5,021 articles
BOREAS (field campaign)
BOREAS, the Boreal Ecosystem-Atmosphere Study, was a large NASA-sponsored international field experiment in the boreal forests of central Canada, with main field campaigns in 1994 and 1996.
Borehole imaging
Borehole imaging is a well-logging technique in which downhole sensors produce oriented, high-resolution images of the borehole wall, using optical, acoustic, or electrical measurements to map fractures, bedding, and rock structures.
Bornite
Bornite is a copper iron sulfide mineral, Cu5FeS4, and an important ore of copper, best known for the iridescent blue and purple tarnish called "peacock ore."
Boset
Boset (Boset-Bericha, Boseti) is a twin stratovolcano complex (Gudda and Bericha) in the northern Main Ethiopian Rift, 17 x 20 km, summit 2,447 m, caldera formed after ~120 ka, with Holocene explosive eruptions including the ~600-year-old Boset Pumice.
Bottino
Bottino (Miniera del Bottino) is a historic lead-silver mine at Stazzema in the Apuane Alps, Tuscany, Italy. Worked from the Middle Ages, reopened by Cosimo I de' Medici in 1542, industrially developed in the 19th century, and definitively closed in 1969.
Bottom simulating reflector
A bottom simulating reflector (BSR) is a seismic reflection in marine sediment that mimics the seafloor and crosscuts layers, commonly indicating gas hydrate below continental margins.
Bottom-up control (ecology)
Bottom-up control is the regulation of a food web from its base, where resources like nutrients determine higher trophic levels, contrasting with top-down control by predators.
Bouguer anomaly
The Bouguer anomaly is a gravity anomaly corrected for elevation and the surrounding terrain, so remaining values reflect density variations used in mineral exploration and crustal studies.
Boulder field
Boulder field: a geomorphic term for boulder-covered landforms of glacial or periglacial origin, including block fields (felsenmeer), glacial till, and talus slopes; mostly Pleistocene relicts, 50,000–10,000 years old, that can persist through multiple glacial cycles.
Boundary mixing
Boundary mixing is turbulent mixing of a stratified fluid on sloping topography, such as ocean margins and lake beds, caused mainly by breaking internal waves.
Boundstone
Boundstone is a carbonate rock in the Dunham (1962) limestone classification whose original components were bound together organically during deposition, covering reefs, stromatolites, and travertine.
Boussinesq equations (water waves)
The Boussinesq equations for water waves describe weakly nonlinear, weakly dispersive waves in shallow water, first derived by Joseph Boussinesq in 1872 and now widely used in coastal modeling.
Bowen ratio
The Bowen ratio is the ratio of sensible heat flux to latent heat flux from a surface, named for Ira S. Bowen, who derived it in 1926.
Brackish water
Brackish water, also called brack water, is water whose salt content falls between that of freshwater and seawater, occurring naturally in estuaries and in some groundwater.
Bradgate Formation
Bradgate Formation: Ediacaran volcaniclastic unit of the Maplewell Group, Charnwood Forest, Leicestershire, at least 175 m thick, base dated 563 ± 1.9 Ma; hosts Charnia masoni and most Charnwood Ediacaran fossils.
Braer Storm
The Braer Storm was an extratropical cyclone over the North Atlantic, named for the tanker MV Braer, that reached a record low pressure of 914 mb on 10 January 1993.
Braided river
A braided river is a river that flows in multiple, mobile channels separated by temporary bars and islands, one of three classic channel patterns alongside meandering and straight.
Brazil Current
The Brazil Current is a warm, southward-flowing western boundary current of the South Atlantic Subtropical Gyre, forming where the South Equatorial Current splits near 15°S and meeting the Malvinas Current near 38°S.
Breccia
Breccia is a clastic rock composed of angular fragments larger than 2 mm held by mineral cement, its sharp-edged clasts distinguishing it from conglomerate, whose clasts are rounded by transport.
Brewer–Dobson circulation
The Brewer–Dobson circulation (BDC) is the stratosphere's global overturning circulation: air rises in the tropics, moves poleward, and descends in middle and high latitudes of each hemisphere, controlling ozone transport.
Bridge River Cones
The Bridge River Cones are a small basaltic volcanic field in the Garibaldi volcanic belt of southwest British Columbia, Canada, about 40 km west of Gold Bridge.
Bridgmanite
Bridgmanite is magnesium silicate perovskite, (Mg,Fe)SiO3, the most abundant mineral on Earth, dominating its lower mantle. It was named in 2014 for physicist Percy Bridgman.
Brier score
The Brier score measures the accuracy of probability forecasts for binary events by averaging the squared error between forecast probability and outcome. Glenn Brier introduced it in 1950.
Brine pool
A brine pool, also called an underwater lake, is a depression on the deep seafloor filled with dense hypersaline brine that pools like a lake, known from the Gulf of Mexico, Mediterranean, and Red Sea.
Brine rejection
Brine rejection is the process by which growing sea ice expels its salt into the surrounding ocean, leaving the ice fresher than the seawater it formed from.
Brinicle
A brinicle is a hollow, downward-growing tube of ice that forms beneath polar sea ice when dense, supercooled brine sinks and freezes surrounding seawater, sometimes reaching the seafloor.
British Geological Survey
The British Geological Survey is the United Kingdom's national geological survey, founded in 1835 and described as the world's oldest, providing geoscientific data, advice, and mapping to government, industry, and the public.
Brocken spectre
A Brocken spectre is the observer's own shadow, apparently enormously magnified, cast onto fog or cloud when the observer stands above the cloud layer with a low sun behind them.
Brownification
Brownification, also called browning, is the increase in the yellow-brown color of inland waters, driven mainly by rising dissolved organic matter of terrestrial origin across the Northern Hemisphere.
Brownmillerite
Brownmillerite is a reddish-brown calcium iron aluminate oxide mineral with the ideal formula Ca₂Fe³⁺AlO₅, occurring in thermally metamorphosed limestones in Israel and Germany and forming the ferrite phase of Portland cement clinker.