The Beautiful Planet Earth: The Earth Crust.

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This blog offers an exceptional discovery analizis the layers of our planet from the Earth's crust to the depths of hot mantle into the secret core of the planet. Also offers a look at what man kind will probably never reach, the more alien and hostile to the rocks, lava, and minerals below the earth's crust. While the crust is approximately 20 to 30 km deep in most places, humans have never traveled further, even so, research continues to prove impossible.
We can say that the interior of the Earth has many aspects that makes it a unique theme.

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viernes, 30 de septiembre de 2011

The Earth Crust.

The earth crust is comparatively thin layer, its thickness ranges from 3 km in the oceanic ridges and 70 km in large terrestrial mountain ranges like the Andes and the Himalayas.
The bottoms of the major ocean basins are formed by the oceanic crust, with an average thickness of 7 km is composed of mafic (iron-magnesium silicate) with an average density of 3.0 g / cubic cm.
The continents are composed of continental crust, which is composed of felsic rocks (silicates of sodium, potassium and aluminum), lighter, with an average density of 2.7 g / cubic cm.
The boundary between crust and mantle is manifested in two physical phenomena. First, there is a discontinuity in seismic velocity, which is known as the Mohorovicic discontinuity or "Moho." It is believed that this phenomenon is due to a change in the composition of rocks, some containing plagioclase feldspar (located at the top) to other feldspars have not (at the bottom). Second, there is a chemical discontinuity between ultramafic and harzburgite tectonizadas clusters, which has been observed in deeper parts of oceanic crust that have been obducidas within the continental crust and preserved as ophiolite sequences.