Plate Tectonic Flashcards
Lithosphere
the rigid outer part of the earth, consisting of the crust and upper mantle.
Asthenosphere
the upper layer of the earth’s mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.
Mesosphere
the region of the earth’s atmosphere above the stratosphere and below the thermosphere, between about 30 and 50 miles (50 and 80 km) in altitude.
Inner Core
Earth’s inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km, which is about 20% of Earth’s radius or 70% of the Moon’s radius.
Outer Core
The outer core is the third layer of the Earth. It is the only liquid layer, and is mainly made up of the metals iron and nickel, as well as small amounts of other substances.
Seismic Waves
an elastic wave in the earth produced by an earthquake or other means.
Oceanic Crust
the relatively thin part of the earth’s crust which underlies the ocean basins. It is geologically young compared with the continental crust and consists of basaltic rock overlain by sediments.
Continental Crust
the relatively thick part of the earth’s crust that forms the large landmasses. It is generally older and more complex than the oceanic crust.
Density
the degree of compactness of a substance.
Alfred Wegener
German meteorologist and geophysicist Alfred Wegener was the first person to formulate a complete statement of the continental drift hypothesis.
Continental Drift
Continental drift was a theory that explained how continents shift position on Earth’s surface.
Convergent Boundary
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide.
Divergent Boundary
A divergent boundary occurs when two tectonic plates move away from each other.
Transform Boundary
Transform boundaries are places where plates slide sideways past each other.
Sea-floor Spreading
the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.
