Rupes Tenuis
{{Short description|Martian north polar scarp}}
{{use dmy dates|date=August 2017}}
File:Rupes Tenuis perspective view ESA240369.jpg on the left of the picture. Picture was taken by the Mars Express orbiter of the European Space Agency]]
Rupes Tenuis ({{langx|la|thin cliff}}) is a Martian north polar scarp.{{cite web|title=Tenuis Rupes|url=https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA20607|publisher=NASA}} It is named after one of the classical albedo features on Mars.{{cite web|title=Rupes Tenuis|url=https://planetarynames.wr.usgs.gov/Feature/5231?__fsk=-1096305158|website=Gazetteer of Planetary Nomenclature|publisher=USGS}} Its name was officially approved by IAU in 1988. It extends from latitude 74.94°N to 82.2°N and from longitude 242.12°E to 300.77°E (59.23°W – 117.88°W). Its centre is located at latitude 81.6°N longitude 85.47°W. It marks the outer perimeter of Planum Boreum from longitude 242.12°E to 300.77°E, and it is formed by the eastern extension of the Olympia Cavi, a series of local troughs and depressions, which become longer and deeper as they merge to create the Rupes Tenuis scarp formation.{{cite journal|author1=Kenneth L. Tanaka, J. Alexis P. Rodriguez, James A. Skinner Jr., Mary C. Bourke, Corey M. Fortezzo, Kenneth E. Herkenhoff, Eric J. Kolb, Chris H. Okubo|title=North polar region of Mars: Advances in stratigraphy, structure, and erosional modification|journal=Icarus|volume=196|issue=2|date=28 February 2008|pages=318–358|doi=10.1016/j.icarus.2008.01.021|url=https://www.researchgate.net/publication/235137809|access-date=25 August 2017|ref=YICAR 8602|bibcode=2008Icar..196..318T}} The scarp is located to the west of Chasma Boreale, at the base of Planum Boreum,{{cite web|author1=Kenneth L. Tanaka, James A. Skinner, Jr., and Trent M. Hare|title=Geologic Map of the Northern Plains of Mars|url=https://pubs.usgs.gov/sim/2005/2888/sim2888pamphlet.pdf|publisher=USGS}} and its height varies from a few hundred metres to a maximum of approximately 1000 metres.{{cite web|author1=Kenneth L. Tanaka and Corey M. Fortezzo|title=Geologic Map of the North Polar Region of Mars|url=https://pubs.usgs.gov/sim/3177/sim3177_pamphlet.pdf|publisher=USGS}}{{cite book|author=Matthew R. Balme|title=Martian Geomorphology|url=https://books.google.com/books?id=F_cvPNj6f5MC&pg=PA257|year=2011|publisher=Geological Society of London|isbn=978-1-86239-330-1|page=257}}
Local topography
File:USGS-Mars-MC-1 Map of Planum Boreum cropped.jpg
Immediately to the south of Rupes Tenuis, approximately at 285ºE,{{cite web|author1=T. C. Brothers, J. W. Holt, A. Spiga|title=ABALOS MENSA, PLANUM BOREUM, MARS: A CONSTRUCTIONAL, AEOLIAN HISTORY DERIVED FROM RADAR AND OPTICAL STRATIGRAPHY, REINFORCED BY ATMOSPHERIC MODELING.|url=http://www.lpi.usra.edu/meetings/lpsc2012/pdf/1452.pdf|website=43rd Lunar and Planetary Science Conference (2012)}} lies Abalos Mensa, a convex formation of approximately 180 kilometer span, shaped like a wedge when viewed from above. The dune field of Abalos Undae continues in a southwestward direction after it emerges from the western end of a narrow channel separating Rupes Tenuis from Abalos Mensa.
Two named craters are located in the immediate area of Rupes Tenuis; Crotone, located at 82.2ºN, 290.0ºE with a 6.4 km diameter, is situated at the channel separating the scarp from Abalos Mensa, and Boola, located at 81.1ºN, 254.2ºE, with a 17 km diameter, is found close to the western boundary of the Rupes Tenuis scarp. West of Abalos Mensa, parallel to and south of the Rupes Tenuis scarp, runs a narrow, low-altitude plain, named Tenuis Mensa, which exhibits a southward slope.
Erosion characteristics
File:PSP 010171 2630 MIRB Upper Rupes Tenuis Unit Exposed Northwest of Crotone Crater.jpg
The proposed erosion mechanism for the polar basal unit in general, and Rupes Tenuis in particular, are katabatic winds (From Greek: katabasis, "descent", i.e. strong winds descending from Planum Boreum), and solar ablation. These mechanisms are also considered responsible for the modern-day erosion and retreat of the Rupes Tenuis scarp, the existence of conical mounds and promontories in the immediate vicinity of the scarp, and the creation of the narrow channels that separate Abalos Mensa from the scarp. This erosion process is theorised to have existed since the Late Amazonian period on Mars, and it is considered to have contributed to the continuous retreat of the polar scarp from an older southern latitude as low as 74ºN.
It is further theorised that the Rupes Tenuis stratigraphic unit may have been a paleo-plateau that descended further South than the present-day Rupes Tenuis scarp. Geological formations in the vicinity of the scarp, such as mounds, are considered to have been formed by erosion mechanisms rather than volcanic activity. The horizontal attitude (inclination) of the layers of the Rupes Tenuis unit, further indicates the non-volcanic origin of these formations, since layers of volcanic origin are not typically horizontal. Nearby formations such as Abalos Colles — a group of five, flat or concave top, mounds, less than 700 m high and less than 1 km in diameter — are considered to be erosional remnants of a once-continuous stratigraphic unit, the Rupes Tenuis unit.
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Images by NASA and ESA
File:Rupes Tenuis ESA214031.jpg|The Rupes Tenuis scarp with Abalos Mensa at the top of the picture. Picture was taken by the Mars Express orbiter of the European Space Agency
File:ESP 028303 2620 RED.NOMAP Rupes Tenuis.jpg|Rupes Tenuis scarp
File:PSP 009012 2610 MIRB Boola Crater Ejecta Exposed on Rupes Tenuis.jpg|Boola crater ejecta exposed on Rupes Tenuis
File:PIA20607 Rupes Tenuis scarp.jpg|Rupes Tenuis is the strip in the middle of the image. The polar cap is on the top side of the image with the lower elevation at the bottom.
File:PSP 009406 2600 MIRB Exposed Rupes Tenuis of the Southern Margin of Hyperborea Lingula.jpg|Exposed Rupes Tenuis of the southern margin of Hyperborea Lingula
File:ESP 028369 2615 MIRB Rupes Tenuis.jpg|Rupes Tenuis
File:PSP 010092 2625 MIRB Basal Rupes Tenuis Unit Exposed North of Abalos Mensa.jpg|Basal Rupes Tenuis unit exposed north of Abalos Mensa
File:ESP 019454 2610 MIRB Contact between Rupes Tenuis Scarp and Buried Polygon.jpg|Contact between Rupes Tenuis scarp and buried polygon
File:ESP 027498 2625 MRGB Rupes Tenuis Promontory.jpg|Rupes Tenuis Promontory
File:ESP 028303 2620 MIRB Rupes Tenuis.jpg|Rupes Tenuis
File:ESP 028237 2620 MIRB Rupes Tenuis.jpg|Rupes Tenuis
File:ESP 017793 2625 MIRB Interaction between Abalos Mensa and Rupes Tenuis Dunes.jpg|Interaction between Abalos Mensa and Rupes Tenuis dunes
File:ESP 046170 2615 MIRB. Rupes Tenuis Scarp.jpg|Rupes Tenuis scarp
File:ESP 017832 2625 MIRB Basal Rupes Tenuis Unit Exposed North of Abalos Mensa.jpg|Basal Rupes Tenuis unit exposed north of Abalos Mensa
File:ESP 034500 2620 RED North Polar Scarp in Abalos Undae with Basal Exposure and Dunes black and white.jpg|North Polar scarp in Abalos Undae with basal exposure and dunes
File:ESP 034500 2620 RED North Polar Scarp in Abalos Undae with Basal Exposure and Dunes black and white with scale.jpg|North Polar scarp in Abalos Undae with basal exposure and dunes and distance scale
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References
{{reflist|30em}}
{{Geography of Mars}}
{{Portal bar|Solar System}}