Download Plates on the Move

Plates on the Move
Guide to plate movement
There are three types of plate
movement
1. Divergent
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Also known as seafloor
spreading
Plates are separating from
each other as a new land
mass forms
This is seen at mid-ocean
ridges and rifts
Plate separation is a slow
process. For example,
divergence along the Mid
Atlantic ridge causes the
Atlantic Ocean to widen at
only about 2 centimeters per
year.
Picture from www.geology.com
Author Hobart M. King
The Great Rift Valley- Africa
Rift valley
• http://www.youtube.com/watch?v=w7Y2R4K
Bwvo
2. Convergent
• Two continental plates
collide. & crumple the
edges of the plates &
form mountains.
•
We can see the end result of the
collision between the Indian &
Eurasian plates which are the
Himalayan Mountains.
Picture from www.geology.com Author Hobart M. King
Picture from USGS
Convergent Boundaries
1. Two plates come together.
2. The denser plate will sink.
3. Oceanic plates are ALWAYS denser than
continental plates.
4. If two oceanic plates come together, the
denser one will sink.
5. If an oceanic plate and a continental plate
collide, the oceanic plate will sink and the
area will be a subduction zone.
6. When two continental plates collide,
mountains form. Neither plate will sink.
7. Faults are a break in earth’s crust.
Convergent- Himalayan Mtns.
Subduction
• When an oceanic plate goes
underneath or is subducted under a
continental plate it is called
subduction.
• This forms a trench, or deep
valley, where the plates meet.
• An example of a subduction zone is
the Marianas Trench where the
Pacific Plate is subducting under
the Eurasian Plate.
• Subduction is another type of a
convergent plate movement.
Picture from www.geology.com Author Hobart M. King
Subduction and the mantle
3. Transform
• Two plates slide past
each other
– Example: San Andreas
Fault in California
Picture from www.geology.com
Author Hobart M. King
Transform- San Andreas Fault
Fault Lines, stress and earthquakes
Fault Lines and Earthquakes
Divergent
Convergent
Transform