Plate Tectonics Flashcards
Divergent Boundary
A boundary along which two tectonic plates move apart, characterized by either a mid-ocean ridge or a continental rift valley.
Transform Boundary
A boundary along which two tectonic plates scrape past each other, and crust is neither formed nor destroyed.
Continental Drift
The hypothesis that Earth’s continents move on Earth’s surface.
Asthenosphere
The layer in Earth’s upper mantle and directly under the lithosphere in which rock is soft and weak because it is close to melting.
Theory of Plate Tectonics
A theory stating that Earth’s lithosphere is broken into huge plates that move and change in size over time.
Mid-Ocean Ridges
A long line of sea-floor mountains where new ocean crust is formed by volcanic activity along a divergent boundary.
Convergent Boundary
A boundary along which two tectonic plates push together, characterized either by subduction or a continental collision.
Rift Valley
A deep valley formed as tectonic plates move apart, such as along a mid-ocean ridge.
Lithosphere
The layer of Earth made up of the crust and the rigid rock of the upper mantle, averaging about 40 kilometers thick and broken into tectonic plates.
Convection Currents
A circulation pattern in which material is heated and rises in one area, then cools and sinks in another area, flowing in a continuous loop.
Hot Spot
An area where a column of hot material rises from the deep within a planet’s mantle and heats the lithosphere above it, often causing volcanic activity at the surface.
Subduction
The process by which an oceanic tectonic plate sinks under another plate into Earth’s mantle.
