plates moving towards each other, 3 possible scenarios (CC, OO, CO)
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Divergent boundary
plates moving apart, __formation of new crust created at rift valleys/mid-ocean ridges__, mild volcanic eruptions & shallow earthquakes
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CC convergent boundary
plates moving towards each other, __formation of collisional mt. ranges__, common earthquakes, overriding of C plates, no volcanoes or subduction of C crust
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CO convergent boundary
plates moving towards each other, __formation of mt. ranges on the C side, trenches on the O side__, explosive volcanoes & earthquakes
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OO convergent boundary
plates moving towards each other, __formation of volcanic island arcs & trenches__, explosive volcanoes & earthquakes, subduction of which crust is denser (older)
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lithosphere
Rigid layer made up of crust & upper mantle
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asthenosphere
Plastic layer made up of upper mantle below lithosphere
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mesosphere
More rigid than asthenosphere but still flows
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outer core
Liquid, flows
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inner core
Solid, doesn’t flow
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Moho
Boundary between crust and mantle
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Pillow basalt
Created from basaltic lava erupting underwater that cools quickly
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slab pull
occurs bc cold slabs of oceanic lithosphere are denser than warm asthenosphere, so they sink
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granite
Rock that makes up continental crust
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oceanic crust
Crust above ocean
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peridotite
Rock that makes up the mantle
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hot spot
plumes of mantle rising up that are random
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tectonic plate
massive slab of lithosphere
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Harry hess
Studied the seafloor, proposed that mid-Atlantic ridge was spreading center
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Alfred wegener
Came up with the continental drift hypothesis
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reverse polarity
When the south pole is the magnetic pole
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ridge push
results from elevated position of oceanic ridge, causes slabs of lithosphere to slide down ridge
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rift valley
Forms from upwarping of the lithosphere.
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seafloor spreading
As plates move apart, asthenosphere rises to surface & melts (lower pressure), once it cools, new ocean crust is formed. Continents move apart, powered by convection
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subduction
The sinking of lithosphere into the asthenosphere, where plates converge
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transform boundary
* plates moving past each other horizontally, __formation of faults__, no up or down motion of plates, shallow earthquakes, no subduction or volcanism
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trench
Forms at convergent OC boundaries
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volcanic island arc
Forms at convergent OO boundaries
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plate tectonics theory
Scientific revolution that unfolded between 1915 and 1970, states the Earth’s surface is broken into rigid tectonic plates that are in constant motion
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Pangea
Supercontinent, or single continent, that existed 200-300 mil ya
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continental drift hypothesis
The continents were once joined together in a single large landmass called Pangea
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pole reversal
Every so often, the magnetic poles of Earth reverse, so that the magnetic north pole is now located over the geographic south pole
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paleomagnetism
Earth is a magnet w/ magnetic fields at poles, every 300,000 years, magnetic poles reverse, as seafloor spreads, it creates bands of equal polarity moving away from each other at equal speeds
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Marie tharp and bruce heezen
Made first map of North Atlantic in 1957, discovered huge mt. ranges in the middle of both oceans, contributed to plate tectonics theory
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Frederick vine and drummond matthews
Interpreted magnetic stripes on seafloor as products of steady creation of new ocean crust over geologic time
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normal polarity
When the magnetic poles and geographical poles are lined up
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failed rift
Rift that stopped formation into sea and ocean ridge for an unknown reason
Studied by 6 people
