- Duricrust
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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 and (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, commonly assisted in arid settings by evaporation.[1][2][3] Minerals often found in duricrust include silica, iron, calcium, and gypsum.
Duricrusts need to be formed in absolute accumulation, therefore they must have a source, transfer and precipitation. Duricrust is often studied during missions to Mars because it may help prove 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.[4] Phoenix's duricrust was later confirmed to be water-based.[5]
References
- ^ Dixon, 1994
- ^ Woolnough, 1930
- ^ NADMSC SLTT, 2004
- ^ Rayl, A.J.S. (June 1, 2008). "Holy Cow, Snow Queen! Phoenix Landed on Ice, Team Thinks". The Planetary Society. http://www.planetary.org/news/2008/0601_Holy_Cow_Snow_Queen_Phoenix_Landed_on.html. Retrieved November 12, 2008.
- ^ "Phoenix and the Holy Cow". Astronomy Picture of the Day. November 12, 2008. http://apod.nasa.gov/apod/ap081112.html. Retrieved November 12, 2008.
External links
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