Riding the Wilson Cycle Plate tectonics was originally a theory
about oceans. It described oceans opening and closing: how
oceanic crust is created at mid-ocean ridges during seafloor
spreading and how it is consumed at trenches by subduction.
Apparently unique to the terrestrial planets (Earth, Mars, Venus
and Mercury), plate tectonics is also a particularly efficient
style of mantle convection, a relentless machine driven by
Earth’s heat. But the theory itself, first proposed in the 1960s
to supersede the older theory of continental drift and to
include the newer concept of seafloor spreading, has since
expanded in scope. As scientists develop increasingly better
techniques to investigate crustal and mantle processes, they are
also developing new, groundbreaking ways of thinking about this
most fundamental geological theory. One of the most significant
advances appeared in a seminal 1966 Nature paper by J. Tuzo
Wilson, in which he expanded the theory of plate tectonics to
include the continents. While the o