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31 terms

Ch 10 - Plate Tectonics

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tectonic plates
blocks of rock that ride on top of the asthenosphere
island arc
a chain of volcanic islands that forms near the collision of two oceanic plates
terrane
a piece of lithosphere that has a unique geologic history and that may be part of a larger piece of lithosphere, such as a continent
Pacific Ring of Fire
a zone of active volcanoes that encircles the Pacific Ocean
convergent boundary
the boundary between tectonic plates that are colliding
divergent boundary
the boundary between tectonic plates that are moving away from each other
continental drift
the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
Laurasia
the large northern landmass that separated after the break up of Pangaea including North America, Europe, and Asia
Gondwanaland
the large southern landmass that separated after the break up of Pangaea including South America, Africa, India, Antarctica, and Australia
rifting
the process by which Earth's crust breaks apart; can occur within continental crust or oceanic crust.
sea-floor spreading
the process by which new oceanic lithosphere (sea floor) forms as magma rises to Earth's surface and solidifies at a mid-ocean ridge
Panthalassa
the single, large ocean that covered Earth's surface during the time the supercontinent Pangaea existed
paleomagnetism
the study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock acquires during formation
Pangaea
the supercontinent that formed 300 million years ago and that began to break up beginning 250 million years ago
plate tectonics
the theory that explains how large pieces of the lithosphere, called plates, move and change shape
deep-ocean trench
a deep valley that forms along the boundary where an ocean plate subducts
transform boundary
a boundary between tectonic plates that are sliding past each other horizontally
mid-ocean ridge
a long, undersea mountain chain that has a steep, narrow valley at its center, that forms as magma rises from the asthenosphere, and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart
rift valley
a narrow valley that forms where the plates separate
convection
the movement of heated material due to differences in density created by temperature differences
supercontinent cycle
The process by which supercontinents form and break apart over millions of years
geomagnetic reversal time scale
alternating periods of normal and reversed polarity in oceanic crust
subduction zone
the region along a plate boundary where one plate moves underneath another
lithosphere
The solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle
asthenosphere
The solid, plastic-like layer of the mantle that flows very slowly, which allows tectonic plates to move on top of it
rift
a crack in Earth's crust
magma
molten rock inside the Earth
craton
a large area of stable rock that are older than 540 million years
accretion
the process in which a terrane becomes part of a continent
seamount
an underwater mountain
atoll
a small coral island