Basaltic volcanism, which is responsible for the formation of Earth's oceanic crust, is also the dominant form of volcanism on Earth.
(Basaltic volcanism; is; responsible for the formation of Earth's oceanic crust) (Basaltic volcanism, which is responsible for the formation of Earth's oceanic crust; is also; the dominant form of volcanism on Earth)
Basaltic volcanism Basaltic volcanism, which is responsible for the formation of Earth's oceanic crust
is is also
responsible for the formation of Earth's oceanic crust
the dominant form of volcanism on Earth