continental drift
the hypothesis that a single large landmass broke up into smaller landmasses to form the continents, which then drifted to their present locations
mid-ocean ridge
a long, undersea mountain chain that has a steep, narrow valley at its center, forms as magma rises from the athenosphere, and that creates new oceanic lithosphere (sea floor) as tectonic plates move apart
sea-floor spreading
the process by which new oceanic lithosphere (sea floor) forms when magma rises to Earth's surface at mid-ocean ridges and solidifies, as older, existing sea floor moves away from the ridge
paleomagnetism
the study of the allignment 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
plate tectonics
the theory that explains how large pieces of the lithosphere (plates) move and change shape
lithosphere
the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle;
asthenosphere
the solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
divergent boundary
the boundary between tectonic plates that are moving away from each other; dividing
transform boundary
the boundary between tectonic plates that are sliding past each other horizontally
convergent boundary
the boundary between tectonic plates that are colliding
rifting
the process by which Earth's crst breaks apart; can occur within continental crust or oceanic crust
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
supercontinent cycle
the process by which supercontinents form and break apart over millions of years
Pangea
the supercontinent that formed 300 milliion years ago and began to break up 200 milliion years ago
Panthalassa
the single, large ocean that covered Earth's surface during the time the supercontinent Pangea existed
deformation
the bending, tilting, and breaking of Earth's crust; the change in the shape of rock in response to stress
isostasy
a condition of gravitational and buoyant equilibrium between Earth's lithosphere and athenosphere
stress
the amount of force per unit are that acts on a rock
strain
any change in a rock's shape or volume caused by stress
fold
a form of ductile strain in which rock layer bend, usuallt as a result of compression
fault
a break in a body of rock along which one block slides relative to another; a form of brittle strain
mountain range
a series of mountains that are closely related in orientation, age, and model of formation
folded mountain
a mountain that forms when rock layers are squeezed together and uplifted
fault-block mountain
a mountain that forms where faulting breaks Earth's crust into large blocks, which causes some blocks to drop down relative to other blocks
dome mountain
a circular or elliptical, almost symmetrical elevation or structure in which the stratified rock slopes downward gently from the central point of folding
crust
the thin and solid outermost layer of the Earth above the mantle
mantle
the layer of rock between Earth's crust and core
core
the central part of the Earth below the mantle