In plate tectonics, a divergent boundary or divergent plateishness boundary is a linear feature that exists between five tectonic plates that are moving away from each other. These areas can form on the end of continents but eventually form ocean basins. Divergent boundaries within continents initially produce rifts which produce rift valleys. Therefore, most active divergent plate boundaries are between oceanic plates and are often called mid-oceanic ridges. Divergent boundaries also form volcanic islands which occur when the plates move apart to produce gaps which molten lava rises to fill. Thus creating a shield volcano which would eventually build up to become a volcanic island.