First continents
Geologic map of North America, color-coded by age. The reds and pinks indicate rock from the Archean . Mantle convection , the process that drives plate tectonics, is a result of heat flow from the Earth's interior to the Earth's surface. It involves the creation of rigid tectonic plates at mid-oceanic ridges . These plates are destroyed by subduction into the mantle at subduction zones . During the early Archean (about 3.0 Ga ) the mantle was much hotter than today, probably around 1,600 °C (2,910 °F),so convection in the mantle was faster. Although a process similar to present-day plate tectonics did occur, this would have gone faster too. It is likely that during the Hadean and Archean, subduction zones were more common, and therefore tectonic plates were smaller. The initial crust, formed when the Earth's surface first solidified, totally disappeared from a combination of this fast Hadean plate tectonic...