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The Crust and Lithosphere Introduction The Earth's tectonic plates constitute the lithosphere so no proper understanding of plate tectonics can be achieved without reference to the lithosphere, and this requires an understanding of its essential difference from the crust. There are incorrect uses of both terms in text books - particularly common is the use of 'crustal', as opposed to 'lithospheric' plates - and these have contributed to widespread confusion and misunderstanding.
Search for:. Reading: The Lithosphere and Asthenosphere Can you think of a solid that can flow? Did you have an idea for improving this content? Licenses and Attributions. CC licensed content, Shared previously. But it is important to learn to differentiate between the two. The difference between Lithosphere and Asthenosphere is that the varieties of elements found on the lithosphere are larger than that in the asthenosphere. The lithosphere consists of 80 elements and mineral types whereas asthenosphere mainly contains iron-magnesium silicate.
This is the layer where the tectonic plates lie that are the cause of earthquakes, tsunamis and volcanic eruptions. The asthenosphere is the layer below the lithosphere. They are rather semi-fluid and allows the movement of their half molten rocks. The lithosphere is the uppermost layer of the Earth. The crust makes up the upper portion of the lithosphere. It is made up of lighter materials than the mantle and core, comprising mainly mafic and felsic rocks like granite.
While it is the thinnest layer of the Earth at only 60 to 70 kilometers thick, it makes up the majority of the lithosphere and is the portion of the Earth that supports life. The crust surface is shaped by characteristics of the lithosphere that cause formations like mountains and fault lines. The part of the crust that makes up continents is formed of lighter minerals than the part of the crust that makes up the oceanic floor.
The lithosphere, unlike the layers of the Earth, is defined not by composition but by behavior. The lithosphere is cold, relative to the fluid asthenosphere at least, and solid. It floats freely on top of the liquid magma of the upper mantle and is divided into discrete sections known as tectonic plates. The thickness of the lithosphere can be variable, with older portions being thicker, but tends to average a height of kilometers.
Young portions of the lithosphere are formed by the downward movement and melting of one tectonic plate beneath another at a boundary known as a subduction zone.
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