Earth science

Mount Buninyong — extinct scoria cone near Ballarat, Victoria Mount Buninyong Mount Buninyong is a prominent extinct scoria cone about 15 km southeast of Ballarat, Victoria. It rises to about 745 m, has a breached crater, native forest, walking trails and cu…

Mount Cayley: eroded stratovolcano in British Columbia's Garibaldi Belt Mount Cayley Mount Cayley is an eroded stratovolcano in southwestern British Columbia, part of the Garibaldi Volcanic Belt and the Cascade Arc. It is monitored for seismic and glacial hazards a…

Mount Cayley volcanic field (British Columbia) Mount Cayley volcanic field A volcanic field on the south coast of British Columbia centered on Mount Cayley, notable for subglacial eruptions that produced tuyas, lava domes and a complex record of Quaternar…

Mount Cheaha — Highest Point in Alabama Mount Cheaha Mount Cheaha (Cheaha Mountain) is Alabama's highest point at 2,407 ft (734 m). Part of the Talladega Range and in Cheaha State Park, it features quartzite outcrops, trails, overloo…

Mount Chimborazo Mount Chimborazo is Ecuador's highest peak and an extinct volcano whose summit is the point on Earth's surface farthest from the planet's center, a result of its location near the…

Mount Edziza volcanic complex, British Columbia Mount Edziza Mount Edziza is a large, mostly basaltic volcano and volcanic plateau in northwestern British Columbia, Canada, notable for its cinder cones, lava fields and protected provincial p…

Mount Erebus (Antarctica) Mount Erebus Active Antarctic volcano on Ross Island, known for its persistent lava lake, unique geology, scientific study, and status as the southernmost active volcano.

Mount Etna: Sicily’s active stratovolcano and its impact Mount Etna Mount Etna is Europe's largest active volcano on Sicily's east coast, famed for frequent eruptions, fertile soils, scientific study, tourism and long-term monitoring.

Mount Garibaldi — a dacitic stratovolcano in southwestern British Columbia Mount Garibaldi Mount Garibaldi is an eroded dacitic stratovolcano in southwestern British Columbia, part of the Cascade arc; its Pleistocene history, glacier interactions and potential hazards af…

Mount Meager Mount Meager is a potentially active volcanic complex in southwestern British Columbia, notable for silicic lava, glaciation, landslide hazards and its place in the Garibaldi Volca…

Mount Pinatubo: 1991 eruption, features, impacts and recovery Mount Pinatubo Mount Pinatubo is a stratovolcano on Luzon, Philippines, whose 1991 eruption created a caldera, produced widespread ash and lahars, caused hundreds of deaths, and had notable local…

Mount Rainier: geology, history, ecology, and recreation Mount Rainier Mount Rainier is a glaciated stratovolcano southeast of Seattle and the highest peak in the Cascade Range; important for geology, ecology, cultural history, climbing, and volcanic…

Mount Redoubt (Alaska volcano) Mount Redoubt Mount Redoubt is an active stratovolcano in Alaska's Chigmit Mountains, about 100 miles southwest of Anchorage. It has produced ash clouds and lahars that have affected aviation an…

Mount Rinjani (Gunung Rinjani), Lombok, Indonesia Mount Rinjani Active volcano on Lombok rising to 3,726 m. Noted for its large caldera and Segara Anak crater lake, cultural importance, rich biodiversity and popular but challenging trekking. La…

Mount Rowan: extinct volcano near Ballarat, Victoria Mount Rowan Mount Rowan is a small extinct volcano on the outskirts of Ballarat, Victoria. Its lava flows date to the Pliocene and it forms part of the Western Victorian Volcanic Plains and lo…

Mount Ruapehu Active stratovolcano in New Zealand’s central North Island, highest peak on the island and a focal point for recreation, Māori culture, and volcanic hazards.

Mount Shasta: geology, glaciers, history, and human significance Mount Shasta Mount Shasta is a prominent Cascade stratovolcano in northern California, noted for its height, glaciers, eruptive history, cultural importance, and recreational opportunities.

Mount Silverthrone: Silverthrone Caldera in the Ha-Iltzuk Icefield (British Columbia) Mount Silverthrone Mount Silverthrone is a 20 km-wide, deeply dissected caldera complex in southwestern British Columbia. Formed by Pleistocene volcanism, it is heavily glaciated and is the highest p…

Mount Tambora: Indonesian stratovolcano and the great 1815 eruption Mount Tambora Mount Tambora is an active Indonesian stratovolcano known for its massive 1815 eruption, which formed a large caldera and caused worldwide climatic effects and regional devastation…

Mount Unzen (Unzen-dake) — active volcanic complex on Kyūshū, Japan Mount Unzen Active volcanic complex on the Shimabara Peninsula, Kyūshū, Japan, notable for lava domes, hot springs, historic deadly eruptions (including 1792 and 1990s activity), and extensive…

Mount Vesuvius: geology, history, hazards and cultural legacy Mount Vesuvius An overview of Mount Vesuvius — its geology, famous eruptions (including AD 79), archaeological legacy, risk to surrounding communities, and scientific monitoring.

Mud volcano Mud volcanoes are cold geological vents that release mixtures of water, fine sediment and gases—mainly methane—creating domes or pools on land and the seafloor; they differ from ma…

Mudflow: causes, behavior, hazards and volcanic lahars Mudflow Mudflows are rapid, water‑rich landslides that move soil, rock and debris downhill. This article explains their mechanics, causes (including lahars), risks, and common mitigation m…

Mudrock: fine-grained siliciclastic sedimentary rocks and their importance Mudrock Mudrocks are the most abundant fine-grained sedimentary rocks. This article explains their composition, types, classification challenges, history, uses, and significance for fossil…

Mudstone: a fine-grained siliciclastic sedimentary rock Mudstone Mudstone is a fine-grained siliciclastic rock made of mixed silt- and clay-sized particles. It forms in low-energy settings, preserves delicate fossils and is distinct from shale b…

Murchison meteorite — 1969 fall in Victoria, Australia Murchison meteorite A well-studied carbonaceous chondrite that fell in 1969 near Murchison, Victoria. Noted for abundant water-altered minerals and a rich inventory of organic compounds with implicati…

National Hurricane Center: role, functions, and public guidance National Hurricane Center U.S. National Hurricane Center (NHC): responsibilities, forecasting products, data sources, coordination with WMO, and how watches, warnings and track forecasts are issued.

Nazca Plate: Oceanic tectonic plate off western South America Nazca plate The Nazca Plate is an oceanic tectonic plate in the eastern Pacific whose eastward subduction beneath South America drives the Andes, large earthquakes, volcanism and coastal trenc…

Nazko Cone — cinder cone of the Anahim Volcanic Belt, British Columbia Nazko Cone Nazko Cone is a small basaltic cinder cone in central British Columbia, part of the Anahim Volcanic Belt. Its last eruption occurred about 7,200 years ago; a 2007 earthquake swarm…

Neoarchaean Era: final stage of the Archaean (2.8–2.5 billion years ago) Neoarchaean The Neoarchaean (Neoarchean) is the last era of the Archaean eon (c. 2.8–2.5 Ga). It saw major crustal growth, the rise of oxygen-producing microbes and formation of early supercon…

Neogene: geology, climate, life and significance Neogene The Neogene is a geologic period within the Cenozoic characterized by cooling climates, expansion of grasslands, evolution of modern mammals and birds, and the appearance of early…

Neoproterozoic Era: breakup of Rodinia, Snowball Earth, and early multicellular life Neoproterozoic The Neoproterozoic (1,000–541 million years ago) includes the Tonian, Cryogenian and Ediacaran periods, marked by continental reorganization, extreme glaciations and the first wide…

Nevado del Ruiz — snow‑capped volcano in Colombia and the Armero disaster Nevado del Ruiz Nevado del Ruiz is an active, glacier‑topped volcano in Colombia famous for its deadly 1985 lahar that destroyed Armero; it remains an important study case for volcanic hazards and…

Nevado Tres Cruces High Andean volcanic massif on the Argentina–Chile border, notable for its multiple summits including Tres Cruces Sur (6,748 m) and its history of mountaineering and scientific int…

New Red Sandstone Red, desert-derived sandstones deposited from the late Permian into the early Triassic (late Paleozoic–early Mesozoic). Common in Britain, notable for iron-rich red colour, desert…

Nintoku Seamount Nintoku Seamount is an extinct flat-topped submarine volcano (guyot) in the Hawaiian–Emperor chain of the Pacific Ocean, formed by hotspot volcanism and later eroded and subsided b…

Nitrogen narcosis A reversible impairment of mental and motor function experienced by divers at increased depth due to elevated nitrogen partial pressure; symptoms resemble alcohol intoxication and…

Nor'easter (Northeaster): Coastal Storms of the U.S. East Coast Nor'easter Nor'easters are extratropical cyclones that form off North America's East Coast, bringing strong northeast winds, heavy precipitation, coastal flooding, and erosion—most often in l…

North American Plate A comprehensive overview of the North American tectonic plate: extent, boundaries, internal structure, geological history, and its significance to earthquakes and landscape evoluti…

Nubian Sandstone Aquifer System A vast transboundary groundwater reservoir beneath the eastern Sahara, often described as the world’s largest fossil-water aquifer; vital for drinking, irrigation and regional plan…

Nuclear winter: causes, effects, history, and uncertainties Nuclear winter Nuclear winter is a hypothesized global climate disruption caused by soot and smoke from large-scale nuclear war, with potential cooling, agricultural collapse, and long-term envir…

Numerical weather prediction Numerical weather prediction (NWP) uses mathematical models, observations and computing to forecast the atmosphere. Covers principles, models, data assimilation, ensembles, limitat…

Nuvvuagittuq Greenstone Belt A very old, metamorphosed sequence of volcanic and sedimentary rocks on the eastern shore of Hudson Bay, Canada; key to studies of early Earth's crust and debated evidence of ancie…

Nyamuragira: Shield Volcano and One of Africa's Most Active Volcanoes Nyamuragira Nyamuragira, a 3,058 m shield volcano in eastern DRC, is among Africa’s most active—frequently producing effusive basaltic eruptions and widespread lava flows that reshape surround…

Oblate spheroid: geometry, causes, and examples Oblate spheroid An oblate spheroid is an axisymmetric ellipsoid flattened at the poles by rotation. This article describes its shape, parameters, physical origin, examples (Earth, planets, stars),…

Obsidian Obsidian is a natural volcanic glass formed by rapid cooling of silica-rich lava. It is a mineraloid valued for its glassy fracture, historical tools, decorative uses and occasiona…

Occluded front An occluded front is a composite weather front formed when a faster cold front overtakes a slower warm front, producing characteristic cloud bands, precipitation, and changes in te…

Ocean A comprehensive overview of Earth's oceans: their extent, structure, major divisions, ecosystems, role in climate, human uses, and contemporary threats.