EAPS Department Lecture

Peter Molnar

Professor and Fellow of the Cooperative Institute for Research in
Environmental Sciences (CIRES), University of Colorado, Boulder
Department of Geological Sciences

Wednesday, February 5, 2014
3:45 p.m. – 5:00 p.m.
54-915, Green Building Lecture Room
Hosted by Tim Cronin

Mantle Dynamics, Isostasy, and Surface Topography

Abstract: We all agree that the earth is a dynamic planet.  Without dynamic processes to elevate terrain, erosion would destroy all subaerial topography, and sediment would bury all submarine topography.  Once we had a useful concept called “dynamic topography,” but now it is merely a slogan.  For example, numerous authors agree that southern Africa, roughly 1000 m high, exemplifies “dynamic topography,” but if some claim < 300 m and others >1200 km, do they really agree?  I contend that most long wavelength topography is isostatically compensated, as Airy and Pratt understood this in the mid-19th Century.  Dynamic stresses can account for ~300 m; Tibet stands 5000 m high.  Mantle flow beneath mountain belts may profoundly affect the structural and/or thermal history of such belts, but the stresses associated with that flow support a play a negligible amount (300 m) of high terrain.  Mantle dynamics creates high terrain by moving crust together and thickening it, by removing mantle lithosphere and replacing it with hotter asthenosphere, by injecting the athenosphere with hotter material upwelled from below, etc., in all cases in a state that is nearly (±300 m) in isostatic equilibrium.  Amen.

A reception in Building 54, Room 923 precedes the talk. 

All are welcome.

If you have any questions regarding the lecture, please contact Jennifer DiNisco at 617.253.2127 or jdinisco [at] mit [dot] edu. Reservations not required.

Sponsored by the Department of Earth, Atmospheric and Planetary Science, MIT.

Spring 2014 DLS Schedule

About the Speaker

Professor Peter Molnar

Peter Molnar

Professor Molnar's current research focuses largely on aspects of how mountain ranges form and continental lithosphere deforms, as well as the relationships between the tectonic evolution of the Earth and climate change, and the impact of climate change on erosion and the creation of relief. His work relies on geophysical methods and numerical experimentation on simple systems to understand how mass and heat are transferred in the continental lithosphere.

Professor Molnar received an A. B. in Physics at Oberlin College and then obtained his Ph.D. in Seismology at Columbia University in 1970. Post-graduation he was awarded Columbia's Higgins Graduat Fellowship and an Alfred P. Sloan Foundation Research Fellowship. In addition to a faculty position in the Department of Geological Sciences at the University of Colorado at Boulder since 2001, he has been awarded Visiting Professorships at Cornell, UC Berkeley, Université de Paris, Institut de Physique du Globe, Caltech, and the Univeristy of Washington. Previously, Professor Molnar served as Professor and a Senior Research Associate here at EAPS-MIT from 1974-2000.


Tim Cronin

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