• What is the lithosphere?

    Nadezhda Kazantseva
    Nadezhda Kazantseva
    February 4, 2013
    What is the lithosphere?

    The lithosphere - in general terms, is the top layer of the earth's surface, consisting of three layers. The opinions of scientists regarding the precise definition of the concept and composition of the lithosphere are somewhat scattered. Yet what is the lithosphere? What is composed and what layers it consists of, we will now consider.

    The lithosphere (Earth's crust) covers the entire surface area of ​​the Earth, as well as the upper layer of its mantle (the part of the Earth located below the crust but above the core). But despite this, the weight of the earth's crust is only one percent of the total mass of the planet. Most of the lithosphere consists of solid rocks, but on the border with the mantle the rocks have a more plastic consistency. The structure of the earth's crust is represented by folded and stable platforms.

    The thickness of the crust at different levels of the earth's surface ranges from 25 to 200 km, and at the bottom of the ocean from 5 to 100 km. Geographic encyclopedias and dictionaries give a more complete concept of what the lithosphere is. The definition is as follows:

    The lithosphere is the outer sphere (shell) of the Earth, bounded by the atmosphere and hydrosphere.The lithosphere is folded in three layers: the first is sedimentary, the second is granite and the lower is basalt:

    • The sedimentary layer is formed as a result of the re-formation of weathering products, chemical and other destruction of rocks, sedimentation of water and decomposition products. At the bottom of the ocean, it is formed mainly by washing out sedimentary rocks from the surface of continents by rivers.
    • The granite layer is composed of metamorphic and igneous rocks, occupies an intermediate position between the sedimentary and basalt layers of the earth's crust, but is completely absent on the ocean floor. In the granite layer, the movement of tectonic plates is gaining speed of up to five to six kilometers per second.
    • The basalt layer is the lower layer of the earth's crust with a high content of iron and magmatic rock Gabbro, consisting of plagioclase, igneous rocks and colored minerals. In this layer, the movement of tectonic plates can reach speeds of up to 7 km / s.

    The bark of the ocean floor and continents is different: the granite layer is completely absent under the water. This, to a greater extent, is caused by the melting of rocks. In this connection, the layer of the lithosphere of the underwater surface is much thinner.

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