Background Info:
The direct collision of two plates
forms a type of plate boundary
known as a convergent boundary.
When a plate with oceanic crust at
its leading edge meets a plate with
continental crust at its edge a
condition called a subduction zone
results. Also known as an
active-margin continental shelf, this
condition is characteristic of the
Pacific basin, where the continental
shelves tend to be narrower and
more varied than in the Atlantic
basin. Because oceanic crust is
denser than continental crust, when
the two meet at a subduction zone,
the oceanic crust is forced under,
often resulting in continental
mountain ranges. Scientists think
that as the oceanic crust is
subducted it melts, becoming part
of the mantle material. Volcanic
mountains are regularly found in the
ranges formed along subduction
zones. The Chile Trench is an
example of a trench at the edge of
a continental shelf. It results from
the subduction of the Nazca plate
beneath the American plate.
|
