Answer:
Hot, less dense material below Earth's crust rises up to the surface at divergent plate boundaries. This process is called seafloor spreading.
Explanation:
Convection currents in the Earth's mantle are caused by heat from the core and the mantle itself. As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise. As it rises, it cools, becomes denser, and sinks back down, creating a continuous cycle.