Transcript How Plates Create

Trench
•
When two plates of oceanic crust collide, one
plate sinks beneath the other.
•
One of the plates is pushed beneath the
deep-sea trench down toward the mantle.
•
A deep-ocean trench may form where
oceanic crust sinks toward the mantle
beneath continental crust. Some of the
oceanic crust melts to form magma.
Volcanic Islands

Beneath the trench, the plate melts
and becomes magma.

The magma erupts to the surface
forming a row of volcanic islands.
Mid-Oceanic Ridge

Sea-floor spreading occurs as oceanic
plates pull apart along the mid-oceanic
ridge.

A mid-ocean ridge is a mountain range
that winds through Earth’s oceans.

Lava erupts through narrow cracks
along the ridge, adding new rock to the
ocean floor.
Rift Valley

A rift valley forms when two pieces of
continental crust pull apart.

Over millions of years, the rift valley
could widen and sink below sea level,
forming a new ocean.
Earthquakes

When two plates slide past each
other, moving slowly in opposite
directions, earthquakes can occur.
Mountains

If two plates carrying continental crust collide, neither plate
sinks beneath the other.

Instead, the plates slowly fold and pile on top of each
other, forming a mountain range.