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Sima often takes the form of basalt when on the surface. In geology, sima (/ ˈsaɪmə /) 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 internal structure of Earth are the layers of the Earth, excluding its atmosphere and hydrosphere. The structure consists of an outer silicate solid crust, a highly viscous asthenosphere, and solid mantle, a liquid outer core whose flow generates the Earth's magnetic field, and a solid inner core. Scientific understanding of the internal ...
Sial. In geology, sial is an antiquated [1] blended term for the composition of the upper layer of Earth 's crust, namely rocks rich in aluminium silicate minerals. It is sometimes equated with the continental crust because it is absent in the wide oceanic basins, [2] but 'sial' is a geochemical term rather than a plate tectonic term. [3] As ...
Continental and oceanic crust on the upper mantle. Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its bulk composition is richer in aluminium ...
Conrad discontinuity. The Conrad discontinuity corresponds to the sub-horizontal boundary in the continental crust at which the seismic wave velocity increases in a discontinuous way. This boundary is observed in various continental regions at a depth of 15 to 20 km, but it is not found in oceanic regions. The Conrad discontinuity (named after ...
1. The meridian of longitude that is directly opposite or antipodal to a given meridian, i.e. the imaginary line that is exactly 180 degrees of longitude distant from the given meridian. Together, a meridian and its antimeridian form a great circle that passes through the geographic poles. 2.
The lines represent tectonic plate boundaries. Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. [1][2] The crust overlies the rigid uppermost ...
Geography of the Comoros. The Comoros archipelago consists of four main islands aligned along a northwest–southeast axis at the north end of the Mozambique Channel, between Mozambique and the island of Madagascar. Still widely known by their French names, the islands officially have been called by their Swahili names by the Comorian government.