plate tectionics Flashcards
Lithosphere
A lithosphere is the rigid, outermost shell of a terrestrial-type planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more
Asthenosphere
The asthenosphere is the highly viscous, mechanically weak, and ductile region of the upper mantle of Earth. It lies below the lithosphere, between approximately 80 and 200 km below the surface. The lithosphere–asthenosphere boundary is usually referred to as the LAB.
Mesosphere
The mesosphere is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases.
Inner Core
Earth’s inner core is the innermost geologic layer of 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. There are no samples of Earth’s core accessible for direct measurement, as there are for Earth’s mantle.
Outer Core
Earth’s outer core 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. Its outer boundary lies 2,890 km beneath Earth’s surface.
Seismic Waves
Seismic waves are waves of energy that travel through Earth’s layers, and are a result of earthquakes, volcanic eruptions, magma movement, large landslides and large man-made explosions that give out low-frequency acoustic energy.
Oceanic Crust
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust overlies the solidified and uppermost layer of the mantle.
Continental Crust
continental crust, the outermost layer of Earth’s lithosphere that makes up the planet’s continents and continental shelves and is formed near subduction zones at plate boundaries between continental and oceanic tectonic plates. The continental crust forms nearly all of Earth’s land surface.
Density
Density is the number of things—which could be people, animals, plants, or objects—in a certain area. To calculate density, you divide the number of objects by the measurement of the area. The population density of a country is the number of people in that country divided by the area in square kilometers or miles
Alfred Wegener
Alfred Lothar Wegener was a German climatologist, geologist, geophysicist, meteorologist, and polar researcher.
Continental Drift
Continental drift is the hypothesis that the Earth’s continents have moved over geologic time relative to each other, thus appearing to have “drifted” across the ocean bed. The speculation that continents might have ‘drifted’ was first put forward by Abraham Ortelius in 1596.
Convergent Boundary
A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone.
Divergent Boundary
A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth’s mantle to the surface, solidifying to create new oceanic crust. The Mid-Atlantic Ridge is an example of divergent plate boundaries.
Transform Boundary
A transform fault or transform boundary, sometimes called a strike-slip boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduction zone.
Sea-floor Spreading
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other. … The less-dense material rises, often forming a mountain or elevated area of the seafloor. Eventually, the crust cracks.
