Plate Tectonics 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 in altitude.
Inner Core
Earth’s innermost part. It is primarily a solid ball with a radius of about 1,220 kilometres, which is about 70% of the Moon’s radius.
Outer Core
Earth is a fluid layer about 2,400 km thick and composed of mostly iron and nickel that lies above Earth’s solid inner core and below its mantle.
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 polar researcher, geophysicist and meteorologist.
Continental Drift
the gradual movement of the continents across the earth’s surface through geological time.
Convergent Boundary
areas on Earth where two or more lithospheric plates collide.
Divergent Boundary
linear feature that exists between two tectonic plates that are moving away from each other.
Transform Boundary
plate boundary where the motion is predominantly horizontal.
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.
