Monthly Archives: September 2018

GSW meeting 1533: Wednesday, October 3

~ The 2018 Bradley lecture ~

Jane Willenbring
Scripps Institution of Oceanography
“Not Feeling the Buzz: Tectonics – Not Climate – Limits Heights of Mountains”

The potential to rapidly denude topography at and above the glacier Equilibrium Line Altitude (ELA), irrespective of uplift rates, rock type or pre-existing topography, is explored in the glacial buzzsaw hypothesis. In this talk, I offer evidence from cosmogenic nuclide data and numerical models that (1) topography can persist in a state of transience for millions of years through feedbacks that can promote and maintain subdued topography dissected by valleys and that (2) the glacial buzzsaw cuts down–not across. Finally, we compiled tectonic, topographic, and erosion rate data from Arc-Continent convergent margins where the convergence rate is known (Andes, Central America, Cascadia, British Columbia, Alaska, Taiwan, and Makran). Erosion rates and elevation maxima and mean elevations correlate linearly with plate convergence rates. Importantly, mountain peaks in three heavily glaciated mountain ranges (Alaska, Cascadia, and South Chile) do not deviate from the trend of unglaciated mountain ranges such as the Central Andes and Taiwan. That mountain ranges with different climatic characteristics fall within the same trend implies that tectonics is the primary control of mountain range mass and heights–not glaciers.

Jane Willenbring is an Associate Professor at Scripps Institution of Oceanography, UC San Diego. She joined Scripps in the summer of 2016 and is the Director of the Scripps Cosmogenic Isotope Laboratory. She received her B.Sc. from North Dakota State University, where she was a McNair Scholar, and a Master’s degree from Boston University. She received her Ph.D. in Earth Sciences from Dalhousie University in Halifax, Nova Scotia Canada and was named an Izaak Walton Killam Laureate. She was a Synthesis Postdoctoral Fellow through the National Center for Earth-Surface Dynamics, and an Alexander von Humboldt Fellow at GFZ Potsdam, Germany. Jane was previously a professor at the University of Pennsylvania and a Blaustein visiting professor at Stanford University. She is a Fellow of the Geological Society of America and in 2016 was awarded an NSF Career grant.