View source for Astronomy:Argyre quadrangle

{{Short description|Map of Mars}}
{{Infobox feature on celestial object
|name        = Argyre [[Earth:Quadrangle (geography)|quadrangle]]
|image       = [[File:USGS-Mars-MC-26-ArgyreRegion-mola.png|300px]]
|caption     = Map of Argyre quadrangle from [[Astronomy:Mars Orbiter Laser Altimeter|Mars Orbiter Laser Altimeter]] (MOLA) data. The highest elevations are red and the lowest are blue.
|coordinates = {{coord|47.5|S|30|W|globe:mars_type:landmark|display=inline,title}}
}}
[[File:Argyre region on Mars by the Viking 1 orbiter.jpg|thumb|300px|Image of the Argyre Quadrangle (MC-26). The west-central part contains the Argyre basin, defined by a rim of rugged mountain blocks that surrounds a nearly circular expanse of light-colored plains. The large basin is surrounded by heavily cratered highlands.]]
The '''Argyre  [[Earth:Quadrangle (geography)|quadrangle]]''' is one of a series of [[Astronomy:List of quadrangles on Mars|30 quadrangle maps of Mars]] used by the United States Geological Survey (USGS) [[Earth:Astrogeology Research Program|Astrogeology Research Program]]. The Argyre  quadrangle is also referred to as MC-26 (Mars Chart-26).<ref>Davies, M.E.; Batson, R.M.; Wu, S.S.C. "Geodesy and Cartography" in Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; Matthews, M.S., Eds. ''Mars.'' University of Arizona Press: Tucson, 1992.</ref>  It contains [[Astronomy:Argyre Planitia|Argyre Planitia]] and part of [[Astronomy:Noachis Terra|Noachis Terra]].

==Name==
The word Argyre is named after a legendary silver at the mouth of the Ganges--[Arakan, Berma.<ref>Blunck, J.  1982.  Mars and its Satellites.  Exposition Press.  Smithtown, N.Y.</ref>
{{Main|Astronomy:Classical albedo features on Mars}}

The '''Argyre quadrangle''' covers the area from 0° to 60° west longitude and from 30° to 65° south latitude on [[Astronomy:Mars|Mars]].  It contains [[Astronomy:Galle (Martian crater)|Galle crater]], which resembles a [[Smiley|smiley face]] and the [[Astronomy:Argyre Planitia|Argyre basin]], a giant impact crater.  Research published in the journal ''Icarus'' has found pits in Hale Crater that are caused by hot ejecta falling on ground containing ice.  The pits are formed by heat forming steam that rushes out from groups of pits simultaneously, thereby blowing away from the pit ejecta.<ref>{{cite journal | last1 = Tornabene | first1 = L. |display-authors=et al | year = 2012 | title = Widespread crater-related pitted materials on Mars. Further evidence for the role of target volatiles during the impact process | journal = Icarus | volume = 220 | issue = 2| pages = 348–368 | doi=10.1016/j.icarus.2012.05.022 | bibcode=2012Icar..220..348T}}</ref>
Many steep slopes in this quadrangle contain gullies, which are believed to have formed by relatively recent flows of water.

==Martian gullies==
Gullies are common in some latitude bands on Mars.  Usually, martian gullies are found on the walls of craters or troughs, but [[Astronomy:Charitum Montes|Charitum Montes]], a group of mountains, has gullies in some areas (See the image below).

Gullies occur on steep slopes, especially on the walls of craters. Gullies are believed to be relatively young because they have few, if any craters. Moreover, they lie on top of sand dunes which themselves are considered to be quite young. Usually, each gully has an alcove, channel, and apron. Some studies have found that gullies occur on slopes that face all directions,<ref>Edgett, K. et al. 2003.  Polar-and middle-latitude martian gullies:  A view from MGS MOC after 2 Mars years in the mapping orbit.  ''Lunar Planet. Sci.'' 34.  Abstract 1038.</ref> others have found that the greater number of gullies are found on poleward facing slopes, especially from 30 to 44 S.<ref name="planetary.brown.edu">{{cite web |url=http://www.planetary.brown.edu/pdfs/3138.pdf |title=Archived copy |website=www.planetary.brown.edu |access-date=22 May 2022 |archive-url=https://web.archive.org/web/20081006060452/http://www.planetary.brown.edu/pdfs/3138.pdf |archive-date=6 October 2008 |url-status=dead}}</ref><ref name="ReferenceB">{{cite journal | last1 = Dickson | first1 = J.|display-authors=et al | year = 2007 | title = Martian gullies in the southern mid-latitudes of Mars Evidence for climate-controlled formation of young fluvial features based upon local and global topography | journal = Icarus | volume = 188 | issue = 2| pages = 315–323 | doi=10.1016/j.icarus.2006.11.020 | bibcode=2007Icar..188..315D}}</ref>

Although many ideas have been put forward to explain them,<ref>{{cite web|url=http://www.psrd.hawaii.edu/Aug03/MartianGullies.html|title=PSRD: Gullied Slopes on Mars|access-date=26 December 2014}}</ref> the most popular involve liquid water coming from an [[Earth:Aquifer|aquifer]], from melting at the base of old glaciers, or from the melting of ice in the ground when the climate was warmer.<ref name="ReferenceA">{{cite journal | last1 = Heldmann | first1 = J. | last2 = Mellon | first2 = M. | year = 2004 | title = Observations of martian gullies and constraints on potential formation mechanisms | url = https://zenodo.org/record/1259029| journal = Icarus | volume = 168 | issue = 2| pages = 285–304 | doi=10.1016/j.icarus.2003.11.024 | bibcode=2004Icar..168..285H}}</ref><ref>Forget, F. et al. 2006. Planet Mars Story of Another World. Praxis Publishing. Chichester, UK.</ref> Because of the good possibility that liquid water was involved with their formation and that they could be very young, scientists are excited. Maybe the gullies are where we should go to find life.

There is evidence for all three theories. Most of the gully alcove heads occur at the same level, just as one would expect of an [[Earth:Aquifer|aquifer]]. Various measurements and calculations show that liquid water could exist in aquifers at the usual depths where gullies begin.<ref name="ReferenceA"/> One variation of this model is that rising hot [[Biology:Magma|magma]] could have melted ice in the ground and caused water to flow in aquifers. Aquifers are layer that allow water to flow. They may consist of porous sandstone. The aquifer layer would be perched on top of another layer that prevents water from going down (in geological terms it would be called impermeable). Because water in an aquifer is prevented from going down, the only direction the trapped water can flow is horizontally. Eventually, water could flow out onto the surface when the aquifer reaches a break—like a crater wall. The resulting flow of water could erode the wall to create gullies.<ref>{{cite web|url=http://www.space.com/scienceastronomy/mars_aquifer_041112.html|title=Mars Gullies Likely Formed By Underground Aquifers|work=Space.com|date=12 November 2004|access-date=26 December 2014}}</ref> Aquifers are quite common on Earth. A good example is "Weeping Rock" in Zion National Park Utah.<ref>Harris, A and E. Tuttle. 1990. Geology of National Parks. Kendall/Hunt Publishing Company. Dubuque, Iowa</ref>

As for the next theory, much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust.<ref>{{cite journal | last1 = Malin | first1 = M. | last2 = Edgett | first2 = K. | s2cid = 129376333 | year = 2001 | title = Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission | journal = J. Geophys. Res. | volume = 106 | issue = E10| pages = 23429–23570 | doi=10.1029/2000je001455 | bibcode=2001JGR...10623429M| doi-access = free }}</ref><ref>{{cite journal | last1 = Mustard | first1 = J.|display-authors=et al | year = 2001 | title = Evidence for recent climate change on Mars from the identification of youthful near-surface ground ice | journal = Nature | volume = 412 | issue = 6845| pages = 411–414 | doi=10.1038/35086515 | pmid=11473309 | bibcode = 2001Natur.412..411M| s2cid = 4409161}}</ref><ref>{{cite journal | last1 = Carr | first1 = M | year = 2001 | title = Mars Global Surveyor observations of fretted terrain | journal = J. Geophys. Res. | volume = 106 | issue = E10| pages = 23571–23595 | doi=10.1029/2000je001316 | bibcode=2001JGR...10623571C}}</ref> This ice-rich mantle, a few yards thick, smooths the land, but in places it has a bumpy texture, resembling the surface of a basketball. The mantle may be like a glacier and under certain conditions the ice that is mixed in the mantle could melt and flow down the slopes and make gullies.<ref>{{cite web|url=http://www.nbcnews.com/id/15702457|title=Martian gullies could be scientific gold mines|work=NBC News|access-date=26 December 2014}}</ref><ref>{{cite journal|title=Formation of gullies on Mars: Link to recent climate history and insolation microenvironments implicate surface water flow origin| doi=10.1073/pnas.0803760105|pmid=18725636|volume=105|issue=36|pmc=2734344|date=September 2008|journal=Proc. Natl. Acad. Sci. U.S.A.|pages=13258–63 | last1 = Head | first1 = JW | last2 = Marchant | first2 = DR | last3 = Kreslavsky | first3 = MA|bibcode=2008PNAS..10513258H| doi-access=free}}</ref><ref>{{cite journal | last1 = Head | first1 = J. |display-authors=et al | year = 2008 | title = Formation of gullies on Mars: Link to recent climate history and insolation microenvironments implicate surface water flow origin | journal = PNAS | volume = 105 | issue = 36| pages = 13258–13263 | doi=10.1073/pnas.0803760105 | pmid=18725636 | pmc=2734344| bibcode = 2008PNAS..10513258H | doi-access = free }}</ref>  Because there are few craters on this mantle, the mantle is relatively young. An excellent view of this mantle is shown below in the picture of the Ptolemaeus Crater Rim, as seen by HiRISE.<ref>{{cite journal | last1 = Christensen | first1 = P | year = 2003 | title = Formation of recent martian gullies through melting of extensive water-rich snow deposits | journal = Nature | volume = 422 | issue = 6927| pages = 45–48 | doi=10.1038/nature01436 | pmid=12594459| bibcode = 2003Natur.422...45C| s2cid = 4385806 }}</ref>
The ice-rich mantle may be the result of climate changes.<ref>{{cite web|url=http://news.nationalgeographic.com/news/2008/03/080319-mars-gullies_2.html|archive-url=https://web.archive.org/web/20080504022016/http://news.nationalgeographic.com/news/2008/03/080319-mars-gullies_2.html|url-status=dead|archive-date=May 4, 2008|title=Melting Snow Created Mars Gullies, Expert Says|access-date=26 December 2014}}</ref> Changes in Mars's orbit and tilt cause significant changes in the distribution of water ice from polar regions down to latitudes equivalent to Texas. During certain climate periods water vapor leaves polar ice and enters the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. The atmosphere of Mars contains a great deal of fine dust particles. Water vapor will condense on the particles, then fall down to the ground due to the additional weight of the water coating. When Mars is at its greatest tilt or obliquity, up to 2&nbsp;cm of ice could be removed from the summer ice cap and deposited at midlatitudes. This movement of water could last for several thousand years and create a snow layer of up to around 10 meters thick.<ref>{{cite journal | last1 = Jakosky | first1 = B. | last2 = Carr | first2 = M. | year = 1985 | title = Possible precipitation of ice at low latitudes of Mars during periods of high obliquity | url = https://zenodo.org/record/1233025| journal = Nature | volume = 315 | issue = 6020| pages = 559–561 | doi=10.1038/315559a0 | bibcode=1985Natur.315..559J| s2cid = 4312172 }}</ref><ref>{{cite journal | last1 = Jakosky | first1 = B. |display-authors=et al | year = 1995 | title = Chaotic obliquity and the nature of the Martian climate | journal = J. Geophys. Res. | volume = 100 | issue = E1| pages = 1579–1584 | doi=10.1029/94je02801 | bibcode=1995JGR...100.1579J}}</ref> When ice at the top of the mantling layer goes back into the atmosphere, it leaves behind dust, which insulating the remaining ice.<ref>https://www.sciencedaily.com/releases/2003/12/031218075443.htmAds {{Dead link|date=May 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>  Measurements of altitudes and slopes of gullies support the idea that snowpacks or glaciers are associated with gullies.  Steeper slopes have more shade which would preserve snow.<ref name="planetary.brown.edu"/><ref name="ReferenceB"/>
Higher elevations have far fewer gullies because ice would tend to sublimate more in the thin air of the higher altitude.<ref>{{cite journal | last1 = Hecht | first1 = M | year = 2002 | title = Metastability of liquid water on Mars | journal = Icarus | volume = 156 | issue = 2| pages = 373–386 | doi=10.1006/icar.2001.6794 | bibcode=2002Icar..156..373H}}</ref>

The third theory might be possible since climate changes may be enough to simply allow ice in the ground to melt and thus form the gullies. During a warmer climate, the first few meters of ground could thaw and produce a "debris flow" similar to those on the dry and cold Greenland east coast.<ref>Peulvast, J. Physio-Geo. 18. 87-105.</ref> Since the gullies occur on steep slopes only a small decrease of the shear strength of the soil particles is needed to begin the flow. Small amounts of liquid water from melted ground ice could be enough.<ref>Costard, F. et al. 2001. Debris Flows on Mars: Analogy with Terrestrial Periglacial Environment and Climatic Implications. Lunar and Planetary Science XXXII (2001). 1534.pdf</ref><ref>http://www.spaceref.com:16090/news/viewpr.html?pid=7124 {{Dead link|date=May 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>  Calculations show that a third of a mm of runoff can be produced each day for 50 days of each Martian year, even under current conditions.<ref>{{cite journal | last1 = Clow | first1 = G | year = 1987 | title = Generation of liquid water on Mars through the melting of a dusty snowpack | doi = 10.1016/0019-1035(87)90123-0 | journal = Icarus | volume = 72 | issue = 1| pages = 93–127 | bibcode = 1987Icar...72...95C }}</ref>

<gallery class="center" widths="190px" heights="180px" >
Image:Wikiargyragullies.JPG|Gullies on the western rim of Argyra Planitia as seen with CTX.
Image:Charitum Montes Gullies.JPG|[[Astronomy:Charitum Montes|Charitum Montes]] Gullies, as seen by HiRISE
Image:Green Crater Gullies.jpg|Gullies in Green Crater, as seen by HiRISE.
Image:Close-up of Green Crater Gullies.JPG|Close-up of gullies in Green Crater, as seen by HiRISE.
Image:Jezza Crater.JPG|Jezza Crater, as seen by HiRISE. North wall (at top) has gullies.  Dark lines are dust devil tracks. Scale bar is 500 meters long.
Image:ESP 022685 dunesandgullieslabeled.jpg|Gullies, as seen by HiRISE under HiWish program.  Location is Nereidum Montes.
Image:24808multilevelgullies.jpg|Scene in Argyre quadrangle with gullies, alluvival fans, and hollows, as seen by HiRISE under [[Astronomy:HiWish program|HiWish program]].  Enlargements of parts of this image are below.
Image:24808multiplefans.jpg|Several levels of alluvial fans, as seen by HiRISE under HiWish program.  Locations of these fans are indicated in the previous image.
Image:24808smallfan.jpg|Small, well-formed alluvial fan, as seen by HiRISE under HiWish program.  Location of this fan is shown in an image displayed above.
Image:24808hollows.jpg|Enlargement of above image showing hollows with box showing the size of a football field, as seen by HiRISE under HiWish program.
Image:28540gullies.jpg|Gullies as seen by HiRISE under HiWish program.
File:ESP 028896 1355gullies.jpg|Gullies in [[Astronomy:Nereidum Montes|Nereidum Montes]], as seen by HiRISE under HiWish program.
ESP 039919 1375gullies.jpg|Gullies in a crater, as seen by HiRISE under HiWish program
ESP 039919 1375aprons.jpg|Close up of gully aprons, as seen by HiRISE under HiWish program  Note this is an enlargement of the previous image of gullies in a crater.
ESP 040974 1395gullies.jpg|Wide view of gullies in Arkhangelsky Crater, as seen by HiRISE under HiWish program
40974 1395gullies.jpg|Close-up of small channels in gullies in Arkhangelsky Crater, as seen by HiRISE under HiWish program  [[Earth:Patterned ground|Patterned ground]] in the shape of polygons can be seen to the right.  Note: this is an enlargement of the previous image from Arkhangelsky Crater.
40974 1395gully.jpg|Close-up of a gully showing a channel going across the apron, as seen by HiRISE under HiWish program.   Note: this is an enlargement of a previous image from Arkhangelsky Crater.
ESP 047395 1415gulliesridges.jpg|Gullies in crater, as seen by HiRISE under HiWish program
47395 1415gullycurvedchannels.jpg|Close view of gullies from previous image  The channels are quite curved.  Because channels of gullies often form curves, it was thought that they were made by flowing water.  Today, it is thought that they could be produced with chunks of dry ice.  The image is from HiRISE under HiWish program.
ESP 047528 1355gullies.jpg|Gullies on two sides of a mound, as seen by HiRISE under HiWish program
 
File:ESP 047963 1305gullies.jpg|Gullies, as seen by HiRISE under HiWish program
47963 1305gullychannelclose.jpg|Close view of gully channel, as seen by HiRISE under HiWish program  Arrow shows small channel within larger channel.  Small channel is quite curved in this image.
</gallery>

==Argyre basin==
The [[Astronomy:Argyre Planitia|Argyre basin]] was created by a giant impact that occurred 70 million years after the Hellas impact.<ref>{{cite journal | last1 = Robbins |display-authors=et al | year = 2013 | title = large impact crater histories of Mars: The effect of different model crater age techniques | journal = Icarus | volume = 225 | issue = 1| pages = 173–184 | doi=10.1016/j.icarus.2013.03.019 | bibcode=2013Icar..225..173R}}</ref>  It is believed to have contained a lake early in the history of Mars.<ref>Parker, T. et al. 2000.  Argyre Planitia and the Mars global hydrolocia cycle.  LPSC XXXI.  Abstract 2033</ref> At least three river valleys (Surius Vallis, Dzigal Vallis, and Palacopus Vallis) drain into it from the south.  After it froze solid, the ice formed eskers which are visible today.<ref>Kargel, J. and R. Strom.  1991.  Terrestrial glacial eskers:  analogs for martian sinuous ridges.  LPSC XXII, 683-684.</ref><ref name="Carr2006">{{cite book|author=Michael H. Carr|title=The surface of Mars|url=https://books.google.com/books?id=uLHlJ6sjohwC|access-date=21 March 2011|year=2006|publisher=Cambridge University Press|isbn=978-0-521-87201-0}}</ref>  An article written by 22 researchers in Icarus concluded that the impact that formed the Argyre basin probably stuck an ice cap or a thick [[Earth:Permafrost|permafrost]] layer.  Energy from the impact melted the ice and formed a giant lake that eventually sent water to the North.  The lakes's volume was equal to that of Earth's Mediterranean Sea.  The deepest part of the lake may have taken more than a hundred thousand years to freeze, but with the help of heat from the impact, geothermal heating, and dissolved solutes it may have had liquid water for many millions of years.  Life may have developed in this time.  This region shows a great deal of evidence of glacial activity with flow features, crevasse-like fractures, [[Earth:Drumlin|drumlin]]s, [[Earth:Esker|esker]]s, tarns, aretes, cirques, horns, U-shaped valleys, and terraces.  Because of the shapes of Argyre sinuous ridges, the authors concluded that they are eskers.<ref>{{cite journal | last1 = Dohm | first1 = J. | last2 = Hare | first2 = T. | last3 = Robbins | first3 = S. | last4 = Williams | first4 = J.-P. | last5 = Soare | first5 = R. | last6 = El-Maarry | first6 = M. | last7 = Conway | first7 = S. | last8 = Buczkowski | first8 = D. | last9 = Kargel | first9 = J. | last10 = Banks | first10 = M. | last11 = Fairén | first11 = A. | last12 = Schulze-Makuch | first12 = D. | last13 = Komatsu | first13 = G. | last14 = Miyamoto | first14 = H. | last15 = Anderson | first15 = R. | last16 = Davila | first16 = A. | last17 = Mahaney | first17 = W. | last18 = Fink | first18 = W. | last19 = Cleaves | first19 = H. | last20 = Yan | first20 = J. | last21 = Hynek | first21 = B. | last22 = Maruyama | first22 = S. | year = 2015 | title = Geological and hydrological histories of the Argyre province, Mars | journal = Icarus | volume = 253 | pages = 66–98 | doi=10.1016/j.icarus.2015.02.017 | bibcode=2015Icar..253...66D| s2cid = 27821086 | url = https://hal-insu.archives-ouvertes.fr/insu-02274347/file/Dohm%20et%20al.%20Argyre_basin_MS_1_31_2015_track-changed_final%20version_finali....pdf }}</ref>  Studies with advanced cameras, such as  CTX, and MRO High Resolution Imaging Science Experiment (HiRISE) suggests that these ridges are probably eskers.<ref>{{cite journal | last1 = Banks | first1 = M. | last2 = Lang | first2 = N. | last3 = Kargel | first3 = J. | last4 = McEwen | first4 = A. | last5 = Baker | first5 = V. | last6 = Grant | first6 = J. | last7 = Pelletier | first7 = J. | last8 = Strom | first8 = R. | year = 2009 | title = An analysis of sinuous ridges in the southern Argyre Planitia, Mars using HiRISE and CTX images and MOLA data | doi = 10.1029/2008JE003244 | journal = J. Geophys. Res. | volume =  114| issue = E9| pages = E09003 | bibcode=2009JGRE..114.9003B| doi-access = free }}</ref><ref>{{cite journal | last1 = Bernhardt | first1 = H. | last2 = Hiesinger | first2 = H. | last3 = Reiss | first3 = D. | last4 = Ivanov | first4 = M. | last5 = Erkeling | first5 = G. | year = 2013 | title = Putative eskers and new insights into glacio-fluvial depositional settings southern Argyre Planitia, Mars | journal = Planet. Space Sci. | volume = 85 | pages = 261–278 | doi=10.1016/j.pss.2013.06.022 | bibcode=2013P&SS...85..261B}}</ref>

<gallery class="center" widths="190px" heights="180px" >
Image:Argyre MOLA zoom 64.jpg|Topography of the Argyre basin, the major feature in the Argyre quadrangle.
</gallery>

==[[Astronomy:Galle (Martian crater)|Galle (Martian crater)]]==
<gallery class="center" widths="190px" heights="180px" >
Happy-face1.jpg|Galle Crater, also called Happy-Face Crater, as seen by Mars Global Surveyor
Wikigalleeye.jpg|Part of Galle Crater, as seen by CTX  camera (on Mars Reconnaissance Orbiter).  The right eye and mouth are labeled.  One of two dune fields are labeled as well.
ESP 046684 1280molawide.jpg|Wide view of area around Galle Crater  Colors show elevations.
ESP 046684 1280molaclosergalle.jpg|Region around Galle Crater  Colors show elevations.
ESP 046684 1280molaclosegalle.jpg|Galle Crater  Colors show elevations.  Arrow indicates a layered mound that is enlarged in other images to follow.
ESP 046684 1280gallecontext.jpg|Wide CTX view of part of layered mound.  Parts of this mound are enlarged in HiRISE images that follow.
ESP 046684 1280layerspretty.jpg|HiRISE image from area in previous image  Picture taken under HiWish program.
ESP 046684 1280layersprettybottom.jpg|Layers in mound in Galle Crater, as seen by HiRISE under HiWish program
ESP 046684 1280layersprettymiddle.jpg|Layers in mound in Galle Crater, as seen by HiRISE under HiWish program
ESP 046684 1280layersprettytop.jpg|Layers in mound in Galle Crater, as seen by HiRISE under HiWish program
46684 1280breaking.jpg|Layers breaking up into boulders in Galle Crater, as seen by HiRISE under HiWish program
46684 1280gullies.jpg|Layers and gullies in Galle Crater, as seen by HiRISE under HiWish program
46684 1280layers.jpg|Close view of layers in mound in Galle Crater, as seen by HiRISE under HiWish program
46684 1280mesa.jpg|Layered mesa in mound in Galle Crater, as seen by HiRISE under HiWish program
46684 1280polygons.jpg|Layers and polygons in mound in Galle Crater, as seen by HiRISE under HiWish program
46684 1280wall.jpg|Close view of layers in mound in Galle Crater, as seen by HiRISE under HiWish program
</gallery>
<gallery class="center" widths="190px" heights="180px" >
PSP 003855 1275layerscaptioned.jpg|Unconformities in layers in Galle Crater, as seen by HiRISE  Arrows point to some of the unconformities

</gallery>

==Other craters==
The older a surface is the more craters it will have; therefore the crater density of an area is used to determine the relative age.<ref>{{Cite web|url=http://www.lpi.usra.edu/education/explore/shaping_the_planets/impact-cratering/|title = Shaping the Planets: Impact Cratering|website=Lpi.usra.edu}}</ref>  
Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits.  As craters get larger (greater than 10&nbsp;km in diameter) they usually have a central peak.<ref>{{cite web|url=http://www.lpi.usra.edu/publications/slidesets/stones/|title=Stones, Wind, and Ice: A Guide to Martian Impact Craters|website=Lpi.usra.edu|access-date=26 December 2014}}</ref> The peak is caused by a rebound of the crater floor following the impact.<ref name="Kieffer1992">{{cite book|author=Hugh H. Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ|access-date=7 March 2011|year=1992|publisher=University of Arizona Press|isbn=978-0-8165-1257-7}}</ref>  Often, craters with diameters greater than 100&nbsp;km have rings on their floors.  Since so much material is blasted away, the ground readjusts, making circular faults.  When lava flows upward along the faults, rings are produced.<ref>Forget, F. et al.  2006. Planet Mars Story of Another World.  Praxis Publishing.  Chichester, UK</ref>

<gallery class="center" widths="190px" heights="180px" >
Image:Wirtz Crater dunes - hires.jpg|Wirtz Crater Dunes with ripples and frost, as seen by HiRISE.
Image:Bond Crater Floor.JPG|Bond Crater Floor, as seen by HiRISE.
Image:Hartwig crater HiRISE.jpg|Hartwig Crater Floor, as seen by HiRISE.  The scale bar is 500 meters long.  
Image:Baltisk Crater Floor.JPG|Baltisk Crater Floor, as seen by HiRISE. Scale bar is 1000 meters long. Dark dunes are visible at the bottom of image on the left.
Image:Lohse Crater.JPG|Lohse Crater Gullies on Central Peak, as seen by HiRISE.  
Image:Arkhangelsky crater dunes.jpg|Arkhangelsky Crater Dunes, as seen by [[Astronomy:THEMIS|THEMIS]].  Click on image to see possible gullies on central peak.
Wikihalleyeast.jpg|East side of Halley Crater, as seen by CTX camera (on [[Astronomy:Mars Reconnaissance Orbiter|Mars Reconnaissance Orbiter]]). 
Wikihalleydevils.jpg|Floor of Halley Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Thin dark lines are [[Astronomy:Dust devil tracks|dust devil tracks]].  Note: this is an enlargement of the previous image of Halley Crater.
Wikivogelwest.jpg|West side of Vogel Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).
Wikihooke.jpg|Hooke Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Dark places are dunes.
Wikihookedevils.jpg|[[Astronomy:Dust devil tracks|Dust devil tracks]] in and around Hooke Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Note: this is an enlargement of the previous image of Hooke Crater.
Wikihookedunesgullies.jpg|Dunes and gullies in Hooke Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Note: this is an enlargement of a previous image of Hooke Crater.
WikihookedunesESP 027432 1350.jpg|Dunes and [[Astronomy:Dust devil tracks|dust devil tracks]] in Hooke Crater, as seen by HiRISE.  There are also gullies just visible.
Wikijonesfloor.jpg|Fan, layers, and dunes on the floor of Jones Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Note: this is an enlargement of the previous image of Jones Crater.
Wikimaraldi.jpg|Maraldi Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).
Wikimaraldidevils.jpg|Dust devil tracks just outside rim of Maraldi Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Note: this is an enlargement of the previous image of Maraldi Crater.
Wikihelmholtzeast.jpg|East side of [[Astronomy:Helmholtz (Martian crater)|Helmholtz Crater]], as seen by CTX camera (on Mars Reconnaissance Orbiter).
Wikihelmholtzdunesdevils.jpg|Dunes and dust devil tracks in Helmholtz Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Note: this is an enlargement of the previous image of Helmholtz Crater.
Wikiwegener.jpg|Wegener Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).
Wikiwegenerdefrostingdunes.jpg|Wegener Crater showing dunes defrosting, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Dark spots are places where frost has disappeared from the dark dunes.  Note: this is an enlargement of the previous image of Wegener Crater.
Wikivonkarmann.jpg|Von Karman Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).  Dark parts near the top are dunes.
Wikivankarmanndefrostingdunes.jpg|Defrosting dunes in Von Karman Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).   Dark places are where frost has left dark dunes.  Picture taken in the springtime on Mars.  
</gallery>

==Layers==

Layers may be formed by groundwater rising up depositing minerals and cementing sediments.  The hardened layers are consequently more protected from erosion.  This process may occur instead of layers forming under lakes.
Some locations on the Red Planet show groups of layered rocks.<ref>{{cite journal | doi = 10.1555/mars.2005.0002 | title = The sedimentary rocks of Sinus Meridiani: Five key observations from data acquired by the Mars Global Surveyor and Mars Odyssey orbiters | date = 2005 | last1 = Edgett | first1 = Kenneth S. | journal = The Mars Journal | volume = 1 | pages = 5–58|bibcode = 2005IJMSE...1....5E }}</ref><ref>{{cite journal | last1 = Malin | first1 = M. P. | last2 = Edgett | first2 = K. S. | date = 2000 | title = Ancient sedimentary rocks of early Mars | journal = Science | volume = 290 | issue = 5498| pages = 1927–1937 | doi = 10.1126/science.290.5498.1927 | pmid = 11110654 |bibcode = 2000Sci...290.1927M }}</ref>  In some places the layers are arranged into regular patterns.<ref>{{cite journal | doi = 10.1126/science.1161870 | title = Quasi-Periodic Bedding in the Sedimentary Rock Record of Mars | date = 2008 | last1 = Lewis | first1 = K. W. | last2 = Aharonson | first2 = O. | last3 = Grotzinger | first3 = J. P. | last4 = Kirk | first4 = R. L. | last5 = McEwen | first5 = A. S. | last6 = Suer | first6 = T.-A. | journal = Science | volume = 322 | issue = 5907 | pages = 1532–5 | pmid = 19056983 |bibcode = 2008Sci...322.1532L | s2cid = 2163048 | url = https://authors.library.caltech.edu/12528/2/LEWsci08supp.pdf }}</ref><ref>Lewis, K. W., O. Aharonson, J. P. Grotzinger, A. S. McEwen, and R. L. Kirk (2010), Global significance of cyclic sedimentary deposits on Mars, Lunar Planet. Sci., XLI, Abstract 2648.</ref>  It has been suggested that the layers were put into place by volcanoes, the wind, or by being at the bottom of a lake or sea.  Calculations and simulations show that groundwater carrying dissolved minerals would surface in the same locations that have abundant rock layers.  According to these ideas, deep canyons and large craters would receive water coming from the ground.  Many craters in the Arabia area of Mars contain groups of layers.  Some of these layers may have resulted from climate change.

The tilt of the rotational axis of Mars has repeatedly changed in the past.  Some changes are large.  Because of these variations of climate, at times the atmosphere of Mars would have been much thicker and contained more moisture.  The amount of atmospheric dust also has increased and decreased. It is believed that these frequent changes helped to deposit material in craters and other low places. The rising of mineral-rich ground water cemented these materials. The model also predicts that after a crater is full of layered rocks, additional layers will be laid down in the area around the crater. So, the model predicts that layers may also have formed in intercrater regions; layers in these regions have been observed.

Layers can be hardened by the action of groundwater.  Martian ground water probably moved hundreds of kilometers, and in the process it dissolved many minerals from the rock it passed through.  When ground water surfaces in low areas containing sediments, water evaporates in the thin atmosphere and leaves behind minerals as deposits and/or cementing agents. Consequently, layers of dust could not later easily erode away since they were cemented together. On Earth, mineral-rich waters often evaporate forming large deposits of various types of salts and other [[Earth:Mineral|mineral]]s. Sometimes water flows through Earth's aquifers, and then evaporates at the surface just as is hypothesized for Mars.  One location this occurs on Earth is the Great Artesian Basin of {{wipe|Australia}}.<ref>{{cite journal | last1 = Habermehl | first1 = M. A. | year = 1980 | title = The Great Artesian Basin, Australia | journal = J. Austr. Geol. Geophys. | volume = 5 | pages = 9–38 }}</ref>  On Earth the hardness of many [[Earth:Sedimentary rock|sedimentary rock]]s, like [[Earth:Sandstone|sandstone]], is largely due to the cement that was put in place as water passed through.

 <gallery class="center" widths="190px" heights="180px" >
ESP 042597 1320layers.jpg|Layers exposed in [[Astronomy:Nereidum Montes|Nereidum Montes]], as seen by HiRISE under HiWish program  The light-toned layers may contain sulfates which are good for preserving traces of ancient life.
42597 1320layers2.jpg|Close-up of layers from previous image, as seen by HiRISE under HiWish program
ESP 043413 1495layers.jpg|Low, layered mesa, as seen by HiRISE under HiWish program  Arrows point to some layers.
ESP 047410 1235layers.jpg|Layers, as seen by HiRISE under HiWish program
</gallery>

<gallery class="center" widths="190px" heights="180px" >
ESP 048003 1495layers.jpg|Wide view of crater showing layers along wall, as seen by HiRISE under HiWish program
48003 1495layerslight.jpg|Close view of layers in crater wall,  as seen by HiRISE under HiWish program
48003 1495cratermesa.jpg|Layers in mesa on floor of crater,  as seen by HiRISE under HiWish program
</gallery>

==Channels==

There is enormous evidence that water once flowed in river valleys on Mars.<ref>{{cite journal | last1 = Baker | first1 = V. | display-authors = etal | year = 2015 | title = Fluvial geomorphology on Earth-like planetary surfaces: a review | journal = Geomorphology | volume = 245 | pages = 149–182 | doi = 10.1016/j.geomorph.2015.05.002 | pmid = 29176917 | pmc = 5701759 }}</ref><ref>Carr, M.  1996.  in Water on Mars.  Oxford Univ. Press.</ref>  Images of curved channels have been seen in images from Mars spacecraft dating back to the early seventies with the [[Astronomy:Mariner 9|Mariner 9]] orbiter.<ref>Baker, V.  1982.  The Channels of Mars. Univ. of Tex. Press, Austin, TX</ref><ref>{{cite journal | last1 = Baker | first1 = V. | last2 = Strom | first2 = R. | last3 = Gulick | first3 = V. | last4 = Kargel | first4 = J. | last5 = Komatsu | first5 = G. | last6 = Kale | first6 = V. | year = 1991 | title = Ancient oceans, ice sheets and the hydrological cycle on Mars | journal = Nature | volume = 352 | issue = 6336| pages = 589–594 | doi = 10.1038/352589a0 | bibcode = 1991Natur.352..589B | s2cid = 4321529 }}</ref><ref>{{cite journal | last1 = Carr | first1 = M | year = 1979 | title = Formation of Martian flood features by release of water from confined aquifers | journal = J. Geophys. Res. | volume = 84 | pages = 2995–300 | doi = 10.1029/jb084ib06p02995 | bibcode = 1979JGR....84.2995C }}</ref><ref>{{cite journal | last1 = Komar | first1 = P | year = 1979 | title = Comparisons of the hydraulics of water flows in Martian outflow channels with flows of similar scale on Earth | journal = Icarus | volume = 37 | issue = 1| pages = 156–181 | doi = 10.1016/0019-1035(79)90123-4 | bibcode = 1979Icar...37..156K }}</ref>  Indeed, a study published in June 2017, calculated that the volume of water needed to carve all the channels on Mars was even larger than the proposed ocean that the planet may have had.  Water was probably recycled many times from the ocean to rainfall around Mars.<ref>{{Cite web|url=http://spaceref.com/mars/how-much-water-was-needed-to-carve-valleys-on-mars.html|title = How Much Water Was Needed to Carve Valleys on Mars? - SpaceRef| date=5 June 2017 }}</ref><ref>{{cite journal | last1 = Luo | first1 = W. | display-authors = etal | year = 2017 | title = New Martian valley network volume estimate consistent with ancient ocean and warm and wet climate | journal = Nature Communications | volume = 8 | page = 15766 | doi = 10.1038/ncomms15766 | pmid = 28580943 | pmc = 5465386 | bibcode = 2017NatCo...815766L }}</ref>  Many places on Mars show channels of different sizes.  Many of these channels probably carried water, at least for a time.  The climate of Mars may have been such in the past that water ran on its surface.  It has been known for some time that Mars undergoes many large changes in its tilt or obliquity because its two small moons lack the gravity to stabilize it, as the Moon stabilizes Earth; at times the tilt of Mars has even been greater than 80 degrees<ref>{{cite journal | last1 = name | last2 = Touma | first2 = J. | last3 = Wisdom | first3 = J. | year = 1993 | title = The Chaotic Obliquity of Mars | journal = Science | volume = 259 | issue = 5099| pages = 1294–1297 | doi = 10.1126/science.259.5099.1294| pmid = 17732249 | bibcode = 1993Sci...259.1294T| s2cid = 42933021 }}</ref><ref>{{cite journal | last1 = Laskar | first1 = J. | last2 = Correia | first2 = A. | last3 = Gastineau | first3 = M. | last4 = Joutel | first4 = F. | last5 = Levrard | first5 = B. | last6 = Robutel | first6 = P. | year = 2004 | title = Long term evolution and chaotic diffusion of the insolation quantities of Mars | journal = Icarus | volume = 170 | issue = 2| pages = 343–364 | doi = 10.1016/j.icarus.2004.04.005 | bibcode = 2004Icar..170..343L | s2cid = 33657806 }}</ref>

{{Main|Astronomy:Outflow channels}}

<gallery class="center" widths="190px" heights="180px" >
ESP 047265 1415channel.jpg|Channel, as seen by HiRISE under HiWish program
ESP 048043 1460channel.jpg|Channel, as seen by HiRISE under HiWish program
Image:Surface features in Argyre.jpg|Channels in Argyre quadrangle as seen by HiRISE, under the HiWish program.  This is the image of the surface from a single HiRISE image.  The scale bar at the top is 500 meters long.
ESP 050243 1425channel.jpg|Channel, as seen by HiRISE under HiWish program
</gallery>

==Dust devil tracks==
Dust devil tracks can be very pretty.  They are caused by giant dust devils removing bright colored dust from the Martian surface; thereby exposing a dark layer.  Dust devils on Mars have been photographed both from the ground and high overhead from orbit. They have even blown dust off the solar panels of two Rovers on Mars, thereby greatly extending their useful lifetime.<ref>[http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20070412a.html Mars Exploration Rover Mission: Press Release Images: Spirit]. Marsrovers.jpl.nasa.gov. Retrieved on 7 August 2011.</ref> The pattern of the tracks has been shown to change every few months.<ref>{{Cite web|url=https://hirise.lpl.arizona.edu/PSP_005383_1255|title=HiRISE &#124; Dust Devils Dancing on Dunes (PSP_005383_1255)|website=Hirise.lpl.arizona.edu|access-date=16 March 2022}}</ref>  A study that combined data from the [[Engineering:High Resolution Stereo Camera|High Resolution Stereo Camera]] (HRSC) and the [[Engineering:Mars Orbiter Camera|Mars Orbiter Camera]] (MOC) found that some large dust devils on Mars have a diameter of {{convert|700|m}} and last at least 26 minutes.<ref>{{cite journal | last1 = Reiss | first1 = D. | display-authors = etal | year = 2011 | title = Multitemporal observations of identical active dust devils on Mars with High Resolution Stereo Camera (HRSC) and Mars Orbiter Camera (MOC) | journal = Icarus | volume = 215 | issue = 1| pages = 358–369 | doi = 10.1016/j.icarus.2011.06.011 | bibcode = 2011Icar..215..358R }}</ref>

{{Main|Astronomy:Dust devil tracks}}

<gallery class="center" widths="190px" heights="180px" >
ESP 048583 1260devilslayers.jpg|Dust devil tracks and layers, as seen by HiRISE under HiWish program

ESP 048583 1260devilsclosecolor.jpg|Close, color view of dust devil tracks, as seen by HiRISE under HiWish program 
ESP 039919 1375devils.jpg|[[Astronomy:Dust devil tracks|Dust devil tracks]] as seen by HiRISE under HiWish program

File:ESP 057669 1245devils.jpg|Dust devil tracks, as seen by HiRISE under HiWish program
</gallery>

==Dunes==

 <gallery class="center" widths="190px" heights="180px" >
File:ESP 057445 1385dunes.jpg|Wide view of small dune field, as seen by HiRISE under HiWish program

File:57445 1385dunesclose.jpg|Close view of dunes, as seen by HiRISE under HiWish program  Ripples are visible on the dunes.

File:Dune field in ESP 033272 1400 01.jpg|Field of dunes as seen by HiRISE
File:Small group of dunes.jpg|Close view of group of dunes, as seen by HiRISE under HiWish program
File:Single dune in Argyre quadrangle.jpg|Single dune

</gallery>

== Other features in Argyre quadrangle==

 <gallery class="center" widths="190px" heights="180px" >
Image:Argyre Map.JPG|Map of Argyre quadrangle with major features labeled.  [[Astronomy:Galle (Martian crater)|Galle crater]] looks like a smile.

Image:Context image for argyrefeatures.JPG|CTX image showing context for the next image.  A group of channels are visible in this image.
Image:Close-up of Argyrefeatures.JPG|Close-up of surface in Argyre quadrangle, as seen by HiRISE, under the HiWish program.

ESP 048280 1395hollows.jpg|Hollows, as seen by HiRISE under HiWish program

File:ESP 054570 1465pingos.jpg|Possible pingos, as seen by HiRISE under HiWish program  Pingos contain a core of ice.  They are expected to have cracks on their surfaces because water expands when it turns into ice.

</gallery>

<gallery class="center" widths="190px" heights="180px" >
File:ESP 055453 1250iceintroughs.jpg|Wide view of polygons with ice in troughs between polygons, as seen by HiRISE under HiWish program

File:55453 1250icetroughs.jpg|Close view of polygons with ice in troughs between polygons, as seen by HiRISE under HiWish program
File:55453 1250polygonsice.jpg|Close view of polygons with ice in troughs between polygons, as seen by HiRISE under HiWish program

</gallery>

== Other Mars quadrangles ==
{{Mars Quads - By Name}}

== Interactive Mars map ==
{{Mars map}}

==See also==

{{div col|colwidth=30em}}
* [[Astronomy:Climate of Mars|Climate of Mars]]
* Dust Devil Tracks
* HiRISE
* HiWish
* [[Astronomy:Impact crater|Impact crater]] 
* [[Astronomy:Lakes on Mars|Lakes on Mars]]
* [[Astronomy:List of quadrangles on Mars|List of quadrangles on Mars]]
* Martian Gullies
* [[Astronomy:Ore resources on Mars|Ore resources on Mars]]
* [[Earth:Unconformity|Unconformity]]
* [[Astronomy:Water on Mars|Water on Mars]]
{{div col end}}

== References ==
{{reflist|colwidth=30em}}

==External links==
* [http://www.psrd.hawaii.edu/Aug03/MartianGullies.html General review of many of the theories involving the origin of gullies.]
* [http://www.planetary.brown.edu/pdfs/3138.pdf Good review of the history of the discovery of gullies.] {{Webarchive|url=https://web.archive.org/web/20170706040142/http://planetary.brown.edu/pdfs/3138.pdf |date=2017-07-06 }}
* [https://www.youtube.com/watch?v=DGBbke1wJRk Lakes on Mars - Nathalie Cabrol (SETI Talks)]
{{Mars}}

[[Category:Argyre quadrangle| ]]
[[Category:Mars]]

{{Sourceattribution|Argyre quadrangle}}