Describe the formation of hotspots and explain their relationship to plate movement.

Radioactive deacay in the Earth's core creates extremely high temperatures which heat the lower mantle. When radioactive decay is concentrated, local thermal currents are generated in the lower mantle. Plumes of magma rise from the lower mantle and burn through the Earth's lithosphere to create volanic activity on the Earth's surface. An example of a hotspot Hawaii.The hotspot remains stationary whilst the overlying plate moves. Using the example of Hawaii, the Pacific Plate is moving North-West at a rate of 5-10cm per year. This leaves a chain of extinct volcanoes which are no longer fed by the source of magma. The extinct volcanoes put pressure on the plate and therefore subside and become seamounts. Bends in the island chain show changes in the direction of plate movement. Hotspots are proof of Wagners theory of plate tectonics and plate movement.