Divergent
A divergent boundary is exactly what it sounds like, a
plate boundary where the plates diverge. Plates in a
divergent boundary undergo a tensional tectonic force known
as tension stress ("Types of Plate Boundaries"). This is a
puling force that rips apart the plates at a boundary. The
central block at the spread can drop down and form a
geologic characteristic known as a graben. Volcanism is
quite common along the rift's faults causing even more
spreading to occur. Today's active divergent boundaries are
midoceanic ridges. These sea floor spreading centers create
underwater mountain ranges formed from the magma present at
the spread.