Environmental Engineering Reference
In-Depth Information
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Transform plate boundaries:
Transform plate boundaries are commonly known as
faults
and are found
on the ocean floor. At the zone of transform plate boundaries, tectonic plates slide in a sideways motion
past one another. As they slide and stick, friction and energy build up. When the pressure is eventually
relieved, earthquakes can occur at these boundaries. Examples of transform boundaries exposed on land
include the San Andreas Fault in California and the Alpine Fault in New Zealand.
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Divergent plate boundaries:
When two or more plates pull away from one another, divergent plate
boundaries are created. An example of a divergent boundary is the movement of plates at the mid-ocean
ridge, where the ocean becomes wider as plates diverge. The East Africa Rift Valley is an example.
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Convergent plate boundaries:
When two plates move toward one another, a convergent plate boundary
is created as one plate dives under the other. With this collision, different events can follow, depending
on the type of crust involved. Examples of convergent boundaries include the Andes Mountains in South
America, the Cascade Mountains in the northwestern United States, and the Marianas Trench in the Pa-
cific Ocean.
Oceanic and continental plates
Oceanic and continental plates in collision lead to
subduction.
Subduction of oceanic plates at plate boundar-
ies is the cause of continental crust being older than oceanic crust. The denser oceanic plate is pushed below
the lighter continental plate. When the crust is compacted and pushed up during the collision of two continental
plates, mountain ranges are formed. This motion created the Himalaya Mountains, which are still growing
