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Crust (geology) 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 distinguished based on its phase (solid crust vs. liquid mantle).
Earth's crust is its thick outer shell of rock, referring to less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth 's layers that includes the crust and the upper part of the mantle. [1] The lithosphere is broken into tectonic plates whose motion allows heat to escape ...
Earth's inner core is the innermost geologic layer of the planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 19% of Earth's radius [0.7% of volume] or 70% of the Moon 's radius. [32][33] The inner core was discovered in 1936 by Inge Lehmann and is generally composed primarily of iron and some nickel.
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left ...
Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium ) and continental crust ( sial from silicon and aluminium ).
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 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).
Solidified lava flow in Hawaii Sedimentary layers in Badlands National Park, South Dakota Metamorphic rock, Nunavut, Canada. Geology (from Ancient Greek γῆ (gê) 'earth' and λoγία () 'study of, discourse') [1] [2] is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. [3]