Oceanic crust is about 6 km 4 miles thick. It is composed of several layers, not including the overlying sediment. The topmost layer, about metres 1, feet thick, includes lavas made of basalt that is, rock material consisting largely of plagioclase [ feldspar ] and pyroxene. Oceanic crust differs from continental crust in several ways: it is thinner, denser, younger, and of different chemical composition. Like continental crust, however, oceanic crust is destroyed in subduction zones. The lavas are generally of two types: pillow lavas and sheet flows.
Seafloor spreading is a geologic process where there is a gradual addition of new oceanic crust in the ocean floor through a volcanic activity while moving the older rocks away from the mid-oceanic ridge. Seafloor spreading was proposed by an American geophysicist, Harry H. Hess in By the use of the sonar, Hess was able to map the ocean floor and discovered the mid-Atlantic ridge mid-ocean ridge. He also found out that the temperature near to the mid-Atlantic ridge was warmer than the surface away from it.
Paleomagnetism , or palaeomagnetism , is the study of the record of the Earth's magnetic field in rocks, sediment, or archeological materials. Magnetic minerals in rocks can lock-in a record of the direction and intensity of the magnetic field when they form. This record provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates. The record of geomagnetic reversals preserved in volcanic and sedimentary rock sequences magnetostratigraphy provides a time-scale that is used as a geochronologic tool.
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All сomments (12)
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He is a very happy man
Bang'n azz Tits.damn
Oh, wooowww . Wie lecker die Pussy ausieht.
mmmm yes very sexy *. lets team up baby and make him cum, over and over again
hhmm lovely
Wow mama! Your true hottie! Keep taking photos, we all love 'em!
so sexy.
damn i wanna destroy that pussyso hot
delischious:
mmmm. let me see them! nice body
Alright. I think I found THE perfect ass! Incredible!
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