Yardangs on Mars

{{Short description|Aeolian formation}}

File:Zooming on the yardangs of Mount Sharp with Remote Micro Imager - sol 1994.jpg with Remote Micro Imager on the Curiosity rover - sol 1994|350px]]

Yardangs are common in some regions on Mars, especially in the Medusae Fossae Formation. This formation is found in the Amazonis quadrangle and near the equator.[http://adsabs.harvard.edu/abs/1979JGR....84.8147W SAO/NASA ADS Astronomy Abstract Service: Yardangs on Mars], Journal of Geophysical Research Vol. 84, Issue B14, 30 December 1979. https://doi.org/10.1029/JB084iB14p08147 They are formed by the action of wind on sand sized particles; hence they often point in the prevailing direction that the winds were blowing when they were formed.[http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Yardangs_on_Mars Yardangs on Mars], ESA Mars Express, 23 Jul 2004 [http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2004/07/yardangs_on_the_surface_of_mars/10312091-3-eng-GB/Yardangs_on_the_surface_of_Mars.jpg ESA High-resolution image, Yardangs on Mars near Olympus Mons on Mars], image taken by the High Resolution Stereo Camera (HRSC) on board the ESA Mars Express spacecraft. Yardangs exhibit very few impact craters, indicating that the surface exposed is relatively young and the process of erosion may be active.[http://themis.asu.edu/zoom-20020416a THEMIS image of Medusae Fossae Formation], ASU, 2002-04-16 The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Yardangs are parts of rock that have been sand blasted into long, skinny ridges by bouncing sand particles blowing in the wind.[http://www.uahirise.org/ESP_039563_1730 Yardangs in Arsinoes Chaos] University of Arizona HiRISE Operations, 04 January 2015{{Cite web|url=http://www.uahirise.org/ESP_039563_1730|title=HiRISE | Yardangs in Arsinoes Chaos (ESP_039563_1730)}} Layers are seen in parts of the formation. A resistant caprock on the top of yardangs has been observed in Viking,{{cite journal | last1= Scott | first1= David H. | last2= Tanaka | first2= Kenneth L. | title= Ignimbrites of Amazonis Planitia Region of Mars | journal= Journal of Geophysical Research | volume= 87 | pages= 1179–1190 | bibcode = 1982JGR....87.1179S | date= 1982 | doi = 10.1029/JB087iB02p01179 }} Mars Global Surveyor,{{cite journal |last1=Malin |first1=MC |last2=Carr |first2=MH |last3=Danielson |first3=GE |last4=Davies |first4=ME |last5=Hartmann |first5=WK |last6=Ingersoll |first6=AP |last7=James |first7=PB |last8=Masursky |first8=H |last9=McEwen |first9=AS |last10=Soderblom |first10=L. A. |last11=Thomas |first11=P |last12=Veverka |first12=J |last13=Caplinger |first13=M. A. |last14=Ravine |first14=M. A. |last15=Soulanille |first15=T. A. |last16=Warren |first16=J. L. |title=Early views of the martian surface from the Mars Orbiter Camera of Mars Global Surveyor |journal=Science |volume=279 |issue=5357 |pages=1681–5 |date=March 1998 |pmid=9497280 |doi= 10.1126/science.279.5357.1681|bibcode = 1998Sci...279.1681M |display-authors=8 |doi-access=free }} and HiRISE photos.{{cite journal | last1= Mandt | first1= Kathleen E. | last2= De Silva | first2= Shanaka L. | last3= Zimbelman | first3= James R. | last4= Crown | first4= David A. | title= The origin of the Medusae Fossae Formation, Mars: Insights from a synoptic approach| doi = 10.1029/2008JE003076 | date= 2008 | volume= 113 | pages= 12011 | journal= Journal of Geophysical Research | hdl=10088/7052 | bibcode=2008JGRE..11312011M| doi-access= free }} Images from spacecraft show that they have different degrees of hardness probably because of significant variations in the physical properties, composition, particle size, and/or cementation.

File:Medusae Fossae Formation.jpg|Medusae Fossae Formation as seen with Mars Odyssey's THEMIS. Notice elongated formations called yardangs.

WikiESP 035295 1885yardangstop.jpg|Yardangs of various sizes, as seen by HiRISE under HiWish program.

WikiESP 039563 1730yardangs.jpg|Yardangs formed in light-toned material and surrounded by dark, volcanic basalt sand, as seen by HiRISE under HiWish program.

WikiESP 039563 1730yardangsclose.jpg|Close-up image of yardangs, as seen by HiRISE under HiWish program. Arrows point to transverse aeolian ridges, a type of dune..

WikiESP 036429 1925yardangscrater.jpg|Yardangs near a crater, as seen by HiRISE under HiWish program Location is in the Amazonis quadrangle.

WikiESP 035558 1830yardang.jpg|Yardangs, as seen by HiRISE under HiWish program Location is near Gordii Dorsum in the Amazonis quadrangle. These yardangs are in the upper member of the Medusae Fossae Formation.

35558 1830yardangs.jpg|Yardangs, as seen by HiRISE under HiWish program Location is near Gordii Dorsum in the Amazonis quadrangle. Note: this is an enlargement of previous image.

35558 1830yardangsclose.jpg|Yardangs, as seen by HiRISE under HiWish program Location is near Gordii Dorsum in the Amazonis quadrangle. Note: this is an enlargement of previous image.

Wikiesp036510 1735layersyardang.jpg|Yardangs showing layers, as seen by HiRISE under HiWish program Location is Aeolis quadrangle.

ESP 044777 1725yardangs.jpg|Wide view of yardangs, as seen by HiRISE under HiWish program Location is Memnonia quadrangle.

44777 1725yardangs2.jpg|Close view of yardangs in previous image, as seen by HiRISE under HiWish program Location is Memnonia quadrangle.

ESP 047401 1715yardangslayers.jpg|Wide view of yardangs, as seen by HiRISE under HiWish program This image is odd in that the yardangs are lined up in different directions in the top and bottom part of image. The wind direction probably changed to cause this. Location is Memnonia quadrangle.

File:Wide view of field of yardings.jpg|Wide view of yardangs in Arabia quadrangle

File:ESP 061610 1895yardangsclose.jpg|Close view of yardangs in Arabia quadrangle These features are shaped by the wind.