Earth Science, Geologic Time & Fossils, IRI-LIM
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.
Earth Science, Geologic Time & Fossils Encyclopedia Articles By Title
iridosmine
iridosmine, mineral consisting of an alloy of iridium and a smaller proportion of osmium. It occurs in gold-bearing......
Irish elk
Irish elk, (Megaloceros giganteus), extinct species of deer, characterized by immense body size and wide antlers,......
iron
iron (Fe), chemical element, metal of Group 8 (VIIIb) of the periodic table, the most-used and cheapest metal.......
Is Climate Change Real?
By definition, climate change is the periodic modification of Earth’s climate due to changes in the atmosphere......
Is diamond the hardest substance on Earth?
Yes, diamond is the hardest naturally occurring substance on Earth. It is a 10 on the Mohs scale of mineral hardness,......
Is Earth Going to Change the Direction in Which It Rotates?
It’s not likely, but there are things that could stop Earth’s rotation and get it moving in the other direction.......
Is the Ozone Layer Finally Healing Itself?
Earth is currently experiencing a host of environmental problems. Air and water pollution continue to plague much......
Iselin, Columbus O’D.
Columbus O’D. Iselin was an American oceanographer who, as director of the Woods Hole Oceanographic Institution......
island arc
island arc, long, curved chain of oceanic islands associated with intense volcanic and seismic activity and orogenic......
isostasy
isostasy, ideal theoretical balance of all large portions of Earth’s lithosphere as though they were floating on......
Isotelus
Isotelus, genus of trilobites (extinct arthropods) restricted to Europe and North America during the Ordovician......
Jackson, Charles Thomas
Charles Thomas Jackson was an American physician, chemist, and pioneer geologist and mineralogist. Jackson received......
Japan earthquake and tsunami of 2011
Japan earthquake and tsunami of 2011, severe natural disaster that occurred in northeastern Japan on March 11,......
Jet stream
Jet stream, a region of long, narrow, high-speed winds that typically flow northeastward, eastward, and southeastward......
John Day Fossil Beds National Monument
John Day Fossil Beds National Monument, series of rock formations in north-central Oregon, U.S., consisting of......
joint
joint, in geology, a brittle-fracture surface in rocks along which little or no displacement has occurred. Present......
Joly, John
John Joly was an Irish geologist and physicist who, soon after 1898, estimated the age of the Earth at 100,000,000......
Jones, Brian
Brian Jones is a British aviator who on March 20, 1999, with captain Bertrand Piccard, completed the first nonstop......
Jurassic Period
Jurassic Period, second of three periods of the Mesozoic Era. Extending from 201.3 million to 145 million years......
Kabwe cranium
Kabwe cranium, fossilized skull of an extinct human species (genus Homo) found near the town of Kabwe, Zambia (formerly......
Kahramanmaraş earthquake of 2023
Kahramanmaraş earthquake of 2023, an earthquake and a severe aftershock that struck near the border separating......
kainite
kainite, a naturally occurring double salt, hydrated potassium and magnesium sulfate-chloride, KMgSO4Cl·3H2O. It......
Kamacite
Kamacite, mineral consisting of iron alloyed with 5–7 percent nickel by weight and found in almost all meteorites......
kaolin
kaolin, soft white clay that is an essential ingredient in the manufacture of china and porcelain and is widely......
kaolisol
kaolisol, soil that is formed under the heat and heavy rainfall of the tropics, which leaches out the silica and......
Kashmir earthquake of 2005
Kashmir earthquake of 2005, disastrous earthquake that occurred on October 8, 2005, in the Pakistan-administered......
Kastanozem
Kastanozem, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
Kayser, Heinrich
Heinrich Kayser was a German physicist who discovered the presence of helium in the Earth’s atmosphere. Kayser’s......
Kebara
Kebara, paleoanthropological site on Mount Carmel in northern Israel that has yielded a trove of Neanderthal bones......
Keeling Curve
Keeling Curve, graph showing seasonal and annual changes in atmospheric carbon dioxide (CO2) concentrations since......
Kelvin, William Thomson, Baron
William Thomson, Baron Kelvin was a Scottish engineer, mathematician, and physicist who profoundly influenced the......
kernite
kernite, borate mineral, hydrated sodium borate (Na2B4O7·4H2O), that was formerly the chief source of borax (q.v.).......
Keweenawan System
Keweenawan System, division of late Precambrian rocks and time in North America (the Precambrian began about 4.6......
Kidston, Robert
Robert Kidston was an English paleobotanist, noted for his discoveries and descriptions of plant fossils from the......
kieserite
kieserite, a sulfate mineral, hydrated magnesium sulfate (MgSO4·H2O), that is abundant in evaporite deposits. It......
kimberlite
kimberlite, a dark-coloured, heavy, often altered and brecciated (fragmented), intrusive igneous rock that contains......
kimberlite eruption
kimberlite eruption, small but powerful volcanic eruption caused by the rapid ascent of kimberlites—a type of intrusive......
King, Clarence
Clarence King was an American geologist and mining engineer who organized and directed the U.S. Geological Survey......
Kircher, Athanasius
Athanasius Kircher was a Jesuit priest and scholar, sometimes called the last Renaissance man, important for his......
Kirwan, Richard
Richard Kirwan was an Irish chemist known for his contributions in several areas of science. Kirwan, who was born......
Knowlton, Frank Hall
Frank Hall Knowlton was a U.S. paleobotanist and pioneer in the study of prehistoric climates based on geologic......
Koro Toro
Koro Toro, site of paleoanthropological excavations in central Chad, best known for a fossilized fragment of a......
Kotzebue, Otto von
Otto von Kotzebue was a Russian naval officer who completed three circumnavigations of the Earth, charted much......
Kozyrev, Nikolay Aleksandrovich
Nikolay Aleksandrovich Kozyrev was a Russian astronomer, who claimed to have discovered volcano-like activity on......
Krapina remains
Krapina remains, fossilized remains of at least 24 early Neanderthal adults and children, consisting of skulls,......
KREEP
KREEP, a suite of lunar lavas, relatively enriched in certain elements, that were identified in the analysis of......
krennerite
krennerite, a gold mineral that usually occurs in veins formed at low temperatures, as at Kalgoorlie, Australia,......
Krusenstern, Adam Johann
Adam Johann Krusenstern was a naval officer who commanded the first Russian expedition to explore the Pacific Ocean......
Kuiper, Gerard Peter
Gerard Peter Kuiper was a Dutch-American astronomer known especially for his discoveries and theories concerning......
kutnohorite
kutnohorite, a carbonate mineral, calcium manganese carbonate [CaMn(CO3)2]. Confirmed as a naturally occurring......
Kármán line
Kármán line, boundary separating Earth’s atmosphere and outer space. The line is neither sharp nor well defined......
Kâtip Çelebi
Kâtip Çelebi was a Turkish historian, geographer, and bibliographer. Kâtip became an army clerk and took part in......
Köppen climate classification
Köppen climate classification, widely used, vegetation-based, empirical climate classification system developed......
Köppen, Wladimir
Wladimir Köppen was a German meteorologist and climatologist best known for his delineation and mapping of the......
Kōbe earthquake of 1995
Kōbe earthquake of 1995, (Jan. 17, 1995) large-scale earthquake in the Ōsaka-Kōbe (Hanshin) metropolitan area of......
La Brea Tar Pits
La Brea Tar Pits, tar (Spanish brea) pits, in Hancock Park (Rancho La Brea), Los Angeles, California, U.S. The......
La Chapelle-aux-Saints
La Chapelle-aux-Saints, cave site near the village of La Chapelle-aux-Saints in central France where the bones......
La Ferrassie
La Ferrassie, paleoanthropological site in the Dordogne region of France where Neanderthal fossils were found in......
La Niña
La Niña, the cool phase of El Niño and the Southern Oscillation (ENSO), characterized primarily by colder-than-normal......
laccolith
laccolith, in geology, any of a type of igneous intrusion that has split apart two strata, resulting in a domelike......
Lacroix, Alfred
Alfred Lacroix was a French mineralogist whose Minéraux des roches (1888; “The Minerals of Rocks”), written with......
Lagar Velho
Lagar Velho, site near Leiria, central Portugal, where the buried skeleton of a four-year-old child, dating to......
lahar
lahar, mudflow of volcanic material. Lahars may carry all sizes of material from ash to large boulders and produce......
lake
lake, any relatively large body of slowly moving or standing water that occupies an inland basin of appreciable......
- Introduction
- Uses, Abuses, Conservation
- Tectonism, Volcanism, Landslides
- Glacial Basins, Formation, Ecosystems
- Sedimentation, Erosion, Deposition
- Salinity, Nutrients, Oxygen
- Sulfates, Nitrates, Phosphates
- Vertical Mixing, Overturn, Stratification
- Currents, Circulation, Ecosystems
- Surface Waves, Circulation, Ecosystems
- Seiches, Standing Waves, Oscillations
- Wave, Current, Erosion
- Hydrology, Balance, Ecosystems
- Extinction, Ecosystems, Pollution
- World's Largest, Types, Ecosystems
Lamont, Johann von
Johann von Lamont was a Scottish-born German astronomer noted for discovering that the magnetic field of the Earth......
lamprophyre
lamprophyre, any of a group of dark gray to black intrusive igneous rocks that generally occur as dikes (tabular......
Lance Formation
Lance Formation, division of rocks in the western United States dating to the end of the Cretaceous Period 65.5......
Langley, Samuel Pierpont
Samuel Pierpont Langley was an American astrophysicist and aeronautical pioneer who developed new instruments with......
lapillus
lapillus, unconsolidated volcanic fragment with a diameter between 4 and 32 mm (0.16 and 1.26 inches) that was......
lapis lazuli
lapis lazuli, semiprecious stone valued for its deep blue colour. The source of the pigment ultramarine (q.v.),......
Lapworth, Charles
Charles Lapworth was an English geologist who proposed what came to be called the Ordovician Period (about 488......
Larsen Ice Shelf
Larsen Ice Shelf, ice shelf in the northwestern Weddell Sea, adjoining the east coast of the Antarctic Peninsula......
Lartet, Édouard
Édouard Lartet was a French geologist, archaeologist, and a principal founder of paleontology. He is credited chiefly......
last glacial maximum
last glacial maximum (LGM), the most recent geologic interval, which spanned 29,000 to 19,000 years ago, in which......
laterite
laterite, soil layer that is rich in iron oxide and derived from a wide variety of rocks weathering under strongly......
latite
latite, extrusive igneous rock very abundant in western North America. Usually coloured white, yellowish, pinkish,......
latitude and longitude
latitude and longitude, in cartography, a coordinate system used to determine and describe the position of any......
Laurasia
Laurasia, ancient continental mass in the Northern Hemisphere that included North America, Europe, and Asia (except......
lava
lava, magma (molten rock) emerging as a liquid onto Earth’s surface. The term lava is also used for the solidified......
lazulite
lazulite, phosphate mineral, a basic magnesium and aluminum phosphate [MgAl2 (PO4)2(OH)2], that often occurs as......
Le Moustier
Le Moustier, paleoanthropological and archaeological site in the Dordogne region of southwestern France that has......
leaching
leaching, in geology, loss of soluble substances and colloids from the top layer of soil by percolating precipitation.......
lead
lead (Pb), a soft, silvery white or grayish metal in Group 14 (IVa) of the periodic table. Lead is very malleable,......
Leake, William Martin
William Martin Leake was a British army officer, topographer, and antiquary whose surveys of ancient Greek sites......
Leakey, Louis
Louis Leakey was a Kenyan archaeologist and anthropologist, a member of the distinguished Leakey family of scholars......
Lebachia
Lebachia, a genus of extinct cone-bearing plants known from fossils of the Late Carboniferous and Early Permian......
Lee cyclone
Lee cyclone, small-scale cyclone that forms on the leeward, or downwind, side of mountain barriers as the general......
Lee wave
Lee wave, vertical undulation of airstreams on the lee side of a mountain. (The lee side is the side that is downstream......
Lehmann, Johann Gottlob
Johann Gottlob Lehmann was a German geologist who contributed to the development of stratigraphy, the scientific......
Leidy, Joseph
Joseph Leidy was a zoologist, one of the most distinguished and versatile scientists in the United States, who......
Lepidodendron
Lepidodendron, extinct genus of tree-sized lycopsid plants that lived during the Carboniferous Period (about 359......
Leptaena
Leptaena, genus of extinct brachiopods (lamp shells) commonly found as fossils in Ordovician to Lower Carboniferous......
Leptodesma
Leptodesma, extinct genus of pelecypods (clams) found as fossils in Silurian to Lower Carboniferous rocks (between......
Leptodus
Leptodus, extinct genus of articulate brachiopods, or lamp shells, of the Permian Period (299 million to 251 million......
Leptolepis
Leptolepis, genus of marine fishes very closely related to the first teleosts, the dominant group of fishes in......
Leptosol
Leptosol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
leucitite
leucitite, extrusive igneous rock, coloured ash gray to nearly black, that contains leucite and augite as large,......
Li Zhizao
Li Zhizao was a Chinese mathematician, astronomer, and geographer whose translations of European scientific books......
lightning
lightning, the visible discharge of electricity that occurs when a region of a cloud acquires an excess electrical......
limburgite
limburgite, dark-coloured volcanic rock that resembles basalt but normally contains no feldspar. It is associated......