tectonics 1.4 Flashcards
what is a divergent plate boundary?
where two plates move apart
example of divergent plate boundaries
oo divergence plate boundary between north american plate and eurasian plate
cc divergence plate boundary between nubian plate and somallian plate
what is a convergent plate boundary
plates move towards each other
example of convergent plate boundary
oo convergent plate boundary between philippine plate and pacific plate
cc convergent plate boundary between eurasian plate and indo-australia plate
oc convergent plate boundary between nazca plate and south american plate.
what is a transform plate boundary
2 plates slide past each other
example of transform plate boundary
san andreas fault line where pacific plate slid past north american plate
what happens at the oo divergent plate boundary
-2 oceanic plates move apart
decrease in overlying pressure causes parts of the underlying mantle to melt and thus forming magma
-magma then rises through the weak areas in the crust to the earth’s surface and fills gaps caused by seafloor spreading
-the lava cools and solidifies into basaltic rocks which then make up a new oceanic crust
what are the landforms formed by oo divergent plate boundaries
mid ocean ridges
volcanoes
underwater volcanoes
volcanic islands
rift systems
earthquakes
examples of oo divergent plate boundaries
north american plate and eurasian plate move apart to form the mid atlantic ridge and at the centre lies the great rift valley with steep sides
magma rises through the weak areas in the crust to the surface to form underwater volcanoes
volacnoes may break the surface after many eruptions and form volcanic islands for example. surtsey in iceland. Due to tensions and stress in ebtween the plate movemnts, there will also be earthquackes.
what happens at cc divergent plate boundaries
2 continental plates move apart
-rocks eventually fracture to form parallel faults
-rock between these faults collapse to form deep rift valleys with steep sides
-as plates move apart, the decrease in overlying pressure causes parts of the underlying mantle to melt , forming magma
-the magma rises through weak areas in the crust to the earth’s surface and forms volcanoes
-earthquakes also occur here due to the tension in between the plates when movement occurs.
examples of cc divergent plate boundaries
nubian plate pulls apart from somallian plate
which then forms the great rift valley
and examples of volacnoes formed by this is mount kilimanjaro and mount kenya
what happens at oo convergent plate boundaries
-2 oceanic plates collide
-denser plate subducts beneath other plate
-forms a deep depression, oceanic trench
-subducting plate sinks into the mantle and high pressure foces water out of the oceanic crust and lowers the melting point of overlying mantle.
-mantle melts into magma and rises through weak areas in the crust to the earth’s surface to form a chain of volcanoes known as volcanic islands
friction along subducting oceanic plates also causes earthquakes
example of oo convergent plate boundaries
pacific plate subducts beneath philippine plate and forms teh mariana trench and volcanic island, mariana island.
Island near mariana trench, guam experiences earthquakes
land forms formed in oo convergent plate
oceanic trench
volcanoes
volcanic islands
earthquakes.
what happens in cc convergent plate boundaries
2 continental plates collide
-no subduction since plates are too buoyant to subduct
-large amounts of pressure causes rocks to be uplifted and buckled to form fold mountains
-friction along convergent plate boundary also causes earthquakes
-magma does not rise up thus no volcanos
