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Sima often takes the form of basalt when on the surface. In geology, sima (/ ˈ s aɪ m ə /) is an antiquated [1] blended term for the lower layer of Earth's crust. This layer is made of rocks rich in magnesium silicate minerals. Typically, when the sima comes to the surface, it is basalt, so sometimes this layer is called the 'ocean layer' of ...
The thickness of Earth's crust (km). The continental crust consists of various layers, with a bulk composition that is intermediate (SiO 2 wt% = 60.6). [5] The average density of the continental crust is about, 2.83 g/cm 3 (0.102 lb/cu in), [6] less dense than the ultramafic material that makes up the mantle, which has a density of around 3.3 g/cm 3 (0.12 lb/cu in).
Under laboratory conditions a sample of iron–nickel alloy was subjected to the core-like pressure by gripping it in a vise between 2 diamond tips (diamond anvil cell), and then heating to approximately 4000 K. The sample was observed with x-rays, and strongly supported the theory that Earth's inner core was made of giant crystals running ...
Because of the large pressures, over geologic time, the sima flows like a very viscous liquid, so, in a real sense, the sial floats on the sima, in isostatic equilibrium. [9] Mountains extend down as well as up, much like icebergs on the ocean; [ 9 ] so that on the continental plates , the sial runs between 5 km and 70 km deep.
Therefore, the seismologists of that time considered that the Conrad discontinuity should correspond to a sharply defined contact between the chemically distinct two layers, sial and sima. [2] Despite the fact that sial and sima are two solid layers, the lighter sial is thought to "float" on top of the denser sima layer.
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Basalt. A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron.Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite.
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