Earth science

Kaharoa eruption (New Zealand, c. 1314) Kaharoa eruption A widespread tephra-producing eruption centered on the Tarawera area around 1314 CE. The Kaharoa ash layer is a key chronological marker for archaeology and environmental studies a…

Kammu Seamount (Kammu Guyot) Kammu Seamount Kammu Seamount, or Kammu Guyot, is an extinct flat-topped submarine volcano in the Hawaiian–Emperor seamount chain of the Pacific Ocean, named for the Japanese Emperor Kammu.

Kaolinite (kaolin): mineralogy, formation, uses and notable facts Kaolinite Kaolinite, commonly called kaolin or china clay, is a soft white clay mineral formed by the weathering of aluminous silicates. This article explains its structure, origin, industri…

Katabatic wind Katabatic winds are gravity-driven downslope flows of dense air. This entry explains their formation, physical mechanisms, common regional examples, impacts on weather and ecosyste…

Kelut (Kelud) — stratovolcano of eastern Java, Indonesia Kelut Kelut (also Kelud) is an active stratovolcano in eastern Java, Indonesia, known for its crater lake, explosive eruptions and lahars. It is closely monitored and has significant loc…

Kīlauea — active shield volcano of the Island of Hawaiʻi Kilauea Kīlauea is one of the most active volcanoes on Earth, a basaltic shield volcano on Hawaiʻi known for frequent lava flows, notable eruptions in 1983–2018, and important cultural and…

Kimmei Seamount — extinct volcano of the Hawaiian–Emperor chain Kimmei Seamount Kimmei Seamount is an extinct underwater volcano in the Emperor segment of the Hawaiian–Emperor chain in the Pacific Ocean, formed roughly 48–40 million years ago and named for a J…

Kimmeridge Clay Upper Jurassic organic-rich marine mudstone formation of western Europe; major petroleum source rock and important fossil-bearing unit named for exposures at Kimmeridge, Dorset.

Kōkō Guyot: Extinct Hawaiian–Emperor Seamount Dated 48 Million Years Ago Kōkō Seamount Kōkō Guyot is an extinct Pacific seamount in the Hawaiian–Emperor chain — a flat‑topped guyot shaped by erosion and subsidence, with radiometric dates indicating its last volcanism…

Kola Superdeep Borehole A Soviet scientific drilling project on Russia's Kola Peninsula that produced the deepest artificial point on Earth and yielded important data about continental crust structure and…

Köppen climate classification A widely used climate classification linking long‑term temperature and precipitation patterns to vegetation types; developed by Wladimir Köppen and later refined (Köppen–Geiger).

Krafla: volcanic caldera and geothermal system in northern Iceland Krafla Krafla is a volcanic caldera and active geothermal area in northern Iceland known for its fissure system, the Víti crater, historic eruptions in the 1970s–80s and nearby geothermal…

Kyushu–Palau Ridge Kyushu-Palau Ridge Undersea volcanic ridge in the Philippine Sea running southeast from Kyushu toward Palau. A remnant island-arc chain of extinct volcanoes studied for tectonics, seafloor geology an…

L'Atalante Basin A deep hypersaline brine pool in the eastern Mediterranean Sea, separated from surrounding water by a dense salt layer and notable for its extreme chemistry.

La Soufrière (Saint Vincent): overview, history and hazards La Soufrière (volcano) La Soufrière is an active stratovolcano on Saint Vincent, Caribbean. This article summarizes its geology, eruptive history, hazards, monitoring and significance to local communitie…

Labradorite — iridescent plagioclase feldspar prized for labradorescence Labradorite Labradorite is a calcium–sodium plagioclase feldspar known for its iridescent play of color (labradorescence). It occurs in igneous and metamorphic rocks and is used in jewelry and…

Lagerstätten: sites of exceptional fossil preservation Lagerstätten Lagerstätten are fossil sites with unusually detailed preservation. They include Konservat- and Konzentrat-Lagerstätten and provide rare windows into soft tissues, behavior, and wh…

Lakagígar (Laki): the 1783–84 fissure crater system in Iceland Lakagigar Lakagígar (Laki) is a 25 km row of volcanic craters in southern Iceland, source of the 1783–84 Laki eruption that produced vast basaltic flows and widespread environmental and huma…

Lake Agassiz: Ice‑Age Proglacial Lake of Central North America Lake Agassiz Former proglacial lake that covered much of central North America after the last ice age; shaped landscapes, soils and drainage and is studied for its climatic and geological impac…

Lake retention time (residence time) Lake retention time Average time water or a dissolved substance remains in a lake; calculated as lake volume divided by flow and used to assess pollutant fate, nutrient cycling, and water management.

Lake Superior agate: origin, features, and significance Lake Superior agate A banded, iron-stained agate found around Lake Superior. Discusses its formation in volcanic rock, glacial distribution, identifying features, collecting, uses in lapidary work, an…

Land (geography, characteristics and uses) Land Overview of land as the terrestrial portion of Earth: definitions, physical features, formation, uses, legal and cultural importance, and how land differs from water and other envi…

Landfall in Meteorology: definition, impacts and distinctions Landfall (meteorology) When a tropical system moves from sea to shore. Explains what counts as landfall, typical hazards (surge, wind, rain), how it differs from a direct hit, and preparedness considerat…

Landslide: Causes, Types, Mechanics, Impacts and Management Landslide Comprehensive overview of landslides covering definitions, types, common triggers, mechanics, monitoring, risk reduction, and practical mitigation and emergency measures.

Lapis lazuli: blue metamorphic gemstone and historic pigment Lapis lazuli Lapis lazuli is a deep-blue metamorphic rock used as a gemstone and historically as the source of ultramarine pigment. It contains lazurite, pyrite flecks and calcite and has been…

Laurentia — the ancient craton at the heart of North America Laurentia Laurentia is the ancient continental craton forming the geological core of North America and Greenland, composed of very old igneous and metamorphic rocks and shaped by billion-yea…

Laurussia (Euramerica): the Old Red Sandstone continent Laurussia Laurussia, also called Euramerica or the Old Red Sandstone Continent, was a late Paleozoic landmass formed by the collision of Laurentia, Baltica and Avalonia, shaping early terres…

Lava: molten rock that erupts and flows on Earth's surface Lava Lava is molten rock expelled onto the Earth's surface during volcanic activity. This article explains how lava forms, its common types, hazards, and why scientists study it.

Lava dome A lava dome is a steep, rounded volcanic mound formed by the slow extrusion of highly viscous lava; it poses collapse and explosive hazards and offers insight into magma compositio…

Leeward slope The leeward slope of a mountain is the side sheltered from prevailing winds. It commonly differs from the windward side in climate, vegetation, snow and human use because of orogra…

Length of day The length of a day is the time Earth or another body takes to rotate once relative to the Sun or the stars. This article explains solar and sidereal days, planetary differences, a…

Limestone: composition, formation, varieties, and uses Limestone Limestone is a common sedimentary rock composed mainly of calcium carbonate (calcite). It forms from biological activity and chemical precipitation and is important as a building m…

Limnology: the scientific study of inland waters Limnology Limnology is the multidisciplinary science of inland aquatic systems — lakes, rivers, wetlands and groundwater — covering their physical, chemical, biological and geological dynami…

Limonite Limonite is a general name for hydrated iron oxide materials—an earthy, yellow-brown to black mixture often formed by weathering and used historically as an iron ore and pigment.

List of earthquakes Overview of how lists of earthquakes are compiled, scales used to describe magnitude and intensity, historical challenges, notable examples, and criteria for inclusion.

List of extinction events and their significance List of extinction events Overview of Earth's major extinction events, their identification in the fossil record, likely causes, and the evolutionary and ecological consequences, including relevance to toda…

List of minerals Overview of mineral species: classification, key properties, formation processes, common examples, uses, and how minerals differ from rocks.

List of Pacific typhoon seasons Annual compilations of tropical cyclone activity in the western North Pacific, which is monitored year‑round and documented as individual seasonal lists for each calendar year.

List of tectonic plates: major, minor and microplates List of tectonic plates Overview and examples of Earth's tectonic plates, including commonly recognized major plates, examples of minor and microplates, boundary types, motion, and their geological signif…

List of volcanoes: overview, classification, distribution and notable examples List of volcanoes An organized overview of volcano lists: categories (active, dormant, extinct), common types, global distribution, notable examples, hazards, monitoring and how volcano inventories…

Lithosphere The lithosphere is Earth's rigid outer shell — the crust plus the uppermost solid mantle — that forms tectonic plates and controls earthquakes, volcanism, and continental structure…

Little Ice Age: cooler climate and its impacts from late medieval to 19th century Little Ice Age A sustained period of cooler climate affecting parts of the Northern Hemisphere between roughly the 14th–19th centuries, marked by glacier advance, colder winters and regional vari…

Littoral zone: shoreward habitats and ecological role Littoral zone The littoral zone is the nearshore area of seas, lakes and rivers where land and water meet; it includes intertidal areas, supports diverse communities, and plays key ecological an…

Live Earth: the 2007 global concert series for climate awareness Live Earth Live Earth was a worldwide series of benefit concerts on July 7, 2007, organized to raise public awareness about climate change through live performances on every continent.

Lō'ihi Seamount An active submarine volcano southeast of the island of Hawaiʻi, Lō'ihi is the youngest member of the Hawaiian–Emperor seamount chain and a key site for studying submarine volcanism…

Long Valley Caldera (Eastern California) Long Valley Caldera A large volcanic caldera in eastern California formed by a massive eruption 760,000 years ago. Known for the Bishop Tuff, geothermal activity, seismic unrest and nearby Mammoth Mou…

Longshore drift (littoral drift): coastal transport of sediment Longshore drift Longshore drift is the zigzag movement of sand and pebbles along a shoreline driven by oblique wave approach, shaping beaches and coastal landforms and influencing erosion and mana…

Loop Current (Gulf of Mexico): overview, behavior and significance Loop Current The Loop Current is a warm, seawater current in the Gulf of Mexico that feeds the Florida Current and Gulf Stream. It produces large warm-core eddies and influences weather, ecosys…