What type of tectonic plate boundary forms where two plates move apart?

A divergent boundary forms where two tectonic plates move apart.

As the plates separate, hot mantle material rises into the opening and partially melts. Cooling magma creates new oceanic crust, a process called seafloor spreading. Divergent boundaries are therefore major sites of crust production.

Most active divergent boundaries lie beneath oceans, where they form mid-ocean ridges. The Mid-Atlantic Ridge is a well-known example, extending through the Atlantic Ocean and separating several oceanic plates. On continents, divergence can create rift valleys, such as the East African Rift.

A divergent boundary is different from a convergent boundary, where plates move toward each other, and a transform boundary, where plates slide laterally past one another. Some spreading centers are offset by transform faults, but the overall plate motion at the spreading center is still divergent.