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Cozamin
Cozamin is an underground copper-silver mine with a surface mill, 3.6 km from Zacatecas City, Mexico, producing continuously since 2006 under Capstone Copper, which agreed in 2026 to sell it to Luca Mining Corp.
Crater
A crater is a bowl-shaped or ringed depression on a solid planetary surface, formed either by a high-speed impact of an asteroid, meteoroid, or comet, or by volcanic collapse.
Craton
A craton is the ancient, stable core of a continent: crust mostly over 2.5 billion years old that has stayed tectonically quiet for hundreds of millions of years.
Creighton Mine
Creighton Mine is a deep underground nickel, copper, and platinum-group elements mine near Sudbury, Ontario, in production since 1901 and the deepest nickel mine in the world, hosting SNOLAB.
Cretaceous
The Cretaceous, the last period of the Mesozoic Era, lasted from 145 to 66 million years ago and saw flowering plants rise and dinosaurs rule the land.
Cretaceous–Paleogene boundary
The Cretaceous–Paleogene boundary, formerly the K–T boundary, marks the end of the Cretaceous Period 66 million years ago, when a mass extinction killed the non-avian dinosaurs.
Cretaceous–Paleogene extinction event
The Cretaceous–Paleogene (K–Pg, formerly K–T) extinction event was a mass extinction 66 million years ago that eliminated all non-avian dinosaurs, caused by the Chicxulub asteroid impact in Mexico.
Crevasse splay
A crevasse splay is a fan-shaped deposit of sand and mud on a floodplain, formed where floodwater escapes through a breached river levee and can eventually trigger an avulsion.
CrIS
CrIS (Cross-track Infrared Sounder) is a hyperspectral infrared spectrometer on NOAA's JPSS satellites, flying since 2012 on Suomi NPP, NOAA-20, and NOAA-21, measuring temperature and moisture profiles for weather forecasting.
Crisis of the Late Middle Ages
The Crisis of the Late Middle Ages was the cluster of famines, plague, war, revolt, and religious upheaval that struck Europe from 1315 to the mid-1400s.
Cristobalite
Cristobalite is a crystalline polymorph of silica, SiO2, thermodynamically stable only above 1470 °C but common metastably in volcanic domes, opal, and even lunar rock, and a regulated cause of silicosis.
Critical load
A critical load is the estimated deposition of a pollutant, most often acidifying sulfur and nitrogen compounds, below which significant harmful effects on a sensitive ecosystem do not occur.
Critical zone
The critical zone, often called Earth's living skin, is the near-surface layer where rock, soil, water, air, and organisms interact, supporting water supply and soil fertility.
Crust (geology)
The crust is the outermost layer of solid rock on the Earth, ranging from 5 to 70 km thick, divided into dense basaltic oceanic crust and lighter granitic continental crust.
Cryogenian
The Cryogenian period spans roughly 720 to 635 million years ago and is defined by the Sturtian and Marinoan glaciations, which reached equatorial latitudes and underpin the Snowball Earth hypothesis.
Cryovolcano
A cryovolcano is a volcano-like feature on an icy body that erupts water, nitrogen, methane, or ammonia instead of molten rock, as on Enceladus, Pluto, and Ceres.
Cryptomelane
Cryptomelane is a potassium manganese oxide mineral, the potassium-rich end-member of the hollandite group, with 2 × 2 tunnels hosting K⁺; it dates supergene weathering and serves as the catalyst K-OMS-2.
Crystal mush
Crystal mush is magma in which crystals form a connected, mostly solid framework with melt in the pore spaces, the dominant storage state of magma in the crust.
CTD (instrument)
A CTD (conductivity, temperature, depth) is the standard oceanographic instrument for profiling seawater, lowering conductivity, temperature, and pressure sensors from a research vessel to derive salinity and depth.
Cuesta
A cuesta is an asymmetric ridge formed by erosion of gently tilted rock layers, with a gentle dip slope on one side and a steep escarpment on the other.
Čukaru Peki mine
The Čukaru Peki mine, also known as Čukaru Peki, is an underground copper-gold mine near Bor in eastern Serbia, in production by Zijin Mining since 2021.
Cullinan Diamond
The Cullinan Diamond, a 3,106-carat stone, was the largest gem-quality rough diamond ever found, recovered at the Premier Mine near Pretoria, South Africa in 1905.
Cultural eutrophication
Cultural eutrophication is the human-caused acceleration of eutrophication, the over-enrichment of waters with nitrogen and phosphorus from sewage, fertilizers, and detergents, driving algal blooms and oxygen depletion.
Cultural significance of tornadoes
The cultural significance of tornadoes covers how societies explain the storm: Indigenous spirits like the Kiowa's Man-ka-ih, religious questions, The Wizard of Oz, and storm-chasing tourism.
Cumbre Vieja
Cumbre Vieja, Spanish for "old summit," is an active volcanic ridge on La Palma in the Canary Islands, home to all of the island's historical eruptions.
Cumbre Vieja tsunami hazard
The Cumbre Vieja tsunami hazard is the possibility that a large collapse of the Cumbre Vieja volcano's western flank on La Palma would generate an Atlantic-crossing tsunami.
Cummingtonite
Cummingtonite is a metamorphic rock-forming amphibole mineral, a magnesium iron silicate named in 1824 for Cummington, Massachusetts, that occurs chiefly in metamorphosed iron formations and forms a series with grunerite.
Cumulonimbus cloud
The cumulonimbus cloud (Cb) is a vertically developed convective cloud known as a thunderhead, one of the ten basic cloud genera, and the cloud that produces thunderstorms, lightning, and hail.
Cumulus cloud
Cumulus, from the Latin for heap, is a low-level cloud genus of dense, heaped, cauliflower-shaped clouds formed by convection; it usually signals fair weather but can grow into thunderstorm-producing cumulonimbus.
Curraghinalt
Curraghinalt is a gold, silver, and copper deposit in west Tyrone, Northern Ireland, where Dalradian Gold proposes an underground mine that could produce 3.5 million ounces of gold.