Richter receives society’s Wollard Award

The Geological Society of America presented its George Wollard Award to Frank Richter, the Sewell Avery Distinguished Service Professor in Geophysical Sciences, during its annual meeting in Denver Oct. 25 to 28.

Named for a University of Wisconsin geophysicist, the Wollard Award is given annually in recognition of outstanding contributions to geology through the application of the principles and techniques of geophysics.

Richter was honored for his pioneering work using fluid dynamics to discuss the driving mechanism of plate tectonics, the theory that the Earth’s surface is covered by a small number of plates in relative motion over a deformable interior.

Richter began pursuing this research as a graduate student at the University in the late 1960s, shortly after plate tectonics theory began a revolution in geologic thought. The 1961 merger of Chicago’s departments of Geology and Meteorology into a single Geophysical Sciences Department influenced his research topic.

Richter was looking for a way to combine his own background in solid-earth studies with the expertise of his thesis adviser, who specialized in the fluid dynamics of atmospheres and oceans.

Richter worked from the view that the fluid dynamics of plate tectonics was probably a variant of normal thermal convection, where motion is driven by the sinking of cold, dense material and the rising of warm, light material. He proposed that plates themselves were the main convective elements, that motions from below did not drive them.

Further refinement of this idea involved showing both theoretically and experimentally that any small-scale convective motions under the moving plates would take the form of rolls with axes aligned in the direction of the overlying plates’ motion. Because these “Richter Rolls” exert no force in the direction of the overlying plates’ motion, they are not part of the driving mechanism, which further reinforces the idea that the plates must be self-driven.