3,546 articles
Sierra Madre de Chiapas
Sierra Madre de Chiapas (Chiapas Sierra): 280-km Pacific-coast mountain range in southern Mexico averaging 2,000 m, part of the Maya block near the Cocos-Caribbean-North American triple junction, uplifted mainly in the Miocene, home to El Triunfo and La Sepultura biosphere reserves.
Sierra Madre del Sur (landform)
Sierra Madre del Sur, a mountain range in southern Mexico arcing from Michoacán to Oaxaca along the Pacific coast; about 1,100 km long, a Tertiary magmatic province, and a high-endemism biogeographic province and pine-oak ecoregion.
Sierra Madre Occidental
Sierra Madre Occidental, western Mexico's great silicic volcanic plateau and mountain range (also Sierra Tarahumara), runs over 2,000 km from the US border to the Trans-Mexican Volcanic Belt, formed by Farallon subduction and Gulf of California rifting.
Sierra Madre Oriental
Sierra Madre Oriental: major folded mountain range in eastern Mexico, one of Mexico's 14 biogeographic provinces, over 1,000 km long, a Jurassic-Cretaceous limestone fold-thrust belt deformed during the Laramide orogeny.
Sierra Nevada
Sierra Nevada: major mountain range of eastern California, about 640 km long, a granitic Mesozoic batholith with Mount Whitney (4,421 m); its snowpack supplies about one-third of California's water.
Sierra Nevada (Spain)
Sierra Nevada (Spain), the snowy range of Granada and Almería in Andalusia, is the Iberian Peninsula's highest mountain chain, with Mulhacén at 3,482 m, a 1999 national park, 1986 biosphere reserve, endemic-rich flora, and a major ski resort.
Siesta Key, Florida
Siesta Key, Florida: an 8-mile barrier island off Sarasota on the Gulf coast, famed for 99% quartz sand that stays cool, Siesta Beach's 950-space free lot, lifeguards, and top rankings including No. 28 on the 2026 World's 50 Best Beaches list.
Sikaram Sar
Sikaram Sar (سیکرم, Mount Sikaram), 4,755 m, is the highest peak of the Spīn Ghar (Safēd Kōh) range on the Afghanistan–Pakistan border south of the Khyber Pass, an ultra-prominent summit (2,295 m) and type locality of the Sikaram Series.
Sikhote-Alin
Sikhote-Alin (Сихотэ-Алинь) is a mountain range running about 1,200 km along the Sea of Japan through Primorsky and Khabarovsk Krais in the Russian Far East.
Sillem Island
Sillem Island, officially Qikiqtaaluk (ᕿᑭᖅᑖᓗᒃ), is an uninhabited glaciated island in Baffin Bay off northern Baffin Island, Nunavut, Canada; 482 km², separating Gibbs and Clark Fiords, within proposed Agguttinni Territorial Park.
Silverthrone
Silverthrone (Mount Silverthrone) is a remote 20-km-wide caldera complex and stratovolcano in the Coast Mountains of southwestern British Columbia, Canada, mainly erupted 100,000-500,000 years ago, with no known Holocene eruptions and a Moderate Canadian threat ranking.
Silvertip Mtn.
Silvertip Mountain, a 2,596 m ultra-prominence peak in the Skagit Range of the Canadian Cascades south of Hope, BC; most prominent non-volcanic Cascade peak, first climbed 1908.
Simandou
Simandou is a 110-kilometer mountain range in Guinea holding one of the world's largest untapped high-grade iron ore deposits, with the first shipment in December 2025.
Simeulue
Simeulue is an Indonesian island about 150 kilometers off the west coast of Sumatra and the seat of a regency in Aceh province, centered on Sinabang.
Simplon Pass
Simplon Pass (Simplonpass, passo del Sempione, col du Simplon): 2,005 m Swiss Alpine pass in Valais linking Brig with Domodossola, Italy; Stockalper trade route, Napoleon's 1801–1805 road, and the 19.8 km Simplon rail tunnel of 1906.
Simpson Desert
Simpson Desert (Munga-Thirri): large Australian sand-ridge desert in SA, QLD, and NT, about 176,500 km², with parallel longitudinal dunes 10–40 m high, under 150 mm annual rain, named by Cecil Madigan in the 1930s.
Sinai Peninsula
Sinai Peninsula: triangular Egyptian landmass of about 61,000 km² between the Mediterranean, Gulf of Suez, and Gulf of Aqaba; highest peak Mount Catherine (2,637 m); returned to Egyptian sovereignty in 1982 under the 1979 peace treaty.
Sindalah (سندالة)
Sindalah (سندالة) is a luxury island resort in the Red Sea, about five kilometers off the NEOM coastline in northwest Saudi Arabia, and the first NEOM destination to open.
Singapore Island
Singapore Island (Pulau Ujong) is the main island of the Republic of Singapore, about 49 by 28 km with a 224 km coastline, generally flat within 15 m of sea level, and grown roughly 25 percent by land reclamation since 1822.
Singkep Island
Singkep Island (Pulau Singkep) is a 757-square-kilometer island in Indonesia's Lingga Archipelago, Riau Islands Province, separated from Sumatra by the Berhala Strait and known for its tin mining era.
Sinkhole
Sinkhole (doline): closed ground depression with no external surface drainage, formed by collapse or subsidence into voids dissolved in karst rocks like limestone, gypsum, or salt; types include dissolution, cover-subsidence, and cover-collapse, plus human-induced forms from pumping, construction, and mining.
Sinkhole formation mechanisms and types
Sinkholes form when weak carbonic acid dissolves limestone or soil collapses into cavities; types include dissolution, suffosion, and cover-collapse sinkholes, many triggered by groundwater pumping.
Sinkhole hazard assessment and mitigation
Sinkhole hazard assessment and mitigation is the set of methods for mapping sinkhole susceptibility, confirming site risk, stabilizing ground, and spreading costs through insurance and land-use rules.
Sinkholes as tourist attractions
Sinkhole tourism develops collapsed karst landforms, from sheer-walled Chinese tiankeng to water-filled Yucatán cenotes, as managed visitor sites: lookout parks, extreme-sports venues, swimming holes, and dive locations.
Sinkholes in popular culture
Sinkholes in popular culture examines sinkholes as media spectacle, from the televised 1981 Winter Park, Florida collapse and the 2013 Seffner fatality to documentaries and NBC's La Brea.
Sinsk Formation
Sinsk Formation: Early Cambrian lime mudstone unit (516–513 Ma, Botomian) on the Siberian Platform, Sakha, Russia, with exceptionally preserved fossils and the type record of the Sinsk event, the first major Phanerozoic extinction.
Sint Eustatius
Sint Eustatius, known locally as Statia, is a small Dutch Caribbean island in the Leeward Islands that became a special municipality of the Netherlands in 2010.
Siple Island
Siple Island, a snow-covered Antarctic island about 70 mi long in Marie Byrd Land along the Getz Ice Shelf, hosts Mount Siple, a 3,110 m shield volcano, and is named for explorer Paul Siple.
Sipura Island
Sipura (Sipora) Island, Mentawai Islands Regency, West Sumatra, Indonesia: smallest of the four main Mentawai islands, site of Tuapejat regency capital, surf breaks like Lance's Right, and high northern tsunami vulnerability.
Siquijor
Siquijor, also called Isla del Fuego (Island of Fire), is the third smallest island province of the Philippines, in Central Visayas; 343.50 km2, six municipalities, provincial since 1971, known for folk healers and growing tourism.