Mantle convection
Slow circulation of solid silicate rock in Earth's mantle, driven by heat from the core and radioactive decay, moving centimeters per year.
Rayleigh–Bénard convection: Fluid circulation arising when a layer heated from below becomes unstable to buoyant overturn. The general convection mode the mantle is treated as an instance of.
Arthur Holmes: Geologist who proposed in the 1920s–30s that mantle convection drives continental drift. First serious champion of convection as the engine behind moving continents.
Whole-mantle convection: The model in which slabs sink through the 660 km boundary to the core–mantle boundary in a single circulation. One pole of the layering debate, supported by seismic images of sinking slabs.
Mantle (geology): The silicate shell between crust and core, about 2,900 km thick, composing most of Earth's volume. The medium through which the convection circulates.
Plate tectonics: The theory that Earth's rigid outer shell is broken into moving plates interacting at their boundaries. The surface expression that convection was invoked to explain.
Mantle viscosity: The mantle's extreme resistance to flow, around 10^21 Pa·s, allowing solid rock to creep over geological time. Sets the pace of convection and how stress transmits between mantle and plates.
Continental drift: Wegener's hypothesis that continents move across Earth's surface, lacking a credible driving mechanism. Convection supplied the mechanism drift critics said was missing.
Layered mantle convection: The model separating upper and lower mantle circulation at the 660 km discontinuity. The rival model, motivated by geochemical evidence for isolated mantle reservoirs.
Radiogenic heat: Heat produced by decay of uranium, thorium and potassium, roughly half of Earth's present heat output. Internal heat generation that keeps the mantle convecting rather than cooling solid.
Mid-ocean ridge: Underwater mountain chains, about 65,000 km long, where new oceanic crust is created at divergent boundaries. The upwelling limb's surface trace, with ridge topography set by mantle temperature.