Fast ice (also called ''land-fast ice'', ''landfast ice'', and ''shore-fast ice'') is

sea ice Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's o ...

that is "fastened" to the coastline, to the

sea floor The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

along

shoal In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It ...

s or to grounded icebergs.Leppäranta, M. 2011. The Drift of Sea Ice. Berlin: Springer-Verlag. Fast ice may either grow in place from the

sea water Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approx ...

or by freezing pieces of drifting ice to the shore or other anchor sites.Kovacs, A.and M. Mellor. 1974. "Sea ice morphology and ice as a geologic agent in the Southern Beaufort Sea." pp. 113-164, in: ''The Coast and Shelf of the Beaufort Sea'', J.C. Reed and J.E. Sater (Eds.), Arlington, Va.: U.S.A. Unlike drift (or pack) ice, fast ice does not move with currents and winds. The width (and the presence) of this ice zone is usually seasonal and depends on ice thickness, topography of the sea floor and islands. It ranges from a few meters to several hundred kilometers. Seaward expansion is a function of a number of factors, notably water depth, shoreline protection, time of year and pressure from the pack ice. In Arctic seas the fast ice extends down to depths of , while in the

Subarctic The subarctic zone is a region in the Northern Hemisphere immediately south of the true Arctic, north of humid continental regions and covering much of Alaska, Canada, Iceland, the north of Scandinavia, Siberia, and the Cairngorms. Genera ...

seas, the zone extends to depths of about . In some coastal areas with abrupt shelf and no islands, e.g., in the

Sea of Okhotsk The Sea of Okhotsk ( rus, Охо́тское мо́ре, Ohótskoye móre ; ja, オホーツク海, Ohōtsuku-kai) is a marginal sea of the western Pacific Ocean. It is located between Russia's Kamchatka Peninsula on the east, the Kuril Islands ...

off

Hokkaidō is Japan, Japan's Japanese archipelago, second largest island and comprises the largest and northernmost Prefectures of Japan, prefecture, making up its own List of regions of Japan, region. The Tsugaru Strait separates Hokkaidō from Honshu; th ...

, tides prevent the formation of any fast ice. Smaller ocean basins may contain only the fast ice zone with no

pack ice Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.).Leppäranta, M. 2011. The Drift of Sea Ice. Berlin: Springer-Verlag. Unlike fast ice, which is "faste ...

(e.g.

McMurdo Sound McMurdo Sound is a sound in Antarctica. It is the southernmost navigable body of water in the world, and is about from the South Pole. Captain James Clark Ross discovered the sound in February 1841, and named it after Lt. Archibald McMurdo ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

). The topography of the fast ice varies from smooth and level to rugged (when submitted to large pressures). The ''ice foot'' refers to ice that has formed at the shoreline, through multiple freezing of water between ebb tides, and is separated from the remainder of the fast ice surface by ''tidal cracks''.{{cite book , first=P. , last=Wadhams , title=Ice in the Ocean , year=2000 , publisher=CRC Press , isbn=978-90-5699-296-5 Further away from the coastline, the ice may become anchored to the sea bottom—it is then referred to as ''bottomfast ice''. Fast ice can survive one or more melting seasons (''i.e.'' summer), in which case it can be designated following the usual age-based categories: first-year, second-year, multiyear. The ''fast ice boundary'' is the limit between fast ice and drift (or pack) ice—in places, this boundary may coincide with a shear ridge. Fast ice may be delimited or enclose pressure ridges which extend sufficiently downward so as to be grounded—these features are known as stamukhi.

References

Sea ice Glaciology Bodies of ice

See also

References