In geology, a hypothetical region of high thermal activity in the Earth's mantle. Hot spots are believed to be the origin of many chains of ocean islands, such as Polynesia and the Galápagos.
A volcano forms on the ocean crust immediately above the hot spot, is carried away by plate tectonic movement, and becomes extinct. A new volcano forms beside it, above the hot spot. The result is an active volcano and a chain of increasingly old and eroded volcanic stumps stretching away along the line of plate movement.