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Read and learn for free about the following article: Mantle Convection and Plate and the vertical forces due to density difference are referred to as buoyancy forces. Mantle Convection and Interconnections Between Different Earth Systems. The mantle lies between Earth's dense, super-heated core and its The asthenosphere is much more ductile than either the lithosphere or lower mantle. the difference in ductility between the two layers of the upper mantle. This drawing shows the Earth's lithosphere (crust and upper mantle) on top of a somewhat fluid part of the mantle called the asthenosphere.
Beyond this lies the outer core, also iron-dominated but — in contrast to the inner core it surrounds — molten or liquid.
The mantle, the most extensive layer of the planet, lies above the outer core; mantle thickness averages about 1, miles. Sciencing Video Vault The Lithosphere The lithosphere encompasses the very top of the mantle above the asthenosphere as well as the overlying crust.
What is the difference between the mantle and asthenosphere? : geology
Oceanic crust is relatively thin and dense, dominated by basaltic rock rich in silica and magnesium. Continental crust is lighter and thicker, made up mainly of granitic rocks dominated by silica and aluminum. The crust extends some 2 to 6 miles beneath ocean basins and as far as 50 miles beneath major mountain belts on the continent before transitioning to the iron- and magnesium-rich peridotite of the upper mantle.
That boundary between crustal and mantle rocks is named for the scientist a meteorologist, actually who helped discover it: While heat spreads quickly in the asthenosphere by convection, the cooler, rigid rock of the lithosphere transfers heat much more slowly by conduction. Plate Tectonics The asthenosphere and lithosphere's physical properties help establish the fundamental forces that move and shape the features composing the surface of the Earth, described in the theory of plate tectonics.
The hot, flowing asthenosphere — which remains hot and flowing because of the convection of heat from the Earth's innards — provides a lubricating layer on which the rigid plates of the lithosphere can slide. The lithosphere varies in thickness but is typically a hundred or so kilometers thick.
It includes the upper mantle and both the continental and oceanic crust. These plates may move away from, move by, or collide with each other.
This process forms ocean basins, shifts continents, and pushes up mountains. Tectonic plates break apart and diverge where the mantle beneath is upwelling. In such regions mid-ocean ridges develop, and new lithosphere and crust form to replace the material that is moving away.
Where plates converge, usually where the mantle is downwelling, one plate is forced beneath another. When this involves plates with embedded continental crust, mountain belts such as the Alps and Himalayas form.
If the collision involves plates with oceanic crust, subduction zones form where one plate descends into the mantle beneath the other plate.
The Geological Society
Above these subduction zone chains of volcanoes and island arcs like the Aleutians, develop. Below the Aleutian island arc, at depths of to kilometers, water is forced out of the subducted Pacific plate. This water lowers the melting point of the overlying mantle, causing it to melt. The melting forms magma, which rises to feed the 55 currently active volcanoes that make up the island arc. California's San Andreas fault system is an example.
So mantle convection not only accounts for ocean basins, continents, and mountains, it is also the ultimate reason for nearly all earthquakes and volcanoes. The San Andreas is probably the best-known transform fault boundary.
In fact, the connected mid-ocean ridge system is in essence a 80, km long volcano. Over the course of several million years, all of the water in the world's oceans cycles through the oceanic crust at mid-ocean ridges. This is how the hydrothermal circulation influences ocean composition.
How about atmospheric and oceanic circulation?