THANKS to a load of balls, we’re a little closer to understanding how the continents, mountains and oceans came to be.
The mantle flows in convection “cells” as it warms and rises, then cools and sinks. Rocky plates riding on top are smashed together and pulled apart to form mountains and oceans. Over geological timescales, the cells’ flow changes direction, but why they do so is a mystery. One 40-year-old theory is that when thick continental crust blankets the cell beneath it, heat is trapped. This creates rising currents that alter flow direction.
Now Jun Zhang and colleagues at New…
