Earth science

Vaalbara: Earth's earliest proposed supercontinent Vaalbara Vaalbara is a hypothesized Archaean supercontinent composed of the Kaapvaal and Pilbara cratons; its study illuminates early continental growth, ancient geology, and the conditions…

Variscan (Hercynian) orogeny: late Palaeozoic mountain building and its remnants Variscan orogeny A major late Palaeozoic orogenic episode produced when Gondwana collided with Laurussia to help form Pangaea. Its folded belts and intrusions shaped many European, North African an…

Vermiculite: properties, uses, history and safety Vermiculite Vermiculite is a layered silicate mineral that expands when heated. It is used for insulation, horticulture, packaging and fireproofing; some deposits may contain asbestos and requ…

Villarrica (volcano) Villarrica is one of Chile's most active stratovolcanoes, near Lake Villarrica and the towns of Villarrica and Pucón. It features a persistent lava lake, frequent eruptions, and ac…

Volcanic belt A volcanic belt is an extensive region of concentrated volcanic activity, typically aligned with plate boundaries or mantle plumes, important for geology, hazards, and resource dis…

Volcanic eruption: causes, types, hazards and global significance Volcanic eruption A volcanic eruption releases molten rock, ash and gases from beneath Earth’s crust. This article explains mechanisms, eruption styles, hazards, monitoring and the geological and so…

Volcanic Explosivity Index (VEI) Volcanic Explosivity Index A concise guide to the Volcanic Explosivity Index: what it measures, how the 0–8 scale works, its origin, common uses, well-known examples, and limitations of the index.

Volcanic plug: formation, features, and landscape significance Volcanic plug A volcanic plug (neck or puy) forms when magma solidifies within a volcanic conduit; erosion later exposes the resistant core, creating prominent landforms with distinct hazards an…

Volcanic winter: global cooling from very large volcanic eruptions Volcanic winter Extended global cooling caused when major volcanic eruptions inject ash and sulfur gases into the stratosphere, forming aerosols that reduce sunlight and alter climate, ecosystems…

Volcanism: processes, types, hazards and significance Volcanism Volcanism is the set of processes by which molten rock, gases and solid fragments reach or affect the Earth's surface. This article covers causes, eruption types, volcano forms, ha…

Volcano: formation, structure, eruption types, hazards and examples Volcano An overview of volcanoes: how they form, the materials and structures involved, major types and examples, impacts on people and climate, and how scientists monitor them.

Volcanoes of Iceland: geology, activity, and notable eruptions Volcanoes in Iceland Iceland sits on the Mid‑Atlantic Ridge and a mantle hotspot, producing around 30 active volcanic systems. This article explains causes, eruption types, hazards, history and notable…

Volcanoes of Kamchatka Comprehensive overview of the Kamchatka Peninsula volcanic province: geology, notable cones, geothermal areas, hazards, ecology, UNESCO protection, monitoring and visitor considera…

Volcanology: the science of volcanoes, magma, lava and eruptions Volcanology Volcanology is the branch of geology that investigates volcanoes, magmatic processes, erupted materials and volcanic hazards. It combines fieldwork, laboratory analysis and monitor…

Vredefort crater (Vredefort Dome) — Earth's largest confirmed impact structure Vredefort crater The Vredefort crater in South Africa is the largest confirmed meteorite impact structure on Earth, centered on the Vredefort Dome. It is an ancient, deeply eroded site of major geo…

Water: properties, states, cycle, and role in Earth's systems Water Comprehensive overview of water (H₂O): its physical and chemical properties, states and phase changes, distribution on Earth, role in the water cycle, importance for life, and comm…

Water content (soil moisture and pore water) Water content Water content is the proportion of water held in a porous material such as soil, expressed by mass or volume. It affects plant growth, groundwater movement, civil engineering and e…

Water cycle (hydrological cycle) Water cycle The continuous circulation of water through Earth's atmosphere, surface, and subsurface: processes, origin, importance for climate and life, and human impacts on its balance.

Water on Mars: distribution, evidence, and significance Water on Mars Summary of the forms, geological evidence, history and modern implications of water on Mars, and how spacecraft observations have revealed ice, hydrated minerals and transient flow…

Water table: definition, behavior, and significance in groundwater systems Water table The water table is the upper surface of saturated ground. This article explains what it is, how it moves, what controls it, and why it matters for wells, ecosystems, and constructi…

Waterspout A waterspout is a rotating column of air and condensed water over a body of water. This article explains its types, formation, appearance, hazards, and how it differs from land tor…

Weather: Causes, Elements, Measurement, Forecasting and Impacts Weather Concise encyclopedia entry on weather: definition, main phenomena, measurement instruments, forecasting methods, impacts of severe events, and links to observation networks and pre…

Weather balloon (sounding balloon) Weather balloon A weather balloon is a free-flying high-altitude platform that carries instruments to measure atmospheric pressure, temperature, humidity and winds for forecasting and research.

Weather forecast: how forecasts are made, used, and interpreted Weather forecast A weather forecast predicts future atmospheric conditions using observations, models, and human judgment. This article explains data sources, methods, accuracy limits, typical prod…

Weather station: instruments, history, and practical uses Weather station An overview of weather stations: what they measure, common instruments, brief history, types, and practical applications in forecasting, aviation, agriculture, and science.

Weathering: breakdown of rocks, soils and minerals Weathering Weathering is the in‑place breakdown of rocks, soils and minerals by physical, chemical and biological processes; it shapes landscapes, forms soil, and influences engineering and c…

Wells Gray–Clearwater Volcanic Field — Quaternary Basaltic Volcanism in British Columbia Wells Gray-Clearwater Volcanic Field Young Quaternary basaltic volcanic field in east‑central British Columbia featuring cinder cones, short shields, extensive lava flows and subglacial features around Wells Gray Prov…

Western Interior Seaway A vast inland sea that divided North America during much of the mid- and late Cretaceous, noted for its distinctive marine life, thick sedimentary deposits, and influence on contin…

Wind: Causes, Types, Effects, Measurement and Planetary Variations Wind Comprehensive overview of wind: what it is, how it forms, common classifications, impacts on environments and society, measurement methods, and notable planetary and solar examples…

Winter storm An overview of winter storms: how they form, typical characteristics, regional differences, impacts, forecasting and safety considerations.

World Ocean (Global Ocean) World Ocean The World Ocean denotes Earth’s continuous body of salt water, considered as one interconnected system comprising the named oceans and their margins, central to climate, biodiversi…

Xenolith (geology) Xenolith A xenolith is a fragment of rock trapped inside another rock, most commonly in igneous bodies; xenoliths and xenocrysts offer direct samples of deeper crust and mantle and inform g…

Year Without a Summer (1816): climatic and social impacts after Tambora Year without a Summer The Year Without a Summer (1816) followed the 1815 Mount Tambora eruption. Volcanic aerosols reduced sunlight, producing widespread cold, crop failures and social upheaval across E…

Yōmei Seamount Yōmei Seamount is an extinct underwater volcano in the Hawaiian–Emperor chain. Formed by hotspot volcanism in the Pacific, it last erupted about 60–65 million years ago and is name…

Yūryaku Seamount (guyot) Yūryaku Seamount Extinct, flat‑topped submarine volcano of the Hawaiian–Emperor chain in the Pacific Ocean. Formed over a mantle hotspot; last activity about 43 million years ago. Important to geol…

Zealandia: the mostly submerged continental fragment including New Zealand Zealandia Zealandia is a largely submerged continental fragment in the southwest Pacific. Mostly underwater, it includes New Zealand and New Caledonia and has a distinct geological history a…

Zircon — silicate mineral, gemstone, and source of zirconium Zircon Zircon (ZrSiO4) is a naturally occurring silicate mineral used as a gemstone and as the main ore of zirconium; it is important in geology for U–Pb dating and appears in many rock t…