Chapter 02 Vocab Flashcards
absolute plate velocity
The movement of a plate relative to a fixed point in the mantle.
abyssal plain
A broad, relatively flat region of the ocean that lies at least 4.5 km below sea level.
accretionary prism
A wedge-shaped mass of sediment and rock scraped off the top of a downgoing plate and accreted onto the overriding plate at a convergent plate margin.
active margin
A continental margin that coincides with a plate boundary.
apparent polar-wander path
A path on the globe along which a magnetic pole appears to have wandered over time; in fact, the continents drift, while the magnetic pole stays fairly fixed.
asthenosphere
The layer of the mantle that lies between 100-150 km and 350 km deep; the asthenosphere is relatively soft and can flow when acted on by force.
bathymetry
Variation in depth.
black smoke
The cloud of suspended minerals formed where hot water spews out of a vent along a mid-ocean ridge; the dissolved sulfide components of the hot water instantly precipitate when the water mixes with seawater and cools.
collision
The process of two buoyant pieces of lithosphere converging and squashing together.
continental drift
The idea that continents have moved and are still moving slowly across the Earth’s surface.
continental rift
A linear belt along which continental lithosphere stretches and pulls apart.
continental shelf
A broad, shallowly submerged fringe of a continent; ocean-water depth over the continental shelf is generally less than 200 meters; the widest continental shelves occur over passive margins.
convergent boundary
A boundary at which two plates move toward each other so that one plate sinks (subducts) beneath the other; only oceanic lithosphere can subduct.
divergent boundary
A boundary at which two lithosphere plates move apart from each other; they are marked by mid-ocean ridges.
fracture zone
A narrow band of vertical fractures in the ocean floor; fracture zones lie roughly at right angles to a mid-ocean ridge, and the actively slipping part of a fracture zone is a transform fault.
global positioning system (GPS)
A satellite system people can use to measure rates of movement of the Earth’s crust relative to one another, or simply to locate their position on the Earth’s surface.
hot spot
A location at the base of the lithosphere, at the top of a mantle plume, where temperatures can cause melting.
hot-spot track
A chain of now-dead volcanoes transported off the hot spot by the movement of a lithosphere plate.