Plate Tectonics Flashcards
Lithosphere
the rigid outer part of the earth, consisting of the crust and upper mantle
asthenosphere
The asthenosphere is the highly viscous, mechanically weak and ductilely deforming region of the upper mantle of the Earth. It lies below the lithosphere, at depths between approximately 80 and 200 km below the surfac
Mesosphere
the region of the earth’s atmosphere above the stratosphere and below the thermosphere, between about 30 and 50 miles
Inner Core
Earths most inner part
Outer Core
fluid layer about 2,300 km thick and composed iron and nickel
Seismic Waves
a wave energy that travels through the Earth and away from an earthquake in all directions
Oceanic Crust
the relatively thin part of the earth’s crust that 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 ratio of the mass of a substance to the volume of the substance
Alfred Wegener
German geophysicist who proposed the theory of continental drift
Continental Drift
the hypothesis that states that the continents once formed a single landmass, broke up and drifted to their present locations
Convergent Boundary
the boundary formed by the collision of two lithospheric plates
Divergent Boundary
the boundary between two tectonic plates that are moving away from each other
Transform Boundary
the boundary between tectonic plates that are sliding past each other horizontally
Sea-floor Spreading
the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies
Pangaea
a hypothetical supercontinent that included all current land masses, believed to have been in existence before the continents broke apart during the Triassic and Jurassic Periods.
Laurasia
The supercontinent of the Northern Hemisphere that, according to the theory of plate tectonics, broke up into North America, Greenland, Europe, and Asia except for the Indian subcontinent.
Gondwana
A vast continental area believed to have existed in the southern hemisphere and to have resulted from the break-up of Pangaea in Mesozoic times. It comprised present-day Arabia, Africa, South America, Antarctica, Australia, and the peninsula of India.
Mesosaurus
an extinct small aquatic reptile of the early Permian period, with an elongated body, flattened tail, and a long narrow snout with numerous needle-like teeth.
Glossopteris
“tongue”, because the leaves were tongue-shaped, and pteris, Greek for fern or feathery) is the largest and best-known genus of the extinct order of seed ferns known as Glossopteridales
