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Rincon (lithium project)
Rincon is a lithium-brine mining project on the Salar del Rincón in Salta province, Argentina, owned by Rio Tinto and its first commercial-scale lithium operation.
Ringwoodite
Ringwoodite is a high-pressure form of olivine, the most abundant mineral in Earth's mantle transition zone at about 525 to 660 km depth, first found in a meteorite.
Rio Grande Rift
The Rio Grande rift is a north-south continental rift where the crust has stretched in east-west extension, running from central Colorado through New Mexico into west Texas and northern Mexico.
Rip current
A rip current is a strong, narrow flow of water moving away from shore through the surf zone, and the leading cause of death at surf beaches.
Rip tide
A rip tide, also called a tidal rip, is a strong current formed by tidal water moving swiftly through an inlet or estuary mouth, distinct from a rip current.
River bed
River bed: the floor of a river channel, normally covered by water, made of alluvium or bedrock. Shaped by erosion, transport, and deposition; bankfull flows maintain it, and fine-sediment clogging degrades its habitat.
River continuum concept
The river continuum concept (RCC) is a 1980 theory in stream ecology holding that rivers show a continuous gradient of conditions from headwaters to mouth, producing predictable changes in communities.
River delta
River delta: landform of riverborne sediment deposited at the edge of an ocean or lake; classified by Galloway as river-, wave-, or tide-dominated; 40 large deltas studied show subsidence often exceeding sea-level rise.
Roaring Forties
The Roaring Forties are the latitudes between 40° and 50° south, where strong, steady westerly winds blow over the nearly landless Southern Ocean, powering eastbound sailing routes.
Robert FitzRoy
Robert FitzRoy was a British naval officer who commanded HMS Beagle on the voyage carrying Charles Darwin and founded the Met Office, issuing the first public weather forecasts.
Rock
A rock is a naturally occurring solid mass of one or more minerals, classified into igneous, sedimentary, and metamorphic types, which the rock cycle slowly transforms between over geologic time.
Rock (geology)
A rock is a naturally occurring solid aggregate of one or more minerals, or of matter like volcanic glass or coal, forming the Earth's crust.
Rock avalanche
A rock avalanche is a very rapid downslope flow of fragmented rock from a disintegrating rockfall or rockslide, often exceeding 100 km/h over a million cubic meters.
Rock cycle
The rock cycle is the geologic model describing how igneous, sedimentary, and metamorphic rocks are created, altered, and destroyed by processes at Earth's surface and interior.
Rock flour
Rock flour, also called glacial flour or glacier milk (French farine glaciaire), is fine silt-size sediment produced by glaciers grinding bedrock, which turns meltwater streams milky white.
Rock glacier
A rock glacier is a lobate or tongue-shaped landform of rock debris containing ice that creeps slowly downslope under permafrost, marked by a steep front and ridges.
Rock mechanics
Rock mechanics is the study of how intact rock and fractured rock masses respond to forces, applied to the design of tunnels, dam foundations, mines, and slopes.
Rock quality designation
Rock quality designation (RQD) is a geomechanics index expressing rock mass quality from drill core, counting only sound pieces 100 mm or longer, developed by Deere in 1963.
Rock-Eval pyrolysis
Rock-Eval pyrolysis is a standardized laboratory thermal-analysis method that heats small rock samples in stages to measure organic-carbon content, petroleum potential, kerogen type, and thermal maturity.
Rockfall
A rockfall is a type of landslide in which rocks detach from a steep slope or cliff and descend mainly by free-fall, bouncing, and rolling at very rapid speeds.
Rodinia
Rodinia is a hypothesized supercontinent that assembled between roughly 1,300 and 900 million years ago and broke apart between about 830 and 650 million years ago.
Rogue wave
A rogue wave, also called a freak wave, is an unusually large ocean surface wave, more than twice the height of the surrounding sea state.
Roman Warm Period
The Roman Warm Period, also called the Roman Climate Optimum, was a warm, wet, stable Mediterranean climate phase from about 200 BCE to 150 CE.
Rosebel Gold Mine
The Rosebel Gold Mine is a large open-pit gold mine in Brokopondo, Suriname, in commercial production since 2004 and owned by China's Zijin Mining since 2023.
Rosebery mine
The Rosebery mine is an underground polymetallic mine in Rosebery, on the west coast of Tasmania, Australia, wholly owned by MMG Limited and in continuous operation since 1936.
Rosette sampler
A rosette sampler is an oceanographic water-sampling device with 12 to 36 bottles around a CTD sensor package, lowered from a ship to profile the water column.
Roshydromet
Roshydromet (Росгидромет) is the Russian federal executive agency responsible for weather forecasting, hydrometeorology, and environmental pollution monitoring, operating under the Ministry of Natural Resources and Ecology.
Rossby wave
A Rossby wave, also called a planetary wave, is a large-scale westward-propagating oscillation in rotating fluids like Earth's ocean and atmosphere, predicted by meteorologist Carl-Gustaf Rossby in the 1930s.
Rossby waves
Rossby waves, also called planetary waves, are large-scale wave disturbances in Earth's atmosphere and ocean, identified by Carl-Gustaf Rossby in 1940, that shape the jet stream and drive persistent weather patterns.
Rotliegend
The Rotliegend is a stratigraphic unit of the Central European Permian, named from a miner's term for the red rock beneath the Mansfeld copper shale.