There are three types of convergence:
is a process through which oceanic crust is
destroyed by going back into the mantle. The
word subduction comes from the Latin "sub,"
which means "under," and "ducere,"
which means "to lead." Typically,
subduction leads to the formation of a trench.Oceanic
crust, though thinner than continental crust,
is denser (i.e., heavier per unit volume). Oceanic
crust is mostly composed of a lava called basalt.
The continents, thicker than the ocean crust,
are dominated by the igneous rock granite. Granite
is less dense than basalt. It is also lighter
in color, usually indicating that it has less
iron and magnesium in its constituent minerals.