Ever since Alfred Wegener proposed the theory of continental drift in 1912, we have been aware that blocks of the Earth’s lithosphere are moving with respect to each other. With the advent of plate tectonics in the 1960s, these moving blocks became identified with the tectonic plates that tile the Earth’s surface. We now have accurate measurements of plate motion speeds, which range from about ½ a cm per year to 10 cm per year. But there is still no general consensus as to what makes plates move. Broadly speaking, there are two competing explanations. In the first, the plates ride on top of convection cells of a vigorously convecting mantle. In the second, it is the forces acting on plate boundaries, principally the pull of dense lithospheric slabs subducting into a less dense mantle that drive the plates. Douwe van Hinsbergen is a Professor of Global Tectonics and Paleogeography at the University of Utrecht. He has reconstructed the history of plate motions in various locations around the world with the primary goal of using this history to understand the dynamics of the mantle. And his latest research is directed to shedding light on the long-standing question as to what drives tectonic plates.

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