Sastrugi, or zastrugi, are features formed by the

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

of snow by wind. They are found in polar regions, and in snowy, wind-swept areas of temperate regions, such as frozen lakes or mountain ridges. Sastrugi are distinguished by upwind-facing points, resembling

anvil An anvil is a metalworking tool consisting of a large block of metal (usually Forging, forged or Steel casting, cast steel), with a flattened top surface, upon which another object is struck (or "worked"). Anvils are massive because the hi ...

s, which move downwind as the surface erodes. These points usually lie along ridges parallel to the prevailing wind; they are steep on the

windward In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point ...

side and sloping to the

leeward In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point o ...

side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges. Large sastrugi are troublesome to skiers and

snowboard Snowboards are boards where the user places both feet, usually secured, to the same board. The board itself is wider than most skis, with the ability to glide on snow."snowboarding." Dictionary.com Unabridged (v 1.1). Random House, Inc. 17 Mar ...

ers. Traveling on the irregular surface of sastrugi can be very tiring and can risk breaking equipment; ripples and waves are often undercut, and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough.

Etymology

The words ''sastrugi'' and ''zastrugi'' are Russian-language

plural In many languages, a plural (sometimes list of glossing abbreviations, abbreviated as pl., pl, , or ), is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity greater than ...

s; the

singular Singular may refer to: * Singular, the grammatical number that denotes a unit quantity, as opposed to the plural and other forms * Singular or sounder, a group of boar, see List of animal names * Singular (band), a Thai jazz pop duo *'' Singula ...

is ''zastruga''. The form ''sastruga'' started as the German-language transliteration of the Russian word заструга (plural: заструги).C. Fitzhugh Talman:
The singular of “sastrugi”
', Monthly Weather Review 43, February 1915, p. 85–86 A

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

-type analogical singular ''sastrugus'' is used in various writings on exploration of the South Pole, including

Robert Falcon Scott Captain Robert Falcon Scott (6 June 1868 – ) was a British Royal Navy officer and explorer who led two expeditions to the Antarctic regions: the Discovery Expedition, ''Discovery'' expedition of 1901–04 and the Terra Nova Expedition ...

's expedition's diaries and

Ernest Shackleton Sir Ernest Henry Shackleton (15 February 1874 – 5 January 1922) was an Anglo-Irish Antarctic explorer who led three British expeditions to the Antarctic. He was one of the principal figures of the period known as the Heroic Age of Antarcti ...

's '' The Heart of the Antarctic''.

Formation mechanism

Under the action of steady wind, free snow particles accumulate and drift like the sand grains in barchan

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

s, and the resulting drifting snow shapes are also popularly referred to as ''barchans''.

Inuit Inuit (singular: Inuk) are a group of culturally and historically similar Indigenous peoples traditionally inhabiting the Arctic and Subarctic regions of North America and Russia, including Greenland, Labrador, Quebec, Nunavut, the Northwe ...

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

call them ''kalutoqaniq''. When winds slacken, the drifted formations consolidate via sublimation and recrystallization. Subsequent winds erode kalutoqaniq into the sculptured forms of sastrugi. Inuit call large sculpturings ''kaioqlaq'' and small ripples ''tumarinyiq''. Further erosion may turn ''kaioqlaq'' back into drifting ''kalutoqaniq''. An intermediate stage of erosion is ''mapsuk'', an overhanging shape. On the windward side of a ridge, the base erodes faster than the top, producing a shape like an anvil tip pointing upwind.Wonders, William C., ''Canada's changing North,'' Mcgill Queens Univ Press, 2003
p. 40
/ref>

On sea ice

Sastrugi are more likely to form on first-year sea ice than on multiyear ice. First-year ice is smoother than multiyear ice, which allows the wind to pass uniformly over the surface without topographic obstructions. Except during the melt season, snow is dry and light in climates cold enough for sea ice, allowing the snow to be easily blown and create sastrugi parallel to the wind direction. The locations of sastrugi are fixed by March in the northern hemisphere and may be linked to the formation of melt ponds. Melt ponds are more likely to form in the depressions between sastrugi on first-year ice.

References

* * {{cite book , last= Shackleton , first= Sir Ernest Henry , date= 1909 , title= The Heart of the Antarctic: Being the Story of the British Antarctic Expedition, 1907-1909 , publisher= Basic Books , isbn= 978-0-7867-0684-6 , url-access= registration , url= https://archive.org/details/heartofantarctic0000shac Snow or ice weather phenomena Aeolian landforms Geography of the Arctic Geography of Antarctica

Etymology

Formation mechanism

On sea ice

See also

References