Paul Silver and former Postdoctoral Fellow Mark Behn, now at the Woods Hole Oceanographic Institution, are featured in this week’s Science for their proposal that plate tectonics may have been episodic. Scientists have generally assumed that the shifting of crustal plates has been slow but continuous over most of Earth’s history, but Silver and Behn suggest that plate tectonics may have come to a complete stop at least once in Earth’s history—and may do so again.

Silver and Behn point out that if the Pacific Ocean basin—where most of today’s subduction zones are located—were to close, as it is predicted to do in about 350 million years when the westward-moving Americas collide with Eurasia, then most of the Earth’s subduction zones would disappear with it. This ocean closure would effectively stop plate tectonics unless new subduction zones start up. Silver comments in the CIW press release: “The collision of India and Africa with Eurasia between 30 and 50 million years ago closed an ocean basin known as Tethys, but no new subduction zones have initiated south of either India or Africa to compensate for the loss of subduction by this ocean closure.” For more information, see the press release or Science.