Earth Sciences, TAC-UMA
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
taconite
taconite, a low-grade siliceous iron ore composed of 20–30 percent magnetite that occurs in fine-grained banded......
Taenite
Taenite, nickel-iron mineral having a face-centred cubic structure and playing a major role in the crystallization......
Taiwan earthquake of 1999
Taiwan earthquake of 1999, earthquake that began at 1:47 am local time on Sept. 21, 1999, below an epicentre 93......
talc
talc, common silicate mineral that is distinguished from almost all other minerals by its extreme softness (it......
Tambora, Mount
Mount Tambora, volcanic mountain on the northern coast of Sumbawa island, Indonesia, that in April 1815 exploded......
Tangshan earthquake of 1976
Tangshan earthquake of 1976, earthquake on July 28, 1976, with a magnitude of 7.5, which nearly razed the Chinese......
tantalum
tantalum (Ta), chemical element, bright, very hard, silver-gray metal of Group 5 (Vb) of the periodic table, characterized......
tar sand
tar sand, deposit of loose sand or partially consolidated sandstone that is saturated with highly viscous bitumen.......
Tarantian Stage
Tarantian Stage, last of four stages of the Pleistocene Series, encompassing all rocks deposited during the Tarantian......
Tarhun
Tarhun, ancient Anatolian weather god. His name appears in Hittite and Assyrian records (c. 1400–612 bc) and later......
Tasman Geosyncline
Tasman Geosyncline, a linear trough in the Earth’s crust in which rocks that formed during the Paleozoic Era (542......
tectogene
tectogene, great downbuckle of the Earth’s crust into the mantle below deep-sea trenches that are filled with marine......
tectonics
tectonics, scientific study of the deformation of the rocks that make up the Earth’s crust and the forces that......
tectosilicate
tectosilicate, any member of a group of compounds with structures that have silicate tetrahedrons (each of which......
Teide Peak
Teide Peak, volcanic peak at the centre of the island of Tenerife, in the Santa Cruz de Tenerife provincia (province)......
tektite
tektite, any of a class of small, natural glassy objects that are found only in certain areas of Earth’s surface.......
tellurium
tellurium (Te), semimetallic chemical element in the oxygen group (Group 16 [VIa] of the periodic table), closely......
Telychian Stage
Telychian Stage, last of three stages of the Llandovery Series, encompassing all rocks deposited during the Telychian......
Temperature inversion
Temperature inversion, a reversal of the normal behaviour of temperature in the troposphere (the region of the......
Temperature–humidity index
Temperature–humidity index (THI), combination of temperature and humidity that is a measure of the degree of discomfort......
tenorite
tenorite, copper oxide mineral (CuO) found as gray-to-black metallic crystals as a sublimation product on lavas.......
tephrochronology
tephrochronology, method of age determination that makes use of layers of ash (tephra). Tephra layers are excellent......
tephroite
tephroite, olivine mineral found only in iron-manganese ore deposits and skarns and in metamorphosed manganese-rich......
terrigenous sediment
terrigenous sediment, deep-sea sediment transported to the oceans by rivers and wind from land sources. Terrigeneous......
teschenite
teschenite, coarse- to fine-grained, rather dark-coloured, intrusive igneous rock that occurs in sills (tabular......
Teshub
Teshub, in the religions of Asia Minor, the Hurrian weather god, assimilated by the Hittites to their own weather......
tetradymite
tetradymite, a sulfide mineral of bismuth and tellurium (Bi2Te2S). It is commonly found in gold-quartz veins and......
tetrahedrite
tetrahedrite, common sulfosalt mineral, an antimony sulfide of copper, iron, zinc, and silver [(Cu,Fe,Zn,Ag)12Sb4S13],......
texture
texture, in rocks, the size, shape, and arrangement (or fabric) of the mineral grains and crystals. Also important......
Thanetian Stage
Thanetian Stage, uppermost division of Paleocene rocks, representing all rocks deposited worldwide during the Thanetian......
The Perils of an Early Spring
Outside of the tropics, the spring season is a time of renewal as buds and leaves begin to sprout on trees and......
thenardite
thenardite, any of a type of sodium sulfate mineral (Na2SO4) that has been deposited as an evaporation product......
theralite
theralite, any member of a group of intrusive igneous rocks that contain labradorite (basic plagioclase feldspar),......
thermocline
thermocline, oceanic water layer in which water temperature decreases rapidly with increasing depth. A widespread......
thermohaline circulation
thermohaline circulation (THC), the component of general oceanic circulation controlled by horizontal differences......
thermonatrite
thermonatrite, a carbonate mineral, hydrated sodium carbonate (Na2CO3·H2O), found near saline lakes as an evaporation......
Thermosphere
Thermosphere, region of increasing temperature in Earth’s atmosphere that is located above the mesosphere. The......
tholeiite
tholeiite, fine-grained extrusive igneous rock, a basalt that contains plagioclase feldspar (labradorite), clinopyroxene......
thorianite
thorianite, thorium dioxide mineral (ThO2) that is very heavy, hard, and coloured dark gray to brownish black or......
thorite
thorite, thorium silicate, ThSiO4, one of the most important thorium minerals. Almost always altered by hydration,......
thunder
thunder, sound caused by a lightning discharge. Lightning heats the air in its path and causes a large over-pressure......
thunderstorm
thunderstorm, a violent short-lived weather disturbance that is almost always associated with lightning, thunder,......
tidal bore
tidal bore, body of water that, during exceptionally high sea tides, rushes up some rivers and estuaries near a......
tide
tide, any of the cyclic deformations of one astronomical body caused by the gravitational forces exerted by others.......
tillite
tillite, sedimentary rock that consists of consolidated masses of unweathered blocks (large, angular, detached......
Timeline of Climate Change
This infographic presents a timeline of climate change. A detailed description of this infographic appears below.......
tin
tin (Sn), a chemical element belonging to the carbon family, Group 14 (IVa) of the periodic table. It is a soft,......
tincalconite
tincalconite, a borate mineral, hydrated sodium tetraborate (Na2B4O5(OH)4·3H2O), that is found in nature only as......
tinguaite
tinguaite, pale- to dark-green, very fine-grained igneous rock that may be considered the dike (tabular body injected......
TIROS
TIROS, any of a series of U.S. meteorological satellites, the first of which was launched on April 1, 1960. The......
Titan
Titan, the largest moon of Saturn and the only moon in the solar system known to have clouds and a dense atmosphere.......
titanite
titanite, titanium and calcium silicate mineral, CaTiSiO4(O,OH,F), that, in a crystallized or compact form, makes......
Tithonian Stage
Tithonian Stage, uppermost of the three divisions of the Upper Jurassic Series, representing all rocks formed worldwide......
Toarcian Stage
Toarcian Stage, uppermost of the four divisions of the Lower Jurassic Series, representing all rocks formed worldwide......
Today in History—April 14: The Volcanic Eruption That Grounded a Continent
On this day in 2010, Iceland’s Eyjafjallajökull volcano erupted in earnest. Small earthquakes had been rumbling......
Today in History—August 24: A Buried City Keeps Surprising Us
We still have questions about the eruption of Mount Vesuvius that doomed Pompeii—even though the study of its site......
Today in History—February 2: The Weather-Watching Whistle-pig
On this day in 1887, in a town in western Pennsylvania that barely qualified as a town, a group from the local......
Today in History—January 5: A Winter So Cold It Rewrote History
On January 5, 1709, Europe’s coldest winter in 500 years crept in overnight. The chill stretched from England to......
Today in History—June 10: Benjamin Franklin Flies a Kite—and Makes History
Most people don’t see a thunderstorm and decide to fly a kite. But Benjamin Franklin was not most people. He was......
Today in History—March 29: A Woman Discovers Earth’s Core
The Danish seismologist who discovered Earth’s inner core built her theory using cardboard oatmeal boxes filled......
Tokyo-Yokohama earthquake of 1923
Tokyo-Yokohama earthquake of 1923, earthquake with a magnitude of 7.9 that struck the Tokyo-Yokohama metropolitan......
topaz
topaz, silicate mineral that is valued as a gemstone. It is believed that the topaz of modern mineralogists was......
torbernite
torbernite, hydrated copper uranate phosphate mineral, Cu(UO2)2(PO4)2·8–12H2O, that is one of the principal uranium-bearing......
tornado
tornado, a small-diameter column of violently rotating air developed within a convective cloud and in contact with......
Tortonian Stage
Tortonian Stage, division of middle Miocene rocks, representing all rocks deposited worldwide during the Tortonian......
tourmaline
tourmaline, borosilicate mineral of complex and variable composition. Three types of tourmaline, distinguished......
Tournaisian Stage
Tournaisian Stage, lowest and first of three intercontinental stages of the Mississippian Subsystem, Carboniferous......
trachyte
trachyte, light-coloured, very fine-grained extrusive igneous rock that is composed chiefly of alkali feldspar......
Trade wind
Trade wind, persistent wind that blows westward and toward the Equator from the subtropical high-pressure belts......
transform fault
transform fault, in geology and oceanography, a type of fault in which two tectonic plates slide past one another.......
travertine
travertine, dense, banded rock composed of calcite (calcium carbonate, CaCO3). Formed by the evaporation of river......
Tremadocian Stage
Tremadocian Stage, lowermost of the two standard worldwide divisions of the Lower Ordovician Series and lowest......
tridymite
tridymite, silica mineral, the stable form of silica (silicon dioxide, SiO2) at temperatures between 870° and 1,470°......
triphylite
triphylite, common phosphate mineral, lithium iron phosphate (LiFePO4), usually forming bluish or grayish, glassy......
triplite
triplite, phosphate mineral, consisting of manganese, iron, magnesium, and calcium phosphate [(Mn, Fe, Mg, Ca)2PO4(F,OH)].......
tripoli
tripoli, porous, friable, microcrystalline siliceous rock of sedimentary origin that is composed chiefly of chalcedony......
Triton
Triton, U.S. nuclear-powered submarine that was the first vessel to circumnavigate the globe underwater. The Triton......
troctolite
troctolite, coarse-grained, intrusive igneous rock that is composed almost entirely of olivine (often iron-rich)......
trona
trona, an evaporite mineral, hydrated sodium bicarbonate [Na3H(CO3)2·2H2O], occasionally encountered as a saline......
Tropical and subtropical desert climate
Tropical and subtropical desert climate, major climate type of the Köppen classification dominated in all months......
Tropical and subtropical steppe climate
Tropical and subtropical steppe climate, major climate type of the Köppen classification that occurs primarily......
tropical cyclone
tropical cyclone, an intense circular storm that originates over warm tropical oceans and is characterized by low......
Tropical monsoon and trade-wind littoral climate
Tropical monsoon and trade-wind littoral climate, major climate type of the Köppen classification characterized......
tropical storm
tropical storm, organized centre of low pressure that originates over warm tropical oceans. The maximum sustained......
Tropical wet-dry climate
Tropical wet-dry climate, major climate type of the Köppen classification characterized by distinct wet and dry......
Troposphere
Troposphere, lowest region of the atmosphere, bounded by the Earth beneath and the stratosphere above, with its......
tsunami
tsunami, catastrophic ocean wave, usually caused by a submarine earthquake, an underwater or coastal landslide,......
tuff
tuff, a relatively soft, porous rock that is usually formed by the compaction and cementation of volcanic ash or......
Tundra climate
Tundra climate, major climate type of the Köppen classification characterized by sub-freezing mean annual temperatures,......
turbidite
turbidite, a type of sedimentary rock composed of layered particles that grade upward from coarser to finer sizes......
turbidity current
turbidity current, underwater density current of abrasive sediments. Such currents appear to be relatively short-lived,......
Turonian Stage
Turonian Stage, second of six main divisions (in ascending order) in the Upper Cretaceous Series, representing......
turquoise
turquoise, hydrated copper and aluminum phosphate [CuAl6(PO4)4(OH)8·4H2O] that is extensively used as a gemstone.......
Twilight glow
Twilight glow, weak, widespread, and relatively steady glow from the sky that is observed around twilight; it is......
Typhon
Typhon, in Greek mythology, youngest son of Gaea (Earth) and Tartarus (of the nether world). He was described as......
tyuyamunite
tyuyamunite, radioactive, yellow, soft, and waxy uranium and vanadium oxide mineral, Ca(UO2)2(VO4)2·5–8H2O. It......
ulexite
ulexite, borate mineral, NaCaB5O6(ΟH)6·5H2O, that consists of hydrated sodium and calcium borate. Individual crystals......
Ultisol
Ultisol, one of the 12 soil orders in the U.S. Soil Taxonomy. Ultisols are reddish, clay-rich, acidic soils that......
umangite
umangite, a copper selenide (Cu3Se2) occurring only in small grains or fine granular aggregates with other copper......
Umbrisol
Umbrisol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......