central Europe, where the remnants of the Tethys Ocean are drained by the Danube river in an inherently unstable configuration. The second example is from the US midcontinent, where the Rocky Mountain foreland basin has experienced multiple cycles of sedimentation and erosion. Each cycle has reorganized the drainage pattern; in the modern High Plains we observe the transition from the depositional megafans of the Ogallala group to a younger erosional river network producing a landscape characterized by high plateaus, eroding bluffs and badlands.[Background Reading]