20 terms

Unit 6.2: Plate Tectonics

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Lithosphere
the top layer of the Earth which consists of the crust and the uppermost (rigid/brittle) portion of the mantle; is broken into large pieces called plates
Asthenosphere
a zone in Earth's mantle where heat and pressure cause rock to be soft and fluid; tectonic plates move on top of this layer (convection cells move like conveyor belts through this zone)
Continental Drift
a hypothesis, proposed by Alfred Wegener, that the continents move around on Earth's surface (and were once joined in one large landmass)
Pangea
an ancient supercontinent composed of the early forms of all the modern continents
Tectonic Plates
large pieces of Earth's brittle outermost layer that fit together like pieces of a puzzle; the pieces move and interact at the boundaries to create many of the landforms on Earth
Convection Current
a current of matter moving in a roughly circular path due to the heating and cooling of material as it gets closer to/further away from the core; responsible for the motion of tectonic plates
Fault
any fracture in the Earth's surface; all plate boundaries
Convergent Boundary
a place where tectonic plates are coming together; create mountains or trenches (subduction zones)
Transform Boundary
a place where tectonic plates move past each other horizontally; create fault scars and offset
Divergent Boundary
a place where tectonic plates are moving away from one another; create rift valleys and ocean basins
Seafloor Spreading
the process by which new oceanic crust is formed at a divergent boundary that is beneath the ocean
Mid-Ocean Ridge
a mountain range on the ocean floor caused by volcanic activity along a divergent boundary
Magnetic Reversal
a change in Earth's magnetic poles; when the magnetic north pole reverses position with the magnetic south pole
Rift Valley
a low lying area resulting from a divergent boundary in continental lithosphere; can eventually open up to the ocean and create a new ocean basin
Subduction Zone
a place where one tectonic plate (usually a denser, thinner piece of oceanic lithosphere) sinks underneath another at a convergent boundary
Magma
molten rock beneath the surface of the Earth
Lava
molten rock that flows out onto the surface of the Earth from a volcano or other vent
Hot Spot
a place within Earth where increased thermal energy near the mantle/core boundary causes the production of magma and volcanic activity far from a plate boundary
Trench
long, steep, arcing valleys in the ocean floor caused by one plate sinking beneath another at a subduction zone
Ring of Fire
Area around the Pacific Ocean known for frequent earthquakes and volcanoes
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