An estimate of the true age of a mineral or rock based on the rate of decay of radioactive minerals.
A volcano that is erupting; or one that, while not erupting at the present, has erupted within (geologically) recent time and is considered likely to do so in the (geologically) near future.
The rate of temperature change in the atmosphere due to the raising or lowering of an air mass. the "dry adiabatic rate" is 5.5 deg. f. per 1000 feet, while the "wet" rate is 3...
- A general term for clay, silt, sand, gravel or similar unconsolidated material deposited by a stream or other body of running water.
- Gravel, sand, silt, soil, or other material that...
Intermediate volcanic rocks containing 54 to 62 percent silica and moderate amounts of iron and magnesium. andesite minerals commonly include plagioclase and hornblende, with lesser amounts of mic... андезит;
An impermeable geologic formation or stratum which will not hold or transmit fluid. водоупор;
A geologic formation or stratum that significantly retards fluid movement. проницаемый водоупор;
The unnatural addition of surface waters to groundwater. recharge could result from reservoirs, storage basins, leaky canals, direct injection of water into an aquifer, or by spreading water over ...
A turbulent mixture of gas and rock fragments, most of which are ash-sized particles, ejected violently from a crater or fissure. the mass of pyroclastics is normally of very high temperature and ...
Volcanic ash that has fallen through the air. the resulting deposit is usually well sorted and exhibits a finely layered structure.
- Volcanic rock (or magma) that is generally dark in color, contains 45 to 54 percent silica, and is rich in iron and magnesium. an eruption of basaltic magma is generally quiet, and results in ...
The study and classification of rocks and their history based on their fossil content.
- Angular fragments of material, commonly formed by physical weathering processes or explosive volcanic activity.
- Any stone composed of angular fragments embedded and consolidated in ...
|brittle-ductile transition zone|
The location at depth within the earth`s crust where the temperature and pressure have risen to such a high level that directed stress results in plastic deformation as opposed to fracturing and f...
The spanish word for cauldron, a basin-shaped volcanic depression; by definition, at least a mile in diameter. such large depressions are typically formed by the subsidence of volcanoes. crater la... кальдера;
Erosional features associated with alpine glaciers.
A volcanic cone built entirely of loose fragmented material (pyroclastics.)
A steep volcanic cone built by both lava flows and pyroclastic eruptions.
Water included in the groundwater which is derrived from the rock itself, as opposed to water which has percolated down from the surface.
Solid, outer layers of the earth, including the rocks of the continents.
The theory that horizontal movement of the earth`s surface causes slow, relative movements of the continents toward or away from one another.
Volcanic rock (or lava) that characteristically is light in color and contains 62 to 69 percent silica and moderate amounts of sodium and potassium. дацит;
A flow of unsorted masses of rock and other material downslope under the influence of gravity. water is commonly involved as a catalyst and/or lubricant. for example
The surface along which a landslide disconnects from its original position.
The arrangement of the hydrogen atoms of a water molecule at 105 deg. across the oxygen results in a slight electrical charge to the molecule. it also results in water molecules looking like micke...
This term is used to describe a volcano which is presently inactive but which may erupt again. the major volcanic cones of the cascade mountains (in washington, oregon, and california) are believe...
General term for material deposited by a glacier.
Material that is thrown out by a volcano, including pyroclastic material (tephra) and, from some volcanoes, lava bombs.
Large rocks or other debris deposited by a glacier, usually in an area far removed from its source. commonly used to indicate a big chunk of debris which is clearly out of place and shouldn`t even...
The column of gases, ash, and larger rock fragments rising from a crater or other vent. if it is of sufficient volume and velocity, this gaseous column may reach many miles into the stratosphere, ...
The opening through which volcanic material is emitted.
Water used by plants and animals and subsequently returned directly to the atmosphere. fly-off; эвапотранспирация;
A volcano that is not presently erupting and is not likely to do so for a very long time in the future.
An eruption from the side of a volcano (in contrast to a summit eruption.)
The low relief lands bordering a stream or river, common to the mature and old age stages of stream development. floodplains store excess water in times of high water, and excess sediments in time... пойма;
Evidence of past life on earth. can include the preserved hard and soft parts of plants and animals, tracks and burrows, whole organisms preserved intact in amber or tar, and fossilized dung. any ... ископаемое; ископаемое, окаменелость;
A vent or opening through which issue steam, hydrogen sulfide, or other gases. the craters of many dormant volcanoes contain active fumaroles. фумарола;
Your`s truly, and a real geogeek.
Energy derived from the internal heat of the earth.
Power generated by using the heat energy of the earth.
A copmmon mechanical weathering process where rock and debris frozen into the sides and bottom of a glacier act like sandpaper and wear down the bedrock the glacier is mocing across.
Naturally occurring ice which exhibits internal plastic flow and deformation.
Polished bedrock surfaces left behind after melting of glacial ice. the polishing is probably due to very fine grained rock flour carried at the base of the ice.
|glacial quarrying (plucking)|
A common mechanical weathering process in alpine glaciated terrain where glacial ice frozen into cracks in the bedrock literally "pluck" rock material from the valley floor.
An elongate crustal block that is relatively depressed (downdropped) between two fault systems. грабен;