What forms along divergent and convergent boundaries?
Along divergent boundaries, the crust separates allowing hot magma from the mantle to rise to the surface. This rising magma often causes volcanos. Many of the volcanos are called deep sea vents because the magma erupts underneath the surface of the water. These undersea volcanos can reach the surface forming chains of islands. Iceland, and south pacific chains are examples
Convergent boundaries can also form volcanos. Where an ocean plate collides with a continental plate volcano's are formed. The Pacific ring of fire is an example. The volcanos are formed as the crust of the ocean plate is pushed under the continental plate. The sedimentary layers of the oceanic plate are melted as the crust is pushed down into magma. The melted rocks are under pressure and push toward the surface. If the magma reaches the surface a volcano is formed.