Transcript 5) Types of Boundaries

Types of Plate Boundaries
Geology 12
Types of Boundaries
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Convergent- area where opposing plates
smash together: Ex.- west coast of North
America
Divergent- Area where plates are moving
apart and spreading: Ex Mid-Atlantic rift
Transform- area where two plates are
sliding past one another in opposite
directions: Ex- San Andreas Fault
Divergent
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The lithosphere) is pulled apart, it
typically breaks along parallel
faults.
The block between the faults
cracks and drops down into the
soft, plastic interior (the
asthenosphere).
The sinking of the block forms a
central valley called a rift. Magma
(liquid rock) seeps upward to fill
the cracks.
New crust is formed along the
boundary.
Earthquakes occur along the
faults, and volcanoes form where
the magma reaches the surface.
Divergent Zones
Convergent Boundary
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Collisions are very slow and last
millions of years.
The edge of the continental plate
has folded into a huge mountain
range
The edge of the oceanic plate has
bent downward and dug deep into
the Earth and melts
The melted rock rises up through
the continental plate, causing
more earthquakes and forming
volcanic eruptions where it finally
reaches the surface.
An oceanic trench is a consistent
feature.
Most dangerous place to live
Transform Boundaries
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Plates on either side of a
transform boundary are merely
sliding past each other and not
tearing or crunching each other
Transform boundaries lack the
spectacular features found at
convergent and divergent
boundaries.
Transform boundaries are
marked in some places by
linear valleys along the
boundary where rock has been
ground up by the sliding.
Break-up of Pangaea- 210 million years
ago *NS at one point had a transform
fault and the province was splitting up.
Cobiquid-Chedabucto Fault – N.S.