{{Short description|Colles on Mars}} {{Infobox feature on celestial object |name = Astapus Colles |image = Astapus Colles.JPG |caption = Astapus Colles Mounds and Knobs, as seen by [[HiRISE]]. Scale bar is 500 meters long. |coordinates = {{coord|35.5|N|272.3|W|globe:mars_type:landmark|display=inline,title}} }} '''Astapus Colles''' is a group of hills in the [[Casius quadrangle]] of Mars, located at 35.5 North and 272.3 West. It is 580 km across and was named after an albedo feature at 35N, 269W.<ref>{{cite web |url=https://planetarynames.wr.usgs.gov/ |title=Home |website=planetarynames.wr.usgs.gov}}</ref> The term "Colles" is used for small hills or knobs.<ref>{{Cite web|url=https://planetarynames.wr.usgs.gov/DescriptorTerms|title = Planetary Names: Feature Types}}</ref>
== Geology == Astapus Colles is 80 km thick and rich in ice. It mostly lies on top of the [[Vastitas Borealis]] interior unit, although it also overlies portions of the Vastitas Borealis marginal unit;<ref name=":0">{{Cite journal|date=2009-07-01|title=Stratigraphical evidence of late Amazonian periglaciation and glaciation in the Astapus Colles region of Mars|url=https://www.sciencedirect.com/science/article/abs/pii/S0019103509000712|journal=Icarus|language=en|volume=202|issue=1|pages=17–21|doi=10.1016/j.icarus.2009.02.009|issn=0019-1035|last1=Soare|first1=Richard J.|last2=Osinski|first2=Gordon R.|bibcode=2009Icar..202...17S|url-access=subscription}}</ref> both of these units together make up the greater Vastitas Borealis region.<ref>{{Cite journal|last1=Salvatore|first1=M. R.|last2=Christensen|first2=P. R.|date=2015-03-01|title=Origin and Evolution of the Vastitas Borealis Formation in the Vicinity of Chryse and Acidalia Planitiae, Mars|journal=46th Annual Lunar and Planetary Science Conference|url=http://adsabs.harvard.edu/abs/2015LPI....46.1457S|volume=46|issue=1832|pages=1457|bibcode=2015LPI....46.1457S}}</ref> Features of Astapus Colles are both [[Glacial landform|glacial]] and [[Periglaciation|periglacial]] in nature, including scalloped depressions, rimless depressions, [[Polygonal patterned ground|polygonal ground]],<ref>{{Cite journal|date=1995-03-01|title=Outwash Plains and Thermokarst on Mars|url=https://www.sciencedirect.com/science/article/abs/pii/S0019103585710469|journal=Icarus|language=en|volume=114|issue=1|pages=93–112|doi=10.1006/icar.1995.1046|issn=0019-1035|last1=Costard|first1=F.M.|last2=Kargel|first2=J.S.|bibcode=1995Icar..114...93C|url-access=subscription}}</ref><ref>{{Cite journal|last1=Morgenstern|first1=Anne|last2=Hauber|first2=Ernst|last3=Reiss|first3=Dennis|last4=van Gasselt|first4=Stephan|last5=Grosse|first5=Guido|last6=Schirrmeister|first6=Lutz|date=2007-06-28|title=Deposition and degradation of a volatile-rich layer in Utopia Planitia and implications for climate history on Mars|journal=Journal of Geophysical Research|volume=112|issue=E6|doi=10.1029/2006je002869|bibcode=2007JGRE..112.6010M|issn=0148-0227|doi-access=free}}</ref> raised rims, and potentially [[pingo]]s and pingo scars.<ref>{{Cite journal|date=2009-05-01|title=Mesoscale raised rim depressions (MRRDs) on Earth: A review of the characteristics, processes, and spatial distributions of analogs for Mars|url=https://www.sciencedirect.com/science/article/abs/pii/S0032063308004054|journal=Planetary and Space Science|language=en|volume=57|issue=5–6|pages=579–596|doi=10.1016/j.pss.2008.11.011|issn=0032-0633|last1=Burr|first1=Devon M.|last2=Bruno|first2=Barbara C.|last3=Lanagan|first3=Peter D.|last4=Glaze|first4=Lori S.|last5=Jaeger|first5=Windy L.|last6=Soare|first6=Richard J.|last7=Wan Bun Tseung|first7=Jean-Michel|last8=Skinner|first8=James A.|last9=Baloga|first9=Stephen M.|bibcode=2009P&SS...57..579B|url-access=subscription}}</ref><ref>{{Cite journal|date=2009-01-01|title=Possible pingo fields in the Utopia basin, Mars: Geological and climatical implications|url=https://www.sciencedirect.com/science/article/abs/pii/S0019103508003278|journal=Icarus|language=en|volume=199|issue=1|pages=49–74|doi=10.1016/j.icarus.2008.09.007|issn=0019-1035|last1=Depablo|first1=M.|last2=Komatsu|first2=G.|bibcode=2009Icar..199...49D|url-access=subscription}}</ref>
== Formation == Astapus Colles was formed in the late [[Amazonian (Mars)|Amazonian period]]. The region encompassing Astapus Colles is believed to be an early-Amazonian icy mantle that has since been modified by periglacial freeze-thaw cycles; Astapus Colles was then formed later, on top of this mantle, by glacial accumulation and ablation. These processes were facilitated by atmospheric deposition and sublimation, respectively. Because the periglacial processes have also influenced the surrounding regions, the higher abundance of craters in those regions implies they were formed earlier than Astapus Colles, and thus the periglacial processes must have happened first. The glacial processes then created Astapus Colles and eroded the local craters.<ref name=":0" />
==References== {{commons category|Astapus Colles}} {{reflist}}
{{Geography of Mars}}
[[Category:Casius quadrangle]] [[Category:Hills on Mars]]