Earth Science: Exploring the Geology of Planet Earth

1807 Words Feb 7th, 2018 7 Pages
The physical geology of the earth consists of a Core (inner and outer), the mantle, the asthenosphere and the lithosphere. The inner core is primarily a solid ball about 70% the size of the moon and thought to consist of an iron-nickel alloy with a temperature about the same as the sun. The outer core is a liquid layer about 1500 mils thick that is composed of iron and nickel, just below the mantle. The mantle is divided into layers, and is a rocky shell surrounding the core of the earth with about 84% of the total volume of the planet. It is primarily solid and encloses the iron rich hot core and was formed by numerous past incidents of volcanism. Two main zones are in the upper mantle of the earth. The inner asthenosphere that is composed of flowing rock about 200 km thick and the lithosphere which is composed of rigid rock about 50-120 km thick. There is also a thick crust which is the upper part of the lithosphere that surrounds the mantle, anywhere from 5-75 km thick. Additionally, the asthenosphere may be described as being highly viscous that is crucial to the plate tectonic theory in that in spite of its high temperature, pressures keep it malleable and at a relatively low density. The lithosphere is the crust and upper mantle of the earth that is the hard and rigid layer in which humans live. This portion of the earth reacts to the atmosphere, hydrosphere and biosphere through erosion and weathering, resulting the soil forming…

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