{{Short description|Type of surface soil layer}} {{Infobox soil | name = Duricrust | alternative_name = | image = De Yalgo a Dori Marco Schmidt 0922.jpg | image_caption = A duricrust inselberg near Dori, Burkina Faso | image_size = | type = | classification_system = | code = | profile = | mineral = Soluble minerals | process = | parent_material = | climate = Arid | ph = | horizons = | composition = Various | composition_secondary = Various }}
'''Duricrust''' is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters.
It is a general term (not to be confused with duripan) for a zone of chemical precipitation and hardening formed at or near the surface of sedimentary bodies through pedogenic or non-pedogenic processes. It is typically formed by the accumulation of soluble minerals deposited by mineral-bearing waters that move upward, downward, or laterally by capillary action. It is commonly assisted in arid settings by evaporation.<ref name="DixonOthers2009a">Dixon, J.C. and McLaren, S.J., 2009. ''Duricrusts''. In A.J. Parsons and A.D. Abrahams, ed., pp. 123-151. ''Geomorphology of desert environments.'' Springer, Dordrecht. {{ISBN|978-1-4020-5718-2}}</ref><ref name="Woolnough1930a">Woolnough, W.G., 1930. ''The influence of climate and topography in the formation and distribution of products of weathering.'' ''Geological Magazine'', 67(3), pp.123-132.</ref> There are different types of duricrusts, each distinguished by a dominant mineralogy. For example, ferricrete (laterite) is dominated by sesquioxides of iron; alcrete (bauxite) is dominated by sesquioxides of aluminum; silcrete by silica; calcrete (caliche) by calcium carbonate, and gypcrete (gypcrust) by gypsum.<ref name="DixonOthers2009a"/>
Duricrust is often studied during missions to Mars because it may help prove that the planet once had more water. Duricrust was found on Mars at the Viking 2 landing site, and a similar structure, nicknamed "Snow Queen", was found under the Phoenix landing site.<ref>{{cite web |title=Holy Cow, Snow Queen! Phoenix Landed on Ice, Team Thinks |last=Rayl |first=A.J.S. |work=The Planetary Society |date=June 1, 2008 |url=http://www.planetary.org/news/2008/0601_Holy_Cow_Snow_Queen_Phoenix_Landed_on.html |accessdate=November 12, 2008 |url-status=dead |archiveurl=https://web.archive.org/web/20080605010056/http://www.planetary.org/news/2008/0601_Holy_Cow_Snow_Queen_Phoenix_Landed_on.html |archivedate=June 5, 2008 }}</ref> Phoenix's duricrust was later confirmed to be water-based.<ref>{{Cite APOD | title = Phoenix and the Holy Cow | date = November 12, 2008 | access-date = November 12, 2008 }}</ref>
==References== {{reflist}}
==Further reading== * DILL, H.G., WEBER, B. and BOTZ, R. (2013) Metalliferous duricrusts (“orecretes”) - markers of weathering: A mineralogical and climatic-geomorphological approach to supergene Pb-Zn-Cu-Sb-P mineralization on different parent materials.- Neues Jahrbuch für Mineralogie Abhandlungen, 190: 123-195
==External links== *[https://archive.today/20121212020912/http://www.tec.army.mil/research/products/desert_guide/lsmsheet/lsduri.htm Description] *[http://www.nasa.gov/vision/earth/technologies/31jan_sandsofmars.html NASA: The Sands of Mars]
Category:Soil Category:Sedimentary rocks
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