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Ice calving
Ice calving is the breakage of ice from glacier termini or ice shelves into icebergs, bergy bits, and growlers. It causes nearly all Antarctic and about half of Greenland's marine ice loss and dominates sea-level projection uncertainty.
Ice cauldron
Ice cauldron: circular or elongated depression in a glacier surface formed by enhanced basal melting from geothermal or volcanic heat, common on Iceland's Vatnajökull, Katla, and Grímsvötn glaciers, linked to jökulhlaups.
Ice sheet
An ice sheet is a mass of glacial land ice exceeding 50,000 km²; Earth's only two are the Greenland and Antarctic ice sheets, which hold most of Earth's fresh water.
Ice shelf
An ice shelf is a thick, floating platform of ice extending from a glacier or ice sheet over the ocean, found around Antarctica and parts of the Arctic.
Ice spike
Ice spike: an inverted-icicle-shaped ice formation growing upward from freezing water, formed when expanding ice extrudes water through a hole in the surface crust (Bally-Dorsey model). Favored near -7°C, with pure water and moving air; distinct from penitentes.
Ice stream
An ice stream is a band of fast-flowing ice within an ice sheet, moving far faster than the ice beside it and draining ice toward the ocean.
Iceberg
Iceberg: a mass of freshwater ice calved from a glacier or ice shelf floating in open water, at least 5 m above sea level. Also called tabular bergs (Antarctic) and growlers, bergy bits (smaller fragments); 13% above water, monitored by IIP and NIC.
Iceberg B-15
Iceberg B-15 was a tabular iceberg that calved from Antarctica's Ross Ice Shelf in March 2000, the largest reliably measured by satellite at about 11,000 square kilometers.
Icecap
Icecap (ice cap): a dome-shaped glacier mass under 50,000 km² flowing radially, distinct from ice sheets and ice fields; examples include Vatnajökull, Austfonna, and the Severny Island ice cap; Arctic ice caps lose 150–300 Gt of ice yearly.
Icecap depression
Icecap depression: gazetteer term (GeoNames code DPRG) for a comparatively depressed area on an icecap surface; classified under ice masses, distinct from isostatic bedrock depression beneath ice sheets.
Icecap dome
Icecap dome (ice dome): the dome-shaped central crest of an ice cap or ice sheet, from which ice flows outward in all directions; ice caps stay under 50,000 square kilometers, ice sheets only Greenland and Antarctica.
Icecap ridge
An icecap ridge is an elongated crest of ice on a dome-shaped ice cap, such as the Academy of Sciences Ice Cap. It is formed by central flows or glacial till.
Ichetuy Formation
Ichetuy Formation, a volcanogenic Jurassic (Oxfordian, about 164–157 Ma) siliciclastic unit in the Tugnuy Basin, Buryatia, Transbaikalia, Russia; bimodal rift volcanics and fossil insects, including beetles and sawflies, at Novospasskoye village.
Ik Kil
Cenote Ik Kil (place of the winds) is an open karst sinkhole cenote 3 km east of Chichen Itza in Pisté, Yucatán, Mexico: 60 m across, 26 m to the water, about 40 m deep, and among the region's most visited swimming cenotes.
Île Amsterdam
Île Amsterdam (Amsterdam Island, Nieuw Amsterdam) is a 58 km² French volcanic island in the southern Indian Ocean, part of the TAAF, home to the critically endangered Amsterdam albatross and the Martin-de-Viviès research base, hit by a major wildfire in 2025.
Île de la Cité
Île de la Cité: island in the Seine and historical heart of Paris, home of Notre-Dame, Sainte-Chapelle, and Conciergerie; fortified Roman castrum from 308, possibly the Gallic Parisii oppidum.
Île de la Gonâve
Île de la Gonâve (La Gonâve), a 750-km² limestone island off Haiti in the Gulf of Gonâve, its largest satellite island: severe water scarcity (7 L/person/day), deforestation, chronic food insecurity, and a 2025 gang blockade.
Île de Ré
Île de Ré: Atlantic island in Charente-Maritime, France, opposite La Rochelle, linked since 1988 by the 2,926.5 m toll Pont de l'Île de Ré; known for IGP salt, the 1627 battle of the pont du Feneau, and coastal-risk planning.
Île du Coin
Île du Coin (Coin Island) is the largest island of Peros Banhos atoll in the Chagos Archipelago, a former plantation port uninhabited from 1973 until 2026.
Île Kerguelen
Île Kerguelen (Grande Terre) is the main island of the Kerguelen Archipelago, a French subantarctic TAAF district at 49°S in the Indian Ocean; 6,675 km², Mount Ross 1,850 m, discovered 1772, scientific base Port-aux-Français.
Ile Pauline
Ile Pauline (Île Pauline) is a small uninhabited island in Pearse Strait, Bathurst Island complex, Queen Elizabeth Islands, Nunavut, Canada; 4 km², about 9 m high, within Qausuittuq National Park. Islands of the same name exist in South Australia and Quebec.
Ilha Caviana de Fora
Ilha Caviana de Fora (Ilha Caviana, Caviana Meridional), a low alluvial island in Pará, Brazil, in the Marajó archipelago at the Amazon mouth; former Aruã stronghold, split by a pororoca canal, now an APA with ribeirinho communities.
Ilha da Queimada Grande
Ilha da Queimada Grande (Snake Island, Ilha das Cobras), Brazilian Atlantic island off São Paulo, 35 km from Itanhaém coast, protected ARIE since 1985, home to 15,000+ endemic golden lanceheads (Bothrops insularis), uninhabited since 1918.
Ilha de Santiago
Ilha de Santiago (Santiago Island), largest island of Cape Verde at 991 km², home to Praia, the capital, and over half the national population; first settled in 1462, with UNESCO-listed Cidade Velha.
Ilha Grande de Gurupá
Ilha Grande de Gurupá (Curupa Island, Gurupa Island) is a 4,000 km² river island in the Amazon delta, Pará, Brazil, west of Marajó near the Amazon-Xingu confluence; second largest delta island, site of the 1623 Forte de Santo Antônio de Gurupá.
Ilha Janaucu
Ilha Janaucu (Janaucú, Ilha; also São Sebastião de Viçosa) is a 1-m-high island in Pará, Brazil, in the Amazon mouth. The Barra Norte entrance to the Port of Santana lies between it and Ilha de Curuá.
Ilha Mexiana
Ilha Mexiana (Mexiana Island), a 1,534 km² coastal island in Pará, Brazil, in the Marajó archipelago at the Amazon's mouth; the Equator crosses it; known for the 1901 Goeldi expedition and caiman hunting.
Iliamna (volcano)
Iliamna Volcano (VNUM 313020) is a 3,053-m glacier-covered andesitic stratovolcano in Lake Clark National Park, lower Cook Inlet, Alaska, 225 km southwest of Anchorage; no positively documented historical eruptions, frequent non-volcanic avalanches, alert level NORMAL/GREEN.
Iliniza
Iliniza (Los Ilinizas), twin-peaked potentially active stratovolcano in Ecuador's Western Cordillera about 50 km south of Quito; North edifice 123-116 ka, South edifice 46-25 ka with a VEI 5 Jatuncama eruption, Holocene Pongo lava flow 6±4 ka.
Imbabura (landform)
Imbabura (Taita Imbabura) is a potentially active compound stratovolcano in Ecuador, 60 km north of Quito, 4,609 m high, last confirmed eruption 5550 BCE, monitored by IG-EPN.