Encyclopedia of Earth Science

Hydrothermal vent systems that form near active magmatic systems along the mid-ocean ridge system, approximately 2 miles (3 km) below sea level. Th…

A common black, dark brown, or green mineral of the mica group. It is an aluminosilicate with the formula K(Mg,Fe+2)3(Al,Fe+3)Si3O10(OH)2 and is a …

The biosphere encompasses the part of the Earth that is inhabited by life, and includes parts of the lithosphere, hydrosphere, and atmosphere. Life…

Sediments that are produced directly by the physiological activities of plants or animals. Rocks derived from biogenic sediments include both subaq…

One of several possible theoretical beginning moments of the universe. One of the deepest questions in cosmology, the science that deals with the s…

The benthic environment includes the ocean floor, and the benthos are those organisms that dwell on or near the seafloor. Bottom-dwelling benthos o…

Well-defined, uniformly fixed point on the land’s surface that is used for a reference point from which other measurements can be made. It is gener…

The Archean Belingwe greenstone belt in southern Zimbabwe has proved to be one of the most important Archean terranes for testing models for the e…

Also known as stratification, bedding is a primary depositional layering in sedimentary rocks that is defined by variations in grain size of clasti…

An accumulation of sediment exposed to wave action along a coastline. The beach extends from the limit of the low-tide line to the point inland whe…

Aluminous ore produced by intense humid tropical weathering of limestone, basalt, shale, marl, or virtually any igneous, metamorphic, or sedimentar…

Large igneous intrusion with a surface area greater than 60 square miles (100 km2). Several types of igneous intrusions are produced by magmas (gen…

The Basin and Range Province of the United States extends from eastern California to central Utah, and from southern Idaho into the state of Sonor…

A depression in the surface of the Earth or other celestial body. There are many types of basins, including depressed areas with no outlet or with …

Dark-colored rocks with low silica contents generally falling between 44 and 52 percent. They include one of four groups of rocks classified based …

Narrow elongate deposits of sand situated offshore and generally elongate parallel to the main shoreline. They are typically only elevated slightly…

A distinctive type of sedimentary rock that formed predominantly during the Precambrian and is the major source of the world’s iron reserves. Bande…

The Baltic (Fennoscandian) shield is an Archean craton that traditionally is divided into three distinct parts. The northern, Lapland-Kola province…

An elongate peninsula extending about 760 miles (1,225 km) south from southern California. It is separated from mainland Mexico by the Gulf of Cali…

An erosional landform that develops in arid to semiarid terranes, characterized by a very high drainage density (77 to 747 miles per square mile), …

Aurora Borealis and Aurora Australis are glows that are sometimes visible in the Northern and Southern Hemispheres, respectively. They are informal…

Consisting of circular, elliptical, or semicircular islands made of coral reefs that rise from deep water, atolls surround central lagoons, typical…

A series of mountains and plateaus in northwest Africa extending about 1,500 miles (2,500 km) in southwest Morocco, northern Algeria, and northern …

An elevated arid region located in northern Chile, extending over 384 square miles (1,000 km2) south from the border with Peru. The desert is locat…

The layer of the mantle between the lithosphere and mesosphere. Its depth in the Earth ranges from about 155 miles (250 km) to 0 miles below the mi…

A commercial term for a group of silicate minerals that form thin, strong, heat resistant fibers. These minerals include several varieties from the…

A well that taps confined groundwater. In many regions, a permeable layer, typically sandstone, is confined between two impermeable beds, creating …

A large inland sea in southwestern Kazakhstan and northwest Uzbekistan, east of the Caspian Sea. The Aral Sea is fed by the Syr Darya and Amu Darya…

The Arabian shield comprises the core of the Arabian Peninsula, a landmass of near trapezoidal shape bounded by three water bodies. The Red Sea bou…