Earth is a thermal engine that dissipates its internal heat primarily through convection.
The buoyant rise of hot material transports heat to the surface from the deep
interior while colder material sinks at subduction zones. Mid-ocean ridges and hotspots
are major expressions of heat dissipation at Earth’s surface, as evidenced by their
abundant volcanic activity. Ridges and hotspots, however, could differ significantly
in their origins. Ridges are linear features that wind more than 60,000 km around the
globe, constituting the major diverging boundaries of Earth’s tectonic plates. Hotspots,
on the other hand, are localized regions of abnormally robust magmatism and
distinctive geochemical anomalies.