33 terms

Plate Tectonics 2

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continental drift
hypothesis that Earth's continents had once been joined as a single landmass that broke apart and sent the continents adrift
Pangea
supercontinent that broke apart about 200 mya
magnetometer
a device that can detect small changes in magnetic fields
magnetic reversal
happens when the flow in the outer core changes and Earth's magnetic field changes direction
seafloor spreading
theory that explains how new oceanic crust is formed at ocean ridges, slowly moved away from ocean rides, and destroyed at deep sea trenches
tectonic plates
huge pieces of crust and rigid upper mantle that fit together at their edges to cover Earth's surface
divergent boundaries
regions where 2 tectonic plates are moving apart. New crust formed here
rift valley
when continental crust begins to separate, the stretched crust forms a long, narrow depression. Formed at divergent plate boundary
convergent boundaries
two tectonic plates are moving toward each other. Old crust recycled (destroyed) here.
subduction
when two plates collide, the denser plate descends below the less-dense plate. Occurs at convergent plate boundary.
transform boundary
a region where two plates slide horizontally past each other. Crust is not added or destroyed here. There are no volcanoes or mountains. Example: San Andreas Fault
topography
the variation in elevations of the crust
orogeny
all processes that form mountain ranges
uplifted mountains
formed when large regions of Earth have been slowly forced upward as a unit. Formed at convergent boundary.
plateau
relatively flat-topped area of uplift
land bridge
hypothesis to explain how fossil evidence was found on continents separated by oceans
lithosphere
brittle and made of crust and some upper mantle it makes up the tectonic plates
asthenosphere
weak, plastic made up of the upper mantle
mesosphere
made up of the rest of the upper and the lower mantle
outer core
made up of liquid iron
inner core
made up of solid iron and nickel
mid-ocean ridge
mountains and volcanoes that form at a divergent plate boundary. New crust is formed here.
ocean basin
when a divergent boundary occurs on land
Red Sea
example of an inactive rift valley formed at a divergent boundary
continental crust
thick but relatively less dense
oceanic crust
thin but relatively more dense
trench
formed at an Oceanic to Continental or Oceanic to Oceanic convergent boundary
volcanic mountain arc
formed at an Oceanic to Continental convergent boundary. Example is Andes mountain range
volcanic island arc
formed at an Oceanic to Oceanic convergent boundary. Example is Japan
Continental to Continental Convergent Boundary
No subduction, volcanoes or trenches. Can have earthquakes and create mountains like the Himalaya's
Oceanic to Oceanic Convergent Boundary
Can form oceanic trench, volcanic island arc (Japan) or earthquake.
Oceanic to Continental Convergent Boundary
Can form oceanic trench, volcanic mountain arc (Andes mountains), or earthquakes
convection
process when hotter material (less dense) rises and colder material (more dense) sinks. Cause for plate movement.