Glossary Starting with the letter: B


A unit of pressure equal to the weight of the atmosphere at one hundred meters above mean sea level.


A dark-colored, fine-grained volcanic rock that contains more iron and magnesium and less silica than andesite (rhyolite, andesite and basalt span the compositional spectrum of common volcanic rocks).


The solid rock that underlies soil, sand, gravel, or other loose material.


A salt containing a cation (any positively-charged ion) and the radical HCO3, e.g., NaHCO3.


A mound-like or circumscribed mass of rock built almost exclusively of sedentary marine organisms that is embedded in a rock of different character.


The mass of living material.


All living organizsms on Earth, including in its atmostphere, its waters, and in the solid Earth.

Black Smoker

A chimney-like structure made primarily of sulfide minerals that forms around hydrothermal vents on the ocean floor.

Body Wave

A seismic wave that passes through the Earth, traveling outward from an earthquake focus (the point of first release of energy that causes an earthquake).

Bottom Water

The deepest (and usually coldest) layer of the oceans consisting of the water that is in contact with the ocean floor.


An isolated desert hillβ€”usually flat-topped and steep-sided, smaller than a mesa.