BOB HIRSHON (host):
Plate tectonics on hold. I’m Bob Hirshon and this is Science Update.
When the earth’s tectonic plates collide, continents and mountain ranges form. When the plates separate, ocean basins form. Until now, scientists thought the phenomenon was a continual process, driven by heat and pressure from volcanic activity under the earth’s crust. But Mark Behn of the Woods Hole Oceanographic Institute argues that constant plate tectonics fails to explain the observed thermal evolution of the earth.
MARK BEHN (Woods Hole Oceanographic Institute):
We know what earth’s temperature is today, and if we extrapolate backwards based on the current rate of cooling we would reach very high temperatures in the past, so high, that the earth would have been molten one billion years ago.
Instead, Behn and his colleagues propose that plate tectonics is an intermittent process, losing speed every time supercontinents form, which slows the cooling of the earth. I’m Bob Hirshon, for AAAS, the science society.