Download Convergent boundary

What is the Theory of Plate Tectonics?
• It states that pieces of
Earth’s lithosphere are
in a slow, constant
motion, driven by
convection currents in
the mantle.
• As the plates move,
they collide, pull apart,
or grind past each
other, producing
spectacular changes in
Earth’s surface. These
changes include
volcanoes, mountain
ranges, and deep ocean
trenches.
http://w3.salemstate.edu/~lhanson/gls110/GLS110_BasicConcepts.htm
Plate Boundaries
• The places where these lithospheric plates come together are
called plate boundaries
• There are three types: divergent boundaries, convergent
boundaries, and transform boundaries.
• A different type of plate movement occurs along each type of
boundary.
What is a divergent boundary?
• Divergent Boundary: where two
plates move apart
What happens at divergent
boundaries?
• #1. If two oceanic plates
move apart, then a midocean ridge is formed.
EX: Atlantic Mid-Ocean
Ridge
• #2. If two continental
plates move apart, then a
rift valley is formed. EX:
Great Rift Valley in Africa
This happens because…
• Molten material fills in the space
left between the two plates to form
new land.
We can see this above water
in Iceland!
Hydrotherma vents along midocean ridges!
Smokers
Can things live in this superheated environment?
Complex
communities
fueled by the
chemicals
dissolved in
the vent fluids
Tubeworms, palmworms,
scale worms and limpets
thrive in warm, diffusely
flowing vent fluids issuing
from the black smoker
chimney "Finn" on the Juan
de Fuca Ridge
What is a convergent boundary?
• Convergent
boundary: place
where two plates
come together.
• The result is a
collision where the
density of the plate
determines what
happens.
http://www.divediscover.whoi.edu/images/tectonics-collide.jpg
Convergent Boundary #1
• If an oceanic plate
meets a continental
plate then the
oceanic plate is
subducted and
volcanoes are
formed.
• This happens
because the oceanic
plate is more dense.
Convergent Boundary #2
• If two continental
plates collide (equal
density), mountains
are created.
• EX: Himalayas
Convergent Boundary #3
• If two oceanic plates collide then the
plate that is more dense will subduct
into the mantle through a deep-ocean
trench.
What is a transform boundary?
• A boundary where
two plates grind past
each other without
the production or
destruction of
lithosphere.
• A fault is created. EX:
San Andreas Fault
• Notice subduction
zone…
When it comes to the Earth,
it’s like a rug…
http://rst.gsfc.nasa.gov/Sect2/Sect2_6.html
• Over millions of years, the forces of plate
movement can change a flat plain into
landforms such as anticlines and synclines,
folded mountains, fault-block mountains, and
plateaus.
Folding Earth’s Crust
• This results in
mountains and
plateaus. EX:
Colorado Plateau
Rockies were never volcanoes.
Divergent
Convergent
Transform