Banded iron ore: A sediment consisting of layers of chert alternating with bands of ferric iron oxides (hematite and limonite) in valuable concentrations.

Barchan: A crescent-shaped sand dune moving across a clean surface with its convex face upwind and its concave slip face downwind.

BARREL:A volumetric unit of measure for crude oil and petroleum products.

Basalt: A fine-grained, dark, mafic igneous rock composed largely of plagioclase feldspar and pyroxene.

Base-level: The level below which a stream cannot erode; usually sea level sometimes locally the level of a lake or resistant formation.

Basement: The oldest rocks recognized in a given area, a complex of metamorphic and igneous rocks that underlies all the sedimentary formations. Usually Precambrian or Paleozoic in age.


Basic rock: Any igneous rock containing mafic minerals rich in iron and magnesium, but containing no quartz and little sodium rich plagioclase feldspar.




Basin: In tectonics, a circular, syncline-like depression of strata. In sedimentology, the site of accumulation of a large thickness of sediments.



Batholith: A great irregular mass of coarse-grained igneous rock with an exposed surface of more than 100 square kilometers, which has either intruded the country rock or been derived from it through metamorphism.

Bauxite: A rock composed primarily of hydrous aluminum oxides and formed by weathering in tropical areas with good drainage; a major ore of aluminum.

Bedding: A characteristic of sedimentary rocks in which parallel planar surfaces separating different grain sizes or compositions indicate successive depositional surfaces that existed at the time of sedimentation.

Bed-load: The sediment that a stream moves along the bottom of its channel by rolling and bouncing.

Beta-particle: An electron emitted with high energy and velocity from a nucleus undergoing radioactive decay.

B-horizon: The intermediate layer in a soil, situated below the A-horizon and consisting of clays and oxides. Also called the zone of accumulation.

Biochemical precipitate: A sediment, especially of limestone or iron, formed from elements extracted from seawater by living organisms.

Bituminous coal: A soft coal formed by an intermediate degree of metamorphism and containing 15 to 20 percent volatiles. The most common grade of coal.

Block fault: A structure formed when the crust is divided into blocks of different elevation by a set of normal faults.

Blowout: A shallow circular or elliptical depression in sand or dry soil formed by wind erosion.

Bore: To enlarge and finish the surface of a cylindrical hole by the action of a rotating boring bar (cutting tool) or by the action of a stationary tool pressed (fed) against the surface as the part is rotated.

Butte: A steep sided and flat topped hill formed by erosion of flat laying strata where remnants of a resistant layer protect the softer rocks underneath.

BYTE:Eight related bits of data or an eight-bit binary number. Also denotes the amount of memory required to store one byte of data