Glossary Database

Select a Letter to view the associated terms.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 Glossary Term: 

Definition:
 Vadose zone  Hydrologic zone of saturated subsurface conditions. Synonymous with saturated zone.
 Valley  Any hollow or low-lying land bounded by higher ground, such as hills or mountains, usually traversed by a stream or river.
 Valley glacier  A glacier that is confined to a stream valley. Synonymous with alpine glacier, mountain glacier.
 Vapor  The gaseous form of any substance that is normally a liquid or solid.
 Vaporization  To change to vapor.
 Varve  A pair of thin sedimentary layers, one relatively coarse-grained and light-colored, and the other relatively fine-grained and dark-colored, formed by deposition on a lake bottom during a period of one year. The coarse-grained layer is formed during spring runoff, and the fine-grained layer is formed during the winter when the surface of the lake is frozen.
 Vector  the carrier of an infectious agent, which acts to transfer an infection from one host to another (Morris 1992).
 Vein  A tabular rock body deposited in a fracture. Many ore minerals were deposited in veins when hot magma flowed through fractures.
 Velocity  Speed of motion along a direction (vector).
 Ventifact  A pebble or cobble shaped and polished by wind abrasion.
 vermiculations  Worm-like markings on the skin.
 Vertebrate  Any of a large division of animals having a spinal column (mammals, birds, etc). Having a backbone.
 Vesicle  A small hole formed in a volcanic rock by a gas bubble that became trapped as the lava solidified.
 Vestigial  Smaller and of more simple structure than in an evolutionary ancestor (Halliday 1987).
 Vibrissae  1. any of the erectile, tactile hairs found on the face of most mammals except humans. 2. any of the feathers near the mouth of many birds that may help in keeping insects caught as food from escaping (Morris 1992).
 Viscosity  The tendency of a body to resist flow. Increased viscosity implies a decrease in fluidity, or ability to flow.
 Viviparous  Bearing live young; having offspring that develop within the body and are born alive, rather than producing an egg that develops outside the body (Morris 1992).
 Voids (void space)  An empty space. In relation to geology the empty space between grains in the soil or a rock.
 Volatile  1. Capable of being readily vaporized. 2. A substance that can readily be vaporized, such as water or carbon dioxide.
 Volcanic ash  Dust-size particles ejected from a volcano.
 Volcanic bomb  A hard fragment of lava that was liquid or plastic at the time of ejection and acquired its form and surface markings during flight through the air. Volcanic bombs range from a few millimeters to more than a meter in diameter.
 Volcanic Debris   surface accumulation of loose material caused by a volcanic eruption
 Volcanic front  The line in a volcanic arc system (parallel to a trench) along which volcanism abruptly begins.
 Volcanic island arc  A curved chain of volcanic islands parallel to a deep-sea trench where oceanic lithosphere is subducted causing volcanism and the origin of volcanic islands.
 Volcanic neck  The solidified magma that originally filled the vent or neck of an ancient volcano and has subsequently been exposed by erosion.
 Volcanic vent  An opening through which lava and rock fragments erupt.
 Volcanism  The processes by which magma and gases are transferred from Earth's interior to the surface.
 Volcano  Conical, circular structure built by accumulation of lava flows and tephra.
 Volume  The amount of space occupied in three dimensions. A quantity, bulk, or amount.
 Vomer  1.) The narrow bone forming the lower and posterior half of the nasal septum (Morris 1992). 2.) A usually median unpaired bone on the roof of the mouth, often bearing teeth; also called prevomer.
 Vomerine teeth  Teeth lying on the vomer, in the palate of amphibians (Peters 1964).
 V-Shaped Valley   A young, narrow valley resulting from down cutting by a stream.