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Continental crust is a tertiary crust, formed at subduction zones through recycling of subducted secondary (oceanic) crust. [17] The average age of Earth's current continental crust has been estimated to be about 2.0 billion years. [20] Most crustal rocks formed before 2.5 billion years ago are located in cratons.
Tertiary crust is the most differentiated type of crust and so has a composition vastly different to that of the bulk Earth. [16] The tertiary crust contains over 20% of the abundance of incompatible elements , which are elements with a size or charge that prevent them from being included in mineral structure. [ 16 ]
The internal structure of Earth. In geology, the crust is the outermost solid shell of a planet, dwarf planet, or natural satellite.It is usually distinguished from the underlying mantle by its chemical makeup; however, in the case of icy satellites, it may be defined based on its phase (solid crust vs. liquid mantle).
The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation , while large sheets of ice at Earth's polar deserts retain more water than Earth's groundwater , lakes, rivers, and atmospheric ...
"This acceleration is directly related to the thinning of the crust." Below, you can see that the continents spend a lot of time moving along slowly, at rates shown in purples and blues.
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).
However, an alternative view proposes that Earth never experienced a vertical tectonic phase and that plate tectonics have been active throughout its entire history. [25] [26] [27] During this time, the Earth's crust cooled enough that rocks and continental plates began to form.
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