Earth Science, Geologic Time & Fossils, SMI-TAE

Planet Earth has billions of years of history, from the time when it was an inhospitable ball of hot magma to when its surface stabilized into a variety of diverse zones capable of supporting many life-forms. Many are the species that lived through the various geologic eras and left a trace of their existence in the fossils that we study today. But Earth is never done settling, as we can see from the earthquakes, tsunamis, volcanic eruptions, and other phenomena manifested in Earth’s crust, oceans, and atmosphere.
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Earth Science, Geologic Time & Fossils Encyclopedia Articles By Title

smithsonite
smithsonite, zinc carbonate (ZnCO3), a mineral that was the principal source of zinc until the 1880s, when it was......
snow
snow, the solid form of water that crystallizes in the atmosphere and, falling to the Earth, covers, permanently......
snow and ice climate
snow and ice climate, major climate type of the Köppen classification characterized by bitterly cold temperatures......
Snowball Earth hypothesis
Snowball Earth hypothesis, in geology and climatology, an explanation first proposed by American geobiologist J.L.......
soil chemistry
soil chemistry, discipline embracing all chemical and mineralogical compounds and reactions occurring in soils......
soil liquefaction
soil liquefaction, ground failure or loss of strength that causes otherwise solid soil to behave temporarily as......
soil mechanics
soil mechanics, the study of the physical properties and utilization of soils, especially used in planning foundations......
solar system
solar system, assemblage consisting of the Sun—an average star in the Milky Way Galaxy—and those bodies orbiting......
Solo man
Solo man, prehistoric human known from 11 fossil skulls (without facial skeletons) and 2 leg-bone fragments that......
Solonchak
Solonchak, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
Solonetz
Solonetz, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
Sorby, Henry Clifton
Henry Clifton Sorby was an English geologist whose microscopic studies of thin slices of rock earned him the title......
sorosilicate
sorosilicate, any member of a group of compounds with structures that have two silicate tetrahedrons (each consisting......
South Pole
South Pole, the southern end of the Earth’s axis, lying in Antarctica, about 300 miles (480 km) south of the Ross......
southern lights
southern lights, luminous atmospheric display visible in the Southern Hemisphere. See...
Southern Oscillation
Southern Oscillation, in oceanography and climatology, a coherent interannual fluctuation of atmospheric pressure......
Spalacotherium
Spalacotherium, extinct genus of primitive, probably predaceous, mammals known from fossils found in European deposits......
specific humidity
specific humidity, mass of water vapour in a unit mass of moist air, usually expressed as grams of vapour per kilogram......
speleology
speleology, scientific discipline that is concerned with all aspects of caves and cave systems. Exploration and......
sphalerite
sphalerite, zinc sulfide (ZnS), the chief ore mineral of zinc. It is found associated with galena in most important......
spherical Earth
spherical Earth, refers to any figure of Earth as represented by a sphere. Although other models, including the......
spherulite
spherulite, spherical body generally occurring in glassy rocks, especially silica-rich rhyolites. Spherulites frequently......
spilite
spilite, fine-grained or dense, extrusive igneous (volcanic) rock that is usually free of visible crystals and......
spiny shark
spiny shark, any of a group of more than 150 species of small extinct fishes traditionally classified in the class......
Spodosol
Spodosol, one of the 12 soil orders in the U.S. Soil Taxonomy. Spodosols are ashy gray, acidic soils with a strongly......
spreading centre
spreading centre, in oceanography and geology, the linear boundary between two diverging lithospheric plates on......
spring
spring, in climatology, season of the year between winter and summer during which temperatures gradually rise.......
spring tide
spring tide, tide of maximal range, near the time of new and full moon when the Sun and Moon are in syzygy—i.e.,......
squall
squall, as used by weather forecasters, a sudden wind-speed increase of 8 metres per second (18 miles per hour)......
St. Swithin’s Day
St. Swithin’s Day, (July 15), a day on which, according to folklore, the weather for a subsequent period is dictated.......
Stagg, James Martin
James Martin Stagg was a British meteorologist who, as the chief weather forecaster to General Dwight D. Eisenhower,......
standard atmosphere
standard atmosphere, atmospheric model with a given vertical distribution of temperature, pressure, and humidity,......
stannite
stannite, a sulfide mineral, chemical formula Cu2FeSnS4, that is an ore of tin. It is ordinarily found associated......
staurolite
staurolite, silicate mineral [(Fe,Mg,Zn)3-4Al18Si8O48H2-4] produced by regional metamorphism in rocks such as mica......
stegosaur
stegosaur, any of the plated dinosaur species, including Stegosaurus and Tuojiangosaurus of the Late Jurassic period......
Steneosaurus
Steneosaurus, (genus Steneosaurus), extinct crocodiles that inhabited shallow seas and whose fossils are found......
Steno, Nicolaus
Nicolaus Steno was a geologist and anatomist whose early observations greatly advanced the development of geology.......
stephanite
stephanite, a sulfosalt mineral, silver antimony sulfide (Ag5SbS4), that occurs as black, lustrous, orthorhombic......
Stewart, Balfour
Balfour Stewart was a Scottish meteorologist and geophysicist noted for his studies of terrestrial magnetism and......
stibnite
stibnite, antimony sulfide (Sb2S3), the principal ore of antimony. This mineral has a brilliant metallic lustre,......
Stommel, Henry Melson
Henry Melson Stommel was an American oceanographer and meteorologist. Stommel became internationally known during......
Stoney, George Johnstone
George Johnstone Stoney was a physicist who introduced the term electron for the fundamental unit of electricity.......
storm
storm, violent atmospheric disturbance, characterized by low barometric pressure, cloud cover, precipitation, strong......
Strabo
Strabo was a Greek geographer and historian whose Geography is the only extant work covering the whole range of......
Strachey, John
John Strachey was an early geologist who was the first to suggest the theory of stratified rock formations. He......
stratification
stratification, the layering that occurs in most sedimentary rocks and in those igneous rocks formed at the Earth’s......
stratigraphy
stratigraphy, scientific discipline concerned with the description of rock successions and their interpretation......
stratosphere
stratosphere, layer of Earth’s atmosphere lying between the troposphere and the mesosphere. The lower portion of......
stratospheric sulfur injection
stratospheric sulfur injection, untested geoengineering technique designed to scatter incoming solar radiation......
stratovolcano
stratovolcano, volcanic landform characterized by a conical shape formed by layers of volcanic material deposited......
stratum
stratum, sedimentary rock layer bounded by two stratification planes, the latter being produced by visible changes......
streak
streak, the colour of a mineral in its powdered form. It is usually obtained by rubbing the mineral on a hard,......
strengite
strengite, phosphate mineral similar to variscite (q.v.) with the chemical formula...
Streptelasma
Streptelasma, extinct genus of corals, existing as single animals rather than colonial forms and found as fossils......
strike
strike, in geology, direction of the line formed by the intersection of a fault, bed, or other planar feature and......
strike-slip fault
strike-slip fault, in geology, a fracture in the rocks of Earth’s crust in which the rock masses slip past one......
Stringocephalus
Stringocephalus, extinct genus of large brachiopods, or lamp shells, found as fossils in Devonian marine rocks......
stromatolite
stromatolite, layered deposit, mainly of limestone, formed by the growth of blue-green algae (primitive one-celled......
Stromatoporida
Stromatoporida, extinct order of corals found as fossils in marine rocks of Cambrian to Cretaceous age (542 million......
stromeyerite
stromeyerite, a sulfide mineral of copper and silver (CuAgS) that occurs as compact masses with copper and lead......
strontianite
strontianite, a strontium carbonate mineral (SrCO3) that is the original and principal source of strontium. It......
Stropheodonta
Stropheodonta, genus of small, extinct brachiopods (lamp shells) found as fossils in Devonian marine rocks (those......
Strophomena
Strophomena, genus of extinct brachiopods (lamp shells) found as fossils in Middle and Upper Ordovician marine......
structural geology
structural geology, scientific discipline that is concerned with rock deformation on both a large and a small scale.......
Struthiomimus
Struthiomimus, (genus Struthiomimus), ostrichlike dinosaurs found as fossils from the Late Cretaceous Period (99......
stylolite
stylolite, secondary (chemical) sedimentary structure consisting of a series of relatively small, alternating,......
subduction zone
subduction zone, oceanic trench area marginal to a continent in which, according to the theory of plate tectonics,......
subpolar gyre
subpolar gyre, an area of cyclonic ocean circulation that sits beneath a persistent region of low atmospheric pressure.......
subsidence
subsidence, sinking of the Earth’s surface in response to geologic or man-induced causes. When subsidence occurs......
subsoil
subsoil, Layer (stratum) of earth immediately below the surface soil, consisting predominantly of minerals and......
subtropical gyre
subtropical gyre, an area of anticyclonic ocean circulation that sits beneath a region of subtropical high pressure.......
subtropical high
subtropical high, one of several regions of semipermanent high atmospheric pressure located over the oceans between......
Sue
Sue, nickname for one of the most complete and best-preserved skeletons of Tyrannosaurus rex. The fossil was dated......
Suess, Eduard
Eduard Suess was an Austrian geologist who helped lay the basis for paleogeography and tectonics—i.e., the study......
sulfate mineral
sulfate mineral, any naturally occurring salt of sulfuric acid. About 200 distinct kinds of sulfates are recorded......
sulfide mineral
sulfide mineral, any member of a group of compounds of sulfur with one or more metals. Most of the sulfides are......
sulfosalt
sulfosalt, any of an extensive group of minerals, mostly rare species, marked by some of the most complicated atomic......
sulfur
sulfur (S), nonmetallic chemical element belonging to the oxygen group (Group 16 [VIa] of the periodic table),......
Sullivan, Kathryn
Kathryn Sullivan is an American oceanographer and astronaut, the first American woman to walk in space (1984).......
summer
summer, warmest season of the year, between spring and autumn. In the Northern Hemisphere, it is usually defined......
sun dog
sun dog, atmospheric optical phenomenon appearing in the sky as luminous spots 22° on each side of the Sun and......
supercontinent
supercontinent, large landmass that accounts for the vast majority of Earth’s land. Some researchers argue that......
superposition, law of
law of superposition, a major principle of stratigraphy stating that within a sequence of layers of sedimentary......
surge
surge, in meteorology, an atmospheric process that operates on oceans and inland waters whereby a change in atmospheric......
sussexite
sussexite, white to straw-yellow borate mineral, basic manganese borate [MnBO2(OH)]. Magnesium replaces manganese......
svabite
svabite, arsenate mineral, calcium fluoride arsenate [Ca5(AsO4)3F], in the apatite group of phosphates. Typical......
Sverdrup, Harold Ulrik
Harold Ulrik Sverdrup was a Norwegian meteorologist and oceanographer known for his studies of the physics, chemistry,......
syenite
syenite, any of a class of intrusive igneous rocks essentially composed of an alkali feldspar and a ferromagnesian......
sylvanite
sylvanite, a gold and silver telluride mineral [(Au,Ag)Te2] in which the ratio of gold to silver atoms is commonly......
sylvite
sylvite, halide mineral, potassium chloride (KCl), the chief source of potassium. It is rarer than halite (sodium......
Symons, George James
George James Symons was a British meteorologist who strove to provide reliable observational data by imposing standards......
szaibelyite
szaibelyite, mineral composed of basic magnesium borate [MgBo2(OH)], similar to the manganese mineral sussexite...
T.H. Huxley on evolution and biology
Although his formal education occurred between the ages of 8 and 10, plus four or five years at medical school,......
Tabulata
Tabulata, major division of extinct coral animals found as fossils in Ordovician to Jurassic marine rocks (488......
Tabūn
Tabūn, site of paleoanthropological excavations in a deep rock shelter located on the edge of Mount Carmel and......
tachylyte
tachylyte, glassy igneous rocks low in silica, such as basalt or diabase. Tachylytes are black with a pitchlike......
taeniodont
taeniodont, any member of an extinct suborder (Taeniodonta) of mammals that lived in North America throughout the......
taenite
taenite, nickel-iron mineral having a face-centred cubic structure and playing a major role in the crystallization......

Earth Science, Geologic Time & Fossils Encyclopedia Articles By Title