Plate Tectonics Flashcards
Continental Drift
The hypothesis that states that the continents once formed a single landmass, broke up, a drifted to their present locations.
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.
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.
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.
Plate tectonics
The theory that explains how large pieces of the lithosphere, called 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 the 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.
Convergent boundary
The boundary between tectonic plates that are colliding.
Transform boundary
The boundary between tectonic plates that are sliding past each other horizontally.
Rifting
The process by which Earth’s crust 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 from and break apart over millions of years.
Pangaea
The supercontinent that formed 300 million years ago and that began to break up beginning 250 million years ago,
Panthalassa
The single, large ocean that covered Earth’s surface during the time the supercontinent Pangaea existed.
