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28 terms

Earth's Layers Plate Tectonics

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crust
thin and solid outer layer of the Earth.
mantle
the layer of rock between the Earth's crust and core.
core
the central part of the Earth below the mantle.
lithosphere
the solid, outer layer of the Earth that consists of the crust and the rigid upper part of the mantle.
asthnosphere
the soft layer of the mantle on which the tectonic plates move. Convection currents occur in this layer.
tectonic plates
a block of lithosphere that consist of the crust and the ridgid, outer most part of the mantle.
continental drift
the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to the present locations.
sea-floor spreading
the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.
plate tectonics
the theory that explains how large pieces of the Earth's outer most layer called " tectonics plates" move and change shape.
convergent boundary
the boundary formed by the collision of two lithospheric plates.
divergent boundary
the boundary between two tectonic plates that are moving away from each other.
transform boundary
the boundary between tectonic plates that are sliding past each other horizontally.
compression
stress that occurs when forces act or squeeze an object. Compression happens at convergent boundaries.
tension
stress that occurs when forces act to stretch a boundary. This happens at divergent boundaries.
folding
the bending of a rock layer due to stress.
fault
breaking in a body or rock along which one block slides relative to another one.
uplift
the rising of regions of the Earth's crust to higher elevations.
subsidence
the sinking of a region of the Earth's crust to lower elevations.
subduction zone
the region where an oceanic plate sinks down into the asthenosphere at a convergent boundary, usually between continental and oceanic plates
Pangea
large supercontinent that existed 250 million years ago
convection current
a current caused by the rising of heated fluid and sinking of cooled fluid
sea-floor spreading
The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
mid-ocean ridge
an undersea mountain chain where new ocean floor is produced; a divergent plate boundary. This is the longest mountain chain in the world.
seismic wave
a vibration caused by rocks moving and breaking along faults
inner core
a dense sphere of solid iron and nickel at the center of Earth
outer core
the liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core
rift valley
a long, narrow valley that forms as tectonic plates seperate.
deep ocean trench
a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle