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An instrument that measures the magnitude and/or direction of a magnetic field. A magnetometer can be either a scalar instrument that measures the magnitude of the total field or a vector instrument that measures one or more vector components of the…

A term applied commercially to any limestone or dolomite taking polish. Marble is extensively used for building and ornamental purposes.Limestone Stone and stone productsIn petrography the term marble is applied to metamorphic rocks composed of…

The collection and observation of living organisms in the sea, including the quantitative determination of their abundance in time and space. The biological survey of the ocean largely depends on specially equipped vessels. Sampling in intertidal…

The management of marine species and ecosystems to prevent their decline and extinction. As in terrestrial conservation, the goal of marine conservation is to protect biodiversity and ecosystem function through the preservation of species,…

An integrative science that studies the basic structural and functional relationships within and among living populations and their physical–chemical environments in marine ecosystems. Although an outgrowth of natural history and the life sciences,…

The harvest of animals and plants from the ocean to provide food for people and animals. Marine fisheries are places or industries engaged in the harvesting of aquatic life in seawaters. Important products in marine capture fisheries include fish…

A scientific discipline applying the principles and methods of general microbiology to research in marine biology and biogeochemistry. Marine microbiology investigates microorganisms living in saltwater environments. Dealing, by definition, with…

The branch of geography that examines human and physical activities on the Earth's surface using models and statistical analysis. The primary areas in which mathematical methods are used include the analysis of spatial patterns, the processes that…

A naturally occurring solid phase with a restricted chemical composition and a definite atomic arrangement. This is really an idealized definition insofar as some minerals (especially those that form at low temperature) have poorly defined atomic…

A distorted scene of distant objects resulting from the passage of light through a nonuniform medium. In a uniform atmosphere light would travel in straight lines and distant scenes would appear without distortion. Since the density of the air…

The smallest of the four major deserts in the North American Desert region in the continental United States and is located in the southwestern quadrant of the Basin and Range physiographic province in southeastern California and portions of Arizona,…

A group name for all clay minerals with an expanding structure, except vermiculite, and also a specific mineral name for the high alumina end member of the group. VermiculiteMontmorillonite clays have wide commercial use. The high colloidal,…

The formation of nuclides present in the universe by various nuclear reactions. Theories of the origin of the elements involve synthesis with charged and neutral elementary particles (neutrons, protons, neutrinos, photons) and other nuclear building…

An isolated fertile area, usually limited in extent and surrounded by desert. The term was initially applied to small areas in Africa and Asia typically supporting trees and cultivated crops with a water supply from springs and from seepage of water…

The general circulation of the ocean. The term is usually understood to include large-scale, nearly steady features, such as the Gulf Stream (Fig. 1), as well as current systems that change seasonally but are persistent from one year to the next,…

Propagating oscillations in the ocean that carry energy and momentum from one region to another. Most ocean waves (Fig. 1) are caused directly or indirectly by wind blowing across the sea surface. Many waves can propagate through the ocean thousands…

The science of the sea, including physical oceanography, marine chemistry, marine geology, and marine biology. The need to know more about the impact of marine pollution and possible effects of the exploitation of marine resources, together with the…

Waters of varying mineral content which are found associated with petroleum and natural gas or have been encountered in the search for oil and gas. They are also called oil-field brines, or brines. They include a variety of underground waters,…

A name given to a group of magnesium-iron silicate minerals crystallizing in the orthorhombic system. Crystals are usually of simple habit, a combination of the dipyramid with prisms and pinacoids. The luster is vitreous and the color olive green,…

The study of the abundance and composition of naturally occurring organic substances, their origins and fate, and the processes that affect their distributions on Earth and in extraterrestrial materials.Organic geochemistry was born from a curiosity…

A mineral having composition As2S3 and crystallizing in the monoclinic system. Crystals are small, tabular, and rarely distinct (see illustration); the mineral occurs more commonly in foliated or columnar masses. There is one perfect cleavage…

A geographic designation that includes thousands of mainly small coral and volcanic islands scattered across the Pacific Ocean from Palau in the west to Easter Island in the east. Island archipelagos off the coast of the Asian mainland, such as…

The largest of the world's oceans, having an area of 1.65 × 108 km2 (6.3 × 107 mi2) and a mean depth of 4282 m (14,049 ft).The Pacific Ocean covers 32% of the Earth's surface and 46% of the surface of all oceans and seas and its area is greater than…

A soil of the past, that is, a fossil soil. Paleosols are most easily recognized when they are buried by sediments. They also include surface profiles that are thought to have formed under very different conditions from those now prevailing, such as…

Any of the oriented intergrowths of potassium- and sodium-rich feldspars, (K,Na)AlSi3O8, whose proportions are determined in part by the initial composition of the alkali feldspar from which they exsolved and whose physical properties are thus…