Earth Sciences, TRO-WUR
The Earth sciences are the fields of study concerned with the solid Earth, its waters, and the air that envelops it. Included are the geologic, hydrologic, and atmospheric sciences.
Earth Sciences Encyclopedia Articles By Title
tropical wet-dry climate, major climate type of the Köppen classification characterized by distinct wet and dry......
troposphere, lowest region of the atmosphere, bounded by the Earth beneath and the stratosphere above, with its......
tsunami, catastrophic ocean wave, usually caused by a submarine earthquake, an underwater or coastal landslide,......
tuff, a relatively soft, porous rock that is usually formed by the compaction and cementation of volcanic ash or......
tundra climate, major climate type of the Köppen classification characterized by sub-freezing mean annual temperatures,......
turbidite, a type of sedimentary rock composed of layered particles that grade upward from coarser to finer sizes......
turbidity current, underwater density current of abrasive sediments. Such currents appear to be relatively short-lived,......
Turonian Stage, second of six main divisions (in ascending order) in the Upper Cretaceous Series, representing......
turquoise, hydrated copper and aluminum phosphate [CuAl6(PO4)4(OH)8·4H2O] that is extensively used as a gemstone.......
twilight glow, weak, widespread, and relatively steady glow from the sky that is observed around twilight; it is......
Typhon, in Greek mythology, youngest son of Gaea (Earth) and Tartarus (of the nether world). He was described as......
tyuyamunite, radioactive, yellow, soft, and waxy uranium and vanadium oxide mineral, Ca(UO2)2(VO4)2·5–8H2O. It......
ulexite, borate mineral, NaCaB5O6(ΟH)6·5H2O, that consists of hydrated sodium and calcium borate. Individual crystals......
Ultisol, one of the 12 soil orders in the U.S. Soil Taxonomy. Ultisols are reddish, clay-rich, acidic soils that......
umangite, a copper selenide (Cu3Se2) occurring only in small grains or fine granular aggregates with other copper......
Umbrisol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
undertow, a strong seaward bottom current returning the water of broken waves back out to sea. There is in fact......
uniformitarianism, in geology, the doctrine suggesting that Earth’s geologic processes acted in the same manner......
Mount Unzen, volcano on central Shimabara Peninsula, western Kyushu, Japan. Mount Unzen is actually a group of......
updraft and downdraft, in meteorology, upward-moving and downward-moving air currents, respectively, that are due......
uplift, in geology, an increase in the vertical elevation of Earth’s surface in response to natural causes. Broad,......
Uralian emerald, yellowish green or emerald-green andradite, a variety of garnet, not emerald. See...
uraninite, a major ore mineral of uranium, uranium dioxide (UO2). Uraninite usually forms black, gray, or brown......
uranium-234–uranium-238 dating, method of age determination that makes use of the radioactive decay of uranium-238......
uranium-thorium-lead dating, method of establishing the time of origin of a rock by means of the amount of common......
urban climate, any set of climatic conditions that prevails in a large metropolitan area and that differs from......
uvarovite, calcium chromium garnet found as small, brilliant, green crystals. It is the rarest of all the garnets,......
vadose zone, region of aeration above the water table. This zone also includes the capillary fringe above the water......
Valanginian Stage, second of six main divisions (in ascending order) in the Lower Cretaceous Series, representing......
Van Allen radiation belt, doughnut-shaped zones of highly energetic charged particles trapped at high altitudes......
Van earthquake of 2011, severe earthquake that struck near the cities of Erciş and Van in eastern Turkey on October......
vanadate mineral, any of the many naturally occurring compounds of vanadium (V), oxygen (O), and various metals;......
vanadinite, vanadium mineral in the pyromorphite series of the apatite group of phosphates, lead chloride vanadate,......
variscite, phosphate mineral, hydrated aluminum phosphate (AlPO4·2H2O), which is valued as a semiprecious gemstone......
varved deposit, any form of repetitive sedimentary rock stratification, either bed or lamination, that was deposited......
vein, in geology, ore body that is disseminated within definite boundaries in unwanted rock or minerals (gangue).......
ventifact, stone that has received one or more highly polished, flattened facets as a result of erosion by windblown......
Venus’s-hairstone, variety of quartz interspersed with fine crystals of the mineral rutile...
vermiculite, clay mineral similar to montmorillonite in structure and, in some cases, composition. Vermiculite......
Vertisol, one of the 12 soil orders in the U.S. Soil Taxonomy. Vertisols are clay-rich soils that undergo significant......
Vertisol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
vesuvianite, common silicate mineral that occurs in crystalline limestones near their contacts with igneous rocks,......
Vesuvius, active volcano that rises above the Bay of Naples on the plain of Campania in southern Italy. Its western......
Virgilian series, major division of Late Carboniferous rocks and time in the United States (the Late Carboniferous......
Viséan Stage, second of three internationally defined stages of the Mississippian Subsystem of the Carboniferous......
vivianite, phosphate mineral, hydrated iron phosphate [Fe3(PO4)2·8H2O], that occurs as colourless when freshly......
volcanic eruption, an eruption of molten rock, hot rock fragments, and hot gases through a volcano, which is a......
volcanic glass, any glassy rock formed from lava or magma that has a chemical composition close to that of granite......
volcanic winter, cooling at Earth’s surface resulting from the deposition of massive amounts of volcanic ash and......
volcanism, any of various processes and phenomena associated with the surficial discharge of molten rock, pyroclastic......
volcano, vent in the crust of Earth or another planet or satellite, from which issue eruptions of molten rock,......
- Introduction
- Lava, Gas, Hazards
- Ash Falls, Eruptions, Magma
- Secondary Damage, Eruptions, Hazards
- Eruptions, Types, Magma
- Pinatubo, Philippines, 1991
- Hawaii, Mauna Loa, 1984
- Vesuvius, Tambora, Krakatoa, Pelee
- Forecasting, Warning, Monitoring
- Eruptions, Cone, Magma
- Calderas, Magma, Eruptions
- Lava Domes, Magma, Eruptions
- Eruptions, Magma, Structure
- Hot Springs, Geysers, Magma
- Plate Boundaries, Magma, Eruptions
- Rift, Magma, Eruptions
- Magma, Eruptions, Geothermal
volcanology, discipline of the geologic sciences that is concerned with all aspects of volcanic phenomena. Volcanology......
Waal Interglacial Stage, division of Pleistocene time and deposits in the Netherlands and northern Europe (the......
wacke, sedimentary rock composed of sand-sized grains (0.063–2 mm [0.0025–0.078 inch]) with a fine-grained clay......
wad, black and earthy substance that consists mainly of hydrated manganese oxides; it is an important ore of manganese.......
wairakite, hydrated calcium aluminosilicate mineral present in hot-spring deposits, notably those at Wairakei,......
water cycle, cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many......
water mass, body of ocean water with a distinctive narrow range of temperature and salinity and a particular density......
water table, upper level of an underground surface in which the soil or rocks are permanently saturated with water.......
Waterberg Series, major division of rocks in southern Africa. The age of the Waterberg is in doubt; it is possible......
waterspout, a small-diameter column of rapidly swirling air in contact with a water surface. Waterspouts are almost......
Waucoban Series, lowermost Cambrian rocks (the Cambrian Period lasted from 542 million to 488 million years ago);......
wave, a ridge or swell on the surface of a body of water, normally having a forward motion distinct from the oscillatory......
wavellite, hydrated aluminum phosphate [Al3(PO4)2(OH)3·5H2O], a common phosphate mineral that typically occurs......
weather, state of the atmosphere at a particular place during a short period of time. It involves such atmospheric......
weather bureau, agency established by many countries to observe and report the weather and to issue weather forecasts......
weather forecasting, the prediction of the weather through application of the principles of physics, supplemented......
weather map, any map or chart that shows the meteorological elements at a given time over an extended area. The......
weather modification, the deliberate or the inadvertent alternation of atmospheric conditions by human activity,......
weather satellite, any of a class of Earth satellites designed to monitor meteorological conditions (see Earth...
weathering, disintegration or alteration of rock in its natural or original position at or near the Earth’s surface......
Weichsel Glacial Stage, major division of late Pleistocene deposits and time in western Europe (the Pleistocene......
welded tuff, rock composed of compacted volcanic ejecta (see...
Wenlock Series, the second of four main divisions (in ascending order) of the Silurian System, representing those......
West African monsoon, a major wind system that affects West African regions between latitudes 9° and 20° N and......
West Greenland Current, cool flow of water proceeding northward along the west coast of Greenland. See Greenland...
wet equatorial climate, major climate type of the Köppen classification characterized by consistently high temperatures......
Whakaari/White Island, island in the Bay of Plenty, 43 miles (69 km) west of Cape Runaway, eastern North Island,......
whirlpool, rotary oceanic current, a large-scale eddy that is produced by the interaction of rising and falling......
whirlwind, a small-diameter columnar vortex of rapidly swirling air. A broad spectrum of vortices occurs in the......
White Island volcanic eruption of 2019, volcanic eruption on December 9, 2019, on Whakaari/White Island, located......
white mica, fine-grained variety of any of the silicate minerals muscovite, paragonite, or talc...
Wichita orogeny, a period of block faulting in the southern part of the Wichita–Arbuckle System in western Oklahoma......
willemite, white or greenish yellow silicate mineral, zinc silicate, Zn2SiO4, that is found as crystals, grains,......
wind, in climatology, the movement of air relative to the surface of the Earth. Winds play a significant role in......
wind chill, a measure of the rate of heat loss from skin that is exposed to the air. It is based on the fact that,......
wind rose, map diagram that summarizes information about the wind at a particular location over a specified time......
wind shear, rapid change in wind velocity or direction. A very narrow zone of abrupt velocity change is known as......
windstorm, a wind that is strong enough to cause at least light damage to trees and buildings and may or may not......
winter, coldest season of the year, between autumn and spring; the name comes from an old Germanic word that means......
Wisconsin Glacial Stage, most recent major division of Pleistocene time and deposits in North America, which began......
witherite, a carbonate mineral, barium carbonate (BaCO3), that is, with the exception of barite, the most common......
Witteberg series, uppermost member of the Cape System of sedimentary rocks in South Africa. It consists of about......
wolframite, chief ore of tungsten, commonly associated with tin ore in and around granite. Such occurrences include......
wollastonite, white, glassy silicate mineral that commonly occurs as masses or tabular crystals with other calcium-containing......
Wordian Stage, second of three stages of the Middle Permian (Guadalupian) Series, made up of all rocks deposited......
World Meteorological Organization (WMO), specialized agency of the United Nations (UN) created to promote the establishment......
Wuchiapingian Stage, first of two stages of the Upper Permian (Lopingian) Series, encompassing all rocks deposited......
wulfenite, lead molybdate, PbMoO4, a minor source of molybdenum and the second most common molybdenum mineral.......
wurtzite, a zinc sulfide mineral that occurs typically in Potosí, Bolivia; Butte, Mont.; and Goldfield, Nev. It......