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In geology, a continent is defined by continental crust, which is a platform of metamorphic and igneous rocks, largely of granitic composition. Continental crust is less dense and much thicker than oceanic crust, which causes it to "float" higher than oceanic crust on the dense underlying mantle. This explains why the continents form high ...
A biogeographic realm is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions.
Plate tectonics (from Latin tectonicus, from Ancient Greek τεκτονικός (tektonikós) ' pertaining to building ') [1] is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago.
Biogeography now incorporates many different fields including but not limited to physical geography, geology, botany and plant biology, zoology, general biology, and modelling. A biogeographer's main focus is on how the environment and humans affect the distribution of species as well as other manifestations of Life such as species or genetic ...
(Definitions of "continents" are a physical and cultural construct dating back centuries, long before the advent or even knowledge of plate tectonics; thus, defining a "continent" falls into the realm of physical and cultural geography (i.e. geopolitics), while continental plate definitions fall under plate tectonics in the realm of geology.)
The continental shelf and the slope are part of the continental margin. [6] The shelf area is commonly subdivided into the inner continental shelf, mid continental shelf, and outer continental shelf, [7] each with their specific geomorphology [8] [9] and marine biology. [10]
Continental-continental divergent/constructive boundary Oceanic divergent boundary: mid-ocean ridge (cross-section/cut-away view). In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other.
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).