Search results
Results from the WOW.Com Content Network
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).
The estimated average density of the continental crust is 2.835 g/cm 3, with density increasing with depth from an average of 2.66 g/cm 3 in the uppermost crust to 3.1 g/cm 3 at the base of the crust. [14] In contrast to the continental crust, the oceanic crust is composed predominantly of pillow lava and sheeted dikes with the composition of ...
The result is that the crust in the collision zone becomes as much as 80 kilometers (50 mi) thick, [20] versus 40 kilometers (25 mi) for average continental crust. [21] As noted above , the Airy hypothesis predicts that the resulting mountain roots will be about five times deeper than the height of the mountains, or 32 km versus 8 km.
Upper mantle. The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (at about 10 km (6.2 mi) under the oceans and about 35 km (22 mi) under the continents) and ends at the top of the lower mantle at 670 km (420 mi). Temperatures range from approximately 500 K (227 °C; 440 °F) at the ...
In contrast, continental crust is thick (~45 km thick) and buoyant, composed mostly of granitic rocks (average density about 2.5 g/cm 3). Continental crust is subducted with difficulty, but it is subducted to depths of 90–150 km or more, as evidenced by ultra-high pressure (UHP) metamorphic suites. Normal subduction continues as long as the ...
Earth's crustal evolution involves the formation, destruction and renewal of the rocky outer shell at that planet 's surface. The variation in composition within the Earth's crust is much greater than that of other terrestrial planets. Mars, Venus, Mercury and other planetary bodies have relatively quasi-uniform crusts unlike that of the Earth ...
The thin parts are the oceanic crust, which underlies the ocean basins (5–10 km) and is mafic-rich [9] (dense iron-magnesium silicate mineral or igneous rock). [10] The thicker crust is the continental crust, which is less dense [11] and is felsic-rich (igneous rocks rich in elements that form feldspar and quartz). [12]
Sinistral transform. Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) 'pertaining to building') is the scientific theory that Earth 's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of continental ...