Niveo-aeolian or cryo-aeolian deposition is the process by which fine-grained

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

s are transported by wind and deposited on or mixed with snow or ice. The wind sweeps the snow and sand grains into

aeolian landform Aeolian landforms are features produced by either the erosive or constructive action of the wind. These features may be built up from sand or snow, or eroded into rock, snow, or ice. Aeolian landforms are commonly observed in sandy deserts and on ...

s such as

ripples Ripple may refer to: Science and technology * Capillary wave, commonly known as ripple, a wave traveling along the phase boundary of a fluid ** Ripple, more generally a disturbance, for example of spacetime in gravitational waves * Ripple (electri ...

, and further sorts the snow and ice grains into distinct layers. When snow melts or sublimates, the sediments are redeposited onto the surface below., forming patterns known as denivation features. Niveo-aeolian deposition is most widespread in polar climates, but may be found anywhere that is at least seasonally below freezing. In most places, much or all of the snow in these niveo-aeolian deposits melts in the spring or summer. However, "perennial" niveo-aeolian deposits have been observed in Antarctica's

Victoria Valley Victoria Valley is one of the larger McMurdo Dry Valleys in Antarctica. Lake Vida Lake Vida is a hypersaline lake in Victoria Valley, the northernmost of the large McMurdo Dry Valleys, on the continent of Antarctica. It is isolated under year-r ...

. Initially, after the wind has deposited it, the surface of a niveo-aeolian deposit typically consists of a rippled

bedform A bedform is a geological feature that develops at the interface of fluid and a moveable bed, the result of bed material being moved by fluid flow. Examples include ripples and dunes on the bed of a river. Bedforms are often preserved in the ro ...

of mixed sand and snow. Beneath the surface, the deposits commonly consist of alternating layers of snow and sediment. These layers may be up to thick. However, sometimes the sediment and snow are intermingled without distinct layers. Niveo-aeolian deposition plays an important role in soil transport in cold climates, such as the formation of

loess Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeolian ...

soils in Alaska through the deposition of windblown

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

. Further south, in coastal landscapes of the

Laurentian Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lake ...

, niveo-aeolian deposition facilitates the transport of sand into lakes and marshes, thus enhancing the sand signal. The prolonged denivation process also creates a source of fresh water, in the otherwise extremely dry dune and beach environment, for months after all surface snow has melted. Cryo-aeolian deposition has been proposed as one explanation for certain landforms on the planet Mars. In particular, denivation has been suggested as a cause of apparent meltwater fans in

Kaiser Crater ''Kaiser'' is the German word for "emperor" (female Kaiserin). In general, the German title in principle applies to rulers anywhere in the world above the rank of king (''König''). In English, the (untranslated) word ''Kaiser'' is mainly ap ...

. Proposed terrestrial analogs for these Martian landscapes include the Victoria Valley in Antarctica and the Great Kobuk Sand Dunes in Alaska.

Denivation

Sand covered shelf ice starts to crumble

During denivation, any outer snow melts first, so that the outer surface of the remaining niveo-aeolian deposit consists of sand. This surface sand exhibits tensional surface cracks due to the continued melting of the underlying snow. Denivation features may take several forms, including "snow ramparts" formed by

slumping Slumping is a technique in which items are made in a kiln by means of shaping glass over molds at high temperatures. The slumping of a pyrometric cone is often used to measure temperature in a kiln. Technique Slumping glass is a highly techni ...

down a dune or hill slope,

thermokarst Thermokarst is a type of terrain characterised by very irregular surfaces of marshy hollows and small hummocks formed as ice-rich permafrost thaws. The land surface type occurs in Arctic areas, and on a smaller scale in mountainous areas such as ...

ic sinkholes caused by melting below the surface,

hummock In geology, a hummock is a small knoll or mound above ground.Bates, Robert L. and Julia A. Jackson, ed. (1984). “hummock.” Dictionary of Geological Terms, 3rd Ed. New York: Anchor Books. p. 241. They are typically less than in height and ...

s caused by sediment draped over the remaining ice, spongy surfaces caused by the collapse of the sand and snow layers, and

debris flow Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally ...

s caused by meltwater. Smaller features include pellets, cracks, and dimples. Denivation features typically disrupt aeolian patterns only temporarily. After all the snow or ice has melted or sublimated, continued wind action gradually destroys them.

References

Works cited

* * * * * * *{{ Cite book , chapter-url = https://books.google.com/books?id=bLUHBAAAQBAJ&pg=PA117 , chapter = Short- and long-term perspectives on the evolution of a Lake Michigan foredune , pages = 195–216 , first = D. , last= van Dijk , isbn = 9780813725086 , title = Coastline and Dune Evolution along the Great Lakes , editor1-first = Timothy G. , editor1-last = Fisher , editor2-first = Edward C. , editor2-last = Hansen , publisher = Geological Society of America , year = 2014 Aeolian landforms Sedimentology Snow

Denivation

See also

References

Works cited