View source for Glaciers on Mars

{{Mars atlas}}
Article written by Jim Secosky.  Jim is a retired science teacher who has used the Hubble Space Telescope, the Mars Global Surveyor, and HiRISE.


Since the 60’s, as our spacecraft have studied Mars with more and more advanced cameras and other instruments, we have found more and more evidence for glaciers. <ref name="SquyresCarr">cite journal | last1 = Squyres | first1 = S.W. | last2 = Carr | first2 = M.H. | year = 1986 | title = Geomorphic evidence for the distribution of ground ice on Mars | url = | journal = Science | volume = 213 | issue = | pages = 249–253 | doi = 10.1126/science.231.4735.249 | </ref> <ref name="Headetal2010">cite journal | last1 = Head | first1 = J.W. | last2 = Marchant | first2 = D.R. | last3 = Dickson | first3 = J.L. | last4 = Kress | first4 = A.M. | year = 2010 | title = Criteria for the recognition of debris-covered glacier and valley glacier landsystem deposits | url = | journal = Earth Planet. Sci. Lett. | volume = 294 | issue = | pages = 306–320 | doi=10.1016/j.epsl.2009.06.041 | </ref> <ref name="HoltetalSHARAD">cite journal | last1 = Holt | first1 = J.W. | display-authors = 1 | last2 = et al | year = 2008 | title = Radar sounding evidence for buried glaciers in the southern mid-latitudes of Mars | url = | journal = Science | volume = 322 | issue = | pages = 1235–1238 | doi=10.1126/science.1164246 | pmid=19023078|</ref> <ref name="MorganetalDeuteronilus">| last1 = Morgan | first1 = G.A. | last2 = Head | first2 = J.W. | last3 = Marchant | first3 = D.R. | year = 2009 | title = Lineated valley fill (LVF) and lobate debris aprons (LDA) in the Deuteronilus Mensae northern dichotomy boundary region, Mars: Constraints on the extent, age and episodicity of Amazonian glacial events | url = | journal = Icarus | volume = 202 | issue = | pages = 22–38 | doi=10.1016/j.icarus.2009.02.017 |</ref > <ref name="Plautetal">cite journal | last1 = Plaut | first1 = J.J. | last2 = Safaeinili | first2 = A. | last3 = Holt | first3 = J.W. | last4 = Phillips | first4 = R.J. | last5 = Head | first5 = J.W. | last6 = Sue | first6 = R. | last7 = Putzig | first7 = A. | year = 2009 | title = Frigeri Radar evidence for ice in lobate debris aprons in the mid-northern latitudes of Mars | doi = 10.1029/2008gl036379 | journal = Geophys. Res. Lett. | volume = 36 | issue = | page = L02203 | </ref> <ref name="Bakeretal2010">cite journal | last1 = Baker | first1 = D.M.H. | last2 = Head | first2 = J.W. | last3 = Marchant | first3 = D.R. | year = 2010 | title = Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae Fossae, Mars: Evidence for extensive mid-latitude glaciation in the Late Amazonian | url = | journal = Icarus | volume = 207 | issue = | pages = 186–209 | doi=10.1016/j.icarus.2009.11.017 | </ref> <ref name="ArfstromHartmann">cite journal | last1 = Arfstrom | first1 = J. | year = 2005 | title = Terrestrial analogs and interrelationships | url = | journal = Icarus | volume = 174 | issue = | pages = 321–335 | doi=10.1016/j.icarus.2004.05.026 | bibcode=2005Icar..174..321A</ref>  On Mars these glaciers are covered with rock and dust debris a few meters to a few tens of meters thick.<ref> Baker, D. and L. Carter.  2019.  Probing supraglacial debris on Mars 1: Sources, thickness, and stratigraphy.  Icarus.  Volume 319.   Pages 745-769 </ref>    Although Mars today seems too dry for any glaciers, this covering material has protected the underlying ice. <ref name="WilliamsSnowpack">cite journal | last1 = Williams | first1 = K. E. | display-authors = 1 | last2 = et al | year = 2008 | title = Stability of mid-latitude snowpacks on Mars | url = | journal = Icarus | volume = 196 | issue = 2| pages = 565–577 | doi=10.1016/j.icarus.2008.03.017 |</ref> One would think that under today’s conditions any exposed ice would undergo [[sublimation]] and disappear into the thin Martian atmosphere.  That is, it would go directly from a solid to a gas. But, the isulating effect of surface material prevents loss of ice.<ref name="Plautetal" /> <ref name="WilliamsSnowpack" /> <ref name="Head, J. 2005">cite journal | doi = 10.1038/nature03359 | last1 = Head | first1 = J. | date = 2005 | last2 = Neukum | first2 = G. | last3 = Jaumann | first3 = R. | last4 = Hiesinger | first4 = H. | last5 = Hauber | first5 = E. | last6 = Carr | first6 = M. | last7 = Masson | first7 = P. | last8 = Foing | first8 = B. | last9 = Hoffmann | first9 = H. | last10 = Kreslavsky | first10 = M. | last11 = Werner | first11 = S. | last12 = Milkovich | first12 = S. | last13 = Van Gasselt | first13 = S. | last14 = Co-Investigator Team | first14 = The Hrsc | title = Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars | url = | journal=Nature | volume = 434 | issue = 7031| pages = 346–350 | pmid=15772652|</ref> <ref> Head, J., et al.  2009.  Northern mid-latitude glaciation in the Late Amazonian period of Mars:  Criteria for the recognition of debris-covered glacier and valley glacier landsystem deposits.  Earth and Planetary Science Letters.  Doi:10.1016/j.epsl.2009.06.041</ref>

==Water for Future Colonists==

The discovery of ice on Mars is important because future colonists may be able to tap the ice for water.  Besides the obvious uses of water to humans, water can be broken down with electricity to form hydrogen and oxygen.  Hence, people living on Mars could be supplied with oxygen to breathe and hydrogen for fuel.  We have known for many decades that the ice caps, called the polar layered deposits, contain ice, but they are far away from where it is easy to land rockets.   Glaciers on the planet are much closer to the equator and widespread about the planet.   Perhaps, the task of obtaining water will be done with automated machines.  Already scientists here on Earth are building devices that can drill into the ground and melt any ice for water.<ref> https://www.nasa.gov/press-release/nasa-s-mars-ice-challenge-follow-the-water</ref> <ref> ↑ http://triblive.com/news/education/career/13040517-74/cmu-team-finalist-for-nasas-mars-ice-challenge-to-drill-for-water</ref>   Recent studies have sought to determine the nature of these covering layers to find out how best to extract water.<ref> Baker, D., L. Carter.   In press.   Probing supraglacial debris on Mars 1: Sources, thickness, and stratigraphy.  Icarus.  https://doi.org/10.1016/j.icarus.2018.09.001</ref>  Our advanced cameras on satellites orbiting the Red Planet have mapped the exact locations of hundreds of glaciers and glacier-like features that may all contain useable ice.  We know where the water is!
From early on, images from satellites have shown features that resembled glaciers on the Earth.  Of particular significance was the angle at the end of the glacier.  The angle was far steeper than geologic features like landslides.  Large stretches of landscape called “fretted terrain,” after the forehead of someone who worries or frets show signs of glacier activity.  This terrain is characterized by wide, flat floored valleys surrounded by steep cliffs.  The floors contained lines in early Viking photographs.<ref>Squyres, S.  1978.  Martian Fretted Terrain:  Flow of Erosional Debris.  Icarus:  34, 600-613.</ref>   Many isolated mesas are present.  Furthermore, mesas are surrounded by wide aprons of material that today we know to be debris covered glaciers.

==Variety of Glaciers on Mars==

Today, we recognize several types of features that contain ice that is covered with dirt and rocks that keep the ice from disappearing.  These features behave like glaciers.  Concentric crater fill (CCF), lobate debris aprons (LDA), and lineated valley fill (LVF) are their names. 
<ref>https://www.sciencedirect.com.wikipedialibrary.idm.oclc.org/science/article/pii/S0019103520304619#bb0190</ref> <ref>Jawin, E, and J. Head.  2021.  Patterns of late Amazonian deglaciation from the distribution of martian paraglacial features. Icarus.  Volume 355. 114117</ref> <ref> S.W. Squyres.  1979.  The distribution of lobate debris aprons and similar flows on Mars.  J. Geophys. Res. Solid Earth, 84. pp. 8087-8096, 10.1029/JB084iB14p08087</ref> <ref>J.W. Head, G. Neukum, R. Jaumann, H. Hiesinger, E. Hauber, M. Carr, P. Masson, B. Foing, H. Hoffmann, M. Kreslavsky, S. Werner, S. Milkovich, S. van Gasselt, Co-Investigator Team, T.H.  2005.  Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars.  Nature, 434. pp. 346-351</ref>  <ref>J.W. Head, D.R. Marchant, J.L. Dickson, A.M. Kress, D.M. Baker.  2010.  Northern mid-latitude glaciation in the late Amazonian period of Mars: criteria for the recognition of debris-covered glacier and valley glacier landsystem deposits
Earth Planet. Sci. Lett., 294.  pp. 306-320</ref> <ref> D.M.H. Baker, J.W. Head, D.R. Marchant.  2010.  Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae fossae, Mars: evidence for extensive mid-latitude glaciation in the late Amazonian.  Icarus, 207 (2010), pp. 186-209, 10.1016/j.icarus.2009.11.017</ref> <ref>J.S. Levy, J.W. Head, D.R. Marchant.  2010.  Concentric crater fill in the northern mid-latitudes of Mars: formation processes and relationships to similar landforms of glacial origin.  Icarus.   209.   pp. 390-404, 10.1016/j.icarus.2010.03.036</ref>  Viscous Flow Features (VFF) is a general term that applies to all of these.<ref>https://www-sciencedirect-com.wikipedialibrary.idm.oclc.org/science/article/pii/S0019103520305091</ref> <ref>Berman, D., et al.  2021.  Ice-rich landforms of the southern mid-latitudes of Mars: A case study in Nereidum Monte.  Icarus.  Icarus.  Volume 355.  114170</ref> <ref>Milliken R.E., Mustard J.F., Goldsby D.L.
Viscous flow features on the surface of Mars: Observations from high-resolution Mars Orbiter Camera (MOC) images
J. Geophys. Res.: Planets, 108 (E6) (2003), p. 5057, 10.1029/2002je002005</ref>

==Glaciers that look like glaciers==


<gallery class="center"  widths="380px" heights="360px">
File:ESP 018857 2225alpineglacier.jpg |Alpine glacier moving from a valley  Lat: 42.2° N Long: 50.5° .  Note how it spreads out when leaving the valley.
File:  Wikielephantglacier.jpg|Glacier in Greenland 
</gallery>

With better cameras, it was observed that some mesas had what resembled glaciers in the valleys.<ref>https://www.uahirise.org/hipod/ESP_077592_2225</ref>   A big advance in understanding Martian geology came when the Mars Orbiter Laser Altimeter (MOLA) on Mars Global Surveyor gave us exact elevations for the whole planet; from then on, we could figure out slopes.  Where the land was tilted, the glacier-forms moved down slope.   Also, researchers observed that when the glacier left the valley and reached a wider, flatter place, it spread out, just as glaciers on Earth do.  In some craters there are large glaciers shaped like giant tongues, so they have been called tongue-shaped glaciers. <ref>Forget, F., et al.  2006.  Planet Mars Story of Another World.  Praxis Publishing, Chichester, UK.   ISBN|978-0-387-48925-4</ref>

[[File:Mars_MGS_colorhillshade_mola_1024.jpg |thumb|300px|center|Topographic map produced with MOLA measurements  This map showed that glacial features move downhill.]]

[[File:Tongueismenius.jpg |thumb|300px|left| Glacier shaped like a giant tongue, as seen by HiRISE under HiWish program ]]

[[File:Glaciers from around Mars 09.jpg|600pxr|Glaciers that look like ones on Earth]]

                          Glaciers that look like ones on Earth

==Lobate Debris Aprons==

So for sure many things look like glaciers, but looks can be deceiving.  Conclusive proof came after radar studies confirmed that many of these features were actually ice with only a thin surface covering.  Shallow Subsurface Radar (SHARD) was the radar system on board the Mars Reconnaissance Orbiter that was used.  It found that features, called lobate debris aprons (LDA’s), around mesas were actually glaciers, as had long been expected. <ref name="Plaut, J. 2008">Plaut, J. et al.  2008. Radar Evidence for Ice in Lobate Debris Aprons in the Mid-Northern Latitudes of Mars. Lunar and Planetary Science XXXIX.  2290.pdf</ref> <ref>http://hirise.lpl.arizona.edu/PSP_009535_2240</ref>  Ice was found both in the southern and northern hemispheres. <ref>cite journal | last1 = Holt | first1 = J. | last2 = Safaeinili | first2 = A. | last3 = Plaut | first3 = J. | last4 = Head | first4 = J. | last5 = Phillips | first5 = R. | last6 = Seu | first6 = R. | last7 = Kempf | first7 = S. | last8 = Choudhary | first8 = P. | last9 = Young | first9 = D. | last10 = Putzig | first10 = N. | last11 = Biccari | first11 = D. | last12 = Gim | first12 = Y. | year = 2008 | title = Radar sounding evidence for buried glaciers in the southern mid-latitudes of Mars | url = | journal = Science | volume =  322| issue = | pages =  1235–1238| doi = 10.1126/science.1164246 | pmid=19023078|</ref> <ref>cite journal | last1 = Plaut | first1 = J. | last2 = Safaeinili | first2 = A. | last3 = Holt | first3 = J. | last4 = Phillips | first4 = R. | last5 = Head | first5 = J. | last6 = Seu | first6 = R. | last7 = Putzig | first7 = N. | last8 = Frigeri | first8 = A. | year = 2009 | title = Radar evidence for ice in lobate debris aprons in the midnorthern latitudes of Mars | url = | journal = Geophys. Res. Lett. | volume =  36| issue = | page =  | doi = 10.1029/2008GL036379 |</ref> <ref>Holt, J., et al.  2008.  Radar Sounding Evidence for Ice within Lobate Debris Aprons, near Hellas Basin, Mid-southern Latitudes of Mars. Lunar and Planetary Science XXXIX.  2441.pdf</ref>


<gallery class="center"  widths="380px" heights="360px">
[[Image:   Mars Reconnaissance Orbiter spacecraft model.png |thumb|200px|right|Artist view of Mars Reconnaissance Orbiter ]]
File:800px-Wideviewlda42n18e.jpg|Lobate debris apron (LDA) around a mesa  Radar proved that a LDA is mostly ice.
</gallery>

[[File:77699 2215contextldactx.jpg|600pxr|Wide and close views of LDA]]


                                 Wide and close views of LDA

==Lineated Valley Fill==

Another ice-rich feature is called lineated valley fill (LVF). <ref>Carr, M. 2006. The Surface of Mars.  Cambridge University Press. ISBN|978-0-521-87201-0</ref> <ref>Squyres, S.  1978.  Martian fretted terrain:  Flow of erosional debris.  Icarus: 34. 600-613.</ref> <ref>Levy,J. et al. 2007.  Lineated valley fill and lobate debris apron stratigraphy in Nilosyrtis Mensae, Mars: Evidence for phases of glacial modification of the dichotomy boundary. J. Geophys. Res. 112</ref> <ref> https://www.uahirise.org/ESP_026414_2205</ref>
It covers many of the wide, flat valley floors of fretted terrain.  Probably formed from the interaction of glaciers coming out of valleys and of mesas eroding, it has similar surface appearance of other supposed glaciers, including LDA.  It looks like the human brain.  Since the material covering ice is shaped into something resembling the human brain, it is named brain terrain.  Two types, open and closed have been identified.  The closed still holds an ice core.  Brain terrain starts to form when cracks occur on an ice-rich surface.  [[Sublimation]] along the cracks turns the cracks into small valleys.  Regions called Nilosyrtis Mensae, Protonilus Mensae and Deuteronilus Mensae display many examples of LVF.  The Ismenius Lacus quadrangle and Hellas quadrangle contain many valleys exhibiting lineated valley fill.<ref>Mellon, M.  1997.  Small-scale polygonal features on Mars:  Seasonal thermal contraction cracks in permafrost.  J. Geophysical Res: 102. 25,617-625,628.</ref> <ref>Levy, J. et al.  2009.  Concentric crater fill in Utopia Planitia:  History and interaction between glacial "brain terrain" and periglacial processes.  Icarus: 202.  462-476.</ref>  <ref name="Souness, C 2013">cite journal | author = Souness C., Hubbard B. | year = 2013 | title = An alternative interpretation of late Amazonian ice flow: Protonilus Mensae, Mars | url = | journal = Icarus | volume = 225 | issue = | pages = 495–505 | doi=10.1016/j.icarus.2013.03.030 |</ref> <ref name="Noach">cite journal |author1=Head, J.  |author2=D. Marchant  |lastauthoramp=yes| date = 2006 | title = Modification of the walls of a Noachian crater in northern Arabia Terra (24E, 39N) during mid-latitude Amazonian glacial epochs on Mars:  Nature and evolution of lobate debris aprons and their relationships to lineated valley fill and glacial systems | journal = Lunar Planet. Sci | volume =  37 | page =  Abstract # 1126</ref> <ref>cite journal | author = Kress, A., J. Head | date =  2008 | title =  Ring-mold craters in lineated valley fill and lobate debris aprons on Mars:  Evidence for subsurface glacial ice | journal = Geophys. Res. Lett. | volume = 35 | page = L23206–8 | doi=10.1029/2008gl035501|</ref> <ref>cite journal | author = Baker, D. | date = 2010 | title = Flow patterns of lobate debris aprons and lineated valley fill north of Ismeniae Fossae, Mars:  Evidence for extensive mid-latitude glaciation in the Late Amazonian | journal = Icarus | volume = 207 | pages = 186–209 | doi = 10.1016/j.icarus.2009.11.017 | last2 = Head | first2 = James W. | last3 = Marchant | first3 = David R. </ref>  <ref>cite journal |author1=Kress., A.  |author2=J. Head  |lastauthoramp=yes| date = 2009 | title = Ring-mould craters on lineated valley fill, lobate debris aprons, and concentric crater fill on Mars:  Implications for near-surface structure, composition, and age | journal = Lunar Planet. Sci | volume = 40 | page = abstract 1379</ref>


<gallery class="center"  widths="380px" heights="360px">
File:56544 2200lvfbrains.jpg|Wide view of Lineated Valley Fill  
File:56544 2200lvf.jpg|Close view of Lineated Valley Fill   The  location is the Ismenius Lacus quadrangle.
File:54527 2225brainsclosecolor.jpg|Close view of brain terrain   Brain terrain covers many types of Martian glaciers.
File:ESP 053642 2225brainslabeled.jpg|Closed cell brain terrain still contains a core of ice.  When the ice leaves it becomes open cell brain terrain.
</gallery>

==Concentric Crater Fill==

Concentric crater fill (CCF) is a third easily identifiable landscape that is covered with brain terrain and loaded with water.  Craters with CCF are shallow.  Even though they started out with a deep bowl shape, today they are full. We know how deep the crater was when formed because crater studies have found a relationship between the diameter of a crater and its original depth.  For example, in many parts of Mars the diameter of a crater is 10 times the depth.<ref>http://adsabs.harvard.edu/full/1993mppf.proc....1B</ref>  So if see that a crater is 10 km across, we know that it started out being 1 km deep.  These craters may be big, but they are shallow.   Scientists believe they are full of dust and ice.  As material moves down crater walls toward the center, concentric lines of brain terrain are created. <ref>Garvin, J. et al.  2002.  Lunar Planet. Sci:  33.  Abstract # 1255.</ref>
<ref>http://hiroc.lpl.arizona.edu/images/PSP/diafotizo.php?ID=PSP_111926_2185</ref>  <ref>Dickson, J., et al.  2009.  Kilometer-thick ice accumulation and glaciation in the northern mid-latitudes of Mars:  Evidence for crater-filling events in the Late Amazonian at the Phlegra Montes.  Earth and Planetary Science Letters.</ref> <ref>cite web|url=http://hirise.lpl.arizona.edu/PSP_001926_2185|title=HiRISE - Concentric Crater Fill in the Northern Plains (PSP_001926_2185)|author=|date=|website=hirise.lpl.arizona.edu</ref>  <ref>Levy, J. et al.  2009.  Concentric crater fill in Utopia Planitia:  History and interaction between glacial "brain terrain" and periglacial processes.  Icarus: 202. 462-476.</ref>


<gallery class="center"  widths="380px" heights="360px">
File:30707946 10212010896087124 5214252926280663040 nccf.jpg|Concentric  Crater Fill, as seen by CTX  This crater was bowl shaped when formed; now it is full of ice and dust .  
File:Ccffigurecaptioned.jpg| The depth of craters can be predicted based upon the observed diameter.  Many craters are almost full, instead of having bowl shape; consequently, it is believed that they have added ice, dust, and other debris since they were formed. 
</gallery>

==Source of Ice==

Multiple studies imply there is plenty of ice on Mars.  Ice is abundant from about 30 degrees latitude up to the poles. <ref name="HeadDistn">cite journal | last1 = Head | first1 = J. W. | display-authors = 1 | last2 = et al | year = 2006 | title = Extensive valley glacier deposits in the northern mid-latitudes of Mars: Evidence for Late Amazonian obliquity-driven climate change | url = | journal = Earth and Planetary Science Letters | volume = 241 | issue = 3| pages = 663–671 | doi=10.1016/j.epsl.2005.11.016 |</ref> <ref>Kieffer, H., et al. (eds).  1992.  Mars.  University of Arizona Press.  Tucson.  ISBN 0-8165-1257-4</ref>  How did it get there?  It is now widely believed that snow and ice-coated dust drops from the sky when the climate of Mars changes--as it frequently does. <ref>cite journal | last1 = Touma | first1 = J. | last2 = Wisdom | first2 = J. | year = 1993 | title = The Chaotic Obliquity of Mars | url = | journal = Science | volume = 259 | issue = | pages = 1294–1297 | doi=10.1126/science.259.5099.1294 | pmid=17732249|</ref> <ref name="ReferenceB">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 | url = | journal = Icarus | volume = 170 | issue = | pages = 343–364 | doi=10.1016/j.icarus.2004.04.005 |</ref>     Calculations reveal that the tilt of Mars drastically changes due to the lack of a large moon to stabilize it.<ref>https://www.uahirise.org/hipod/ESP_034132_1750</ref>   When the tilt changes, the climate changes.  At times, the ice in the polar deposits leaves and goes to mid-latitudes.<ref>http://hirise.lpl.arizona.edu/PSP_002917_2175</ref> <ref>Forget, F., et al.  2006.  Planet Mars Story of Another World.  Praxis Publishing, Chichester, UK.  ISBN|978-0-387-48925-4</ref> During this time, ice in the cap sublimates, and thick snow falls in mid-latitudes — the zones where concentric crater fill, lineated valley fill and lobate debris aprons are common.<ref>Carr, M.  2006.  The Surface of Mars.  Cambridge University Press.   ISBN|978-0-521-87201-0 </ref> <ref name="obliq">cite journal | author = Head, J. | date = 2006 | title = Extensive valley glacier deposits in the northern mid-latitudes of Mars:  Evidence for late Amazonian obliquity-driven climate change | journal = Earth Planet. Sci. Lett. | volume = 241 | pages = 663–671 |doi=10.1016/j.epsl.2005.11.016 | issue = 3–4| last2 = Marchant | first2 = D.R. | last3 = Agnew | first3 = M.C. | last4 = Fassett | first4 = C.I. | last5 = Kreslavsky | first5 = M.A. </ref> <ref>cite journal | author = Levy, J. | display-authors = etal | date = 2007 | title = Lineated valley fill and lobate debris apron stratigraphy in Nilosyrtis Mensae, Mars:  Evidence for phases of glacial modification of the dichotomy boundary | journal = J. Geophys. Res. | volume = 112 | doi=10.1029/2006je002852 |</ref> <ref>Levy, J., J. Head, D. Marchant, D. Kowalewski.  2008.  Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix landing site: Implications for substrate properties and climate-driven morphological evolution. Geophys. Res. Lett. 35. </ref>   It is deposited as something called latitude dependent mantle.  Over time, some ice disappears and leaves a covering lag deposit that prevents further loss of ice. <ref name="Mellon, M. 1995">cite journal | last1 = Mellon | first1 = M. | last2 = Jakosky | first2 = B. | year = 1995 | title = The distribution and behavior of Martian ground ice during past and present epochs | url = | journal = J. Geophys. Res. | volume = 100 | issue = | pages = 11781–11799 | doi=10.1029/95je01027 |</ref> <ref name="Mellon, M. 1995"/> <ref>cite journal | last1 = Schorghofer | first1 = N | year = 2007 | title = Dynamics of ice ages on Mars | url = | journal = Nature | volume = 449 | issue = | pages = 192–194 | doi=10.1038/nature06082 | pmid=17851518|</ref>     Also, dust and other debris collect on the surface.  Together, these coverings help to build up an ice-rich, long lasting smooth mantle that can eventually generate glaciers.  If it gets thick enough, the ice mass will be pulled downhill by gravity.  On Earth, glaciers often melt at the base.  The resulting water helps the glacier slide.  However, glaciers also move from internal movement of ice crystals sliding over each other.  It flows like a soft plastic.<ref> http://www.geography-site.co.uk/pages/physical/glaciers/origin.html</ref>   <ref>Earth Science.  2001.  Holt Science &Technology.  New York</ref>    This  plastic movement will not change the shape of the ground under the glacier; however, the glacier will still carry debris and make structures called moraine.


<gallery class="center"  widths="380px" heights="360px">
 46444 2225mantle.jpg|Latitude dependent mantle
File:ESP 028352 2245glacier.jpg|Glacier that has lost much of its ice, but has built moraines
File:Moraines52720 2250.jpg|Old Glacier with multiple moraines indicated with arrows   When the glacier retreated it stopped at times and left behind a moraine.  Material is still transported to the end (snout) of a glacier when it is not advancing.
</gallery>

Moraines are common on Mars. <ref>Milliken, R., J. Mustard, D. Goldsby.  2003.  Viscous flow features on the surface of Mars: Observations from high-resolution Mars Orbiter Camera (MOC) images. J. Geophys. Res. 108. </ref>   It is believed that most glaciers on Mars are “cold based” that is they do not melt.  Remember, under current conditions ice does not melt, rather it changes  directly to a gas in a process called [[sublimation]].  We do not know if any ice melted in the past.  We may understand the situation much better after we study data from the [[InSight Mission]] which landed on Mars at the end of November 2018.  InSight will measure the heat flow.  A combination of high heat flow and pressure from thick ice, may have generated sufficient heat to cause some melting.

After several unsuccessful attempts, NASA gave up trying to get heat flow measurements because of the nature of the soil.  The drill, called the mole, could not go deep enough.  It kept popping out.  Almost two years of trying different approaches did not work.  The team attempted to push down the mole with the scoop on the end of the lander’s robotic arm to prevent it from rebounding.  They tried to tamp down regolith around the hole.  They filled in the widening hole so the mole could gain more friction, but nothing worked.<ref>https://spacenews.com/nasa-ceases-efforts-to-deploy-mars-insight-heat-flow-probe</ref> <ref>https://www.jpl.nasa.gov/news/nasa-insights-mole-ends-its-journey-on-mars</ref>

[[File:PIA17358-MarsInSightLander-20140326.jpg|600pxr|Labeled drawing of InSight Lander]]

==Other Possible Glaciers==

Besides features that look like terrestrial glaciers, LDM, LVF, and CCF; there are other shapes that may be glaciers. <ref>Head, J. and D. Marchant.  2006.  Evidence for global-scale northern mid-latitude glaciation in the Amazonian period of Mars:  Debris-covered glacial and valley glacial deposits in the 30 - 50 N latitude band.  Lunar. Planet. Sci. 37.  Abstract 1127</ref> <ref>Head, J. and D. Marchant.  2006.  Modifications of the walls of a Noachian crater in Northern Arabia Terra (24 E, 39 N) during northern mid-latitude Amazonian glacial epochs on Mars:  Nature and evolution of Lobate Debris Aprons and their relationships to lineated valley fill and glacial systems.  Lunar. Planet. Sci. 37.  Abstract 1128</ref> <ref>Head, J., et al.  2006.  Extensive valley glacier deposits in the northern mid-latitudes of Mars:  Evidence for the late Amazonian obliquity-driven climate change.  Earth Planet. Sci. Lett. 241.  663-671</ref> <ref>Head, J., et al.  2006. Modification if the dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation.  Geophys. Res Lett.  33</ref> They appear as curved ridges and have been called various names by different researchers.  Some of the names are Viscus Flow Features (VFF), arcuate ridges, Glacial-like Flows (GLF), Glacier-like Forms (GLF), and Moraine-like Ridges (MLR). <ref> Milliken, R., et al.  2003.  Viscous flow features on the surface of Mars:  Observations from high-resolution Mars Orbiter Camera (MOC) images.  Journal of Geophysical Research:  108.  Doi:10.1029/2002JE002005</ref> <ref>Berman, D., et al.  2005.  The role of arcuate ridges and gullies in the degradation  of craters in the Newton Basin regions of Mars.  Icarus: 178, 465-486.</ref> <ref>cite journal
 | last1 = Arfstrom | first1 = J
 | last2 = Hartmann | first2 = W. | year = 2005
 | title = Martian flow features, moraine-like ridges, and gullies:  Terrestrial analogs and interrelationships
 | url = | journal = Icarus | volume = 174 | issue = | pages = 321–335
 | doi=10.1016/j.icarus.2004.05.026 | </ref>    <ref name="Hubbard B. 2011">cite journal
 | last1 = Hubbard | first1 = B.
 | last2 = Milliken | first2 = R.
 | last3 = Kargel | first3 = J.
 | last4 = Limaye | first4 = A.
 | last5 = Souness | first5 = C.
 | year = 2011 | title = Geomorphological characterisation and interpretation of a mid-latitude glacier-like form: Hellas Planitia, Mars
 | url = | journal = Icarus | volume = 211 | issue = | pages = 330–346
 | doi=10.1016/j.icarus.2010.10.021 |</ref> <ref name="Hubbard B. 2011"/> <ref>http://www.antarcticglaciers.org/glacial-geology/glaciers-mars/</ref>  Most lie in impact craters.  Gullies are associated with many of them.   These curved ridges may be created as snow and ice accumulate high on crater walls until gravity pulls them down.  As they slide down, they may push material into ridges.


<gallery class="center"  widths="380px" heights="360px">
File:Gullies and tongue-shaped glacier.jpg|Gullies and ridges that may be the remains of old glaciers  Glaciers may have dropped moraine debris or pushed floor material into ridges.
File:44410 2195glacier.jpg|Ridge downslope from a gully    This ridge in a crater may be created by a glacier.
</gallery>

==Glaciers on Volcanoes==

Most major Martian volcanoes display evidence of past glaciation. <ref name="HeadTropical">cite journal | last1 = Head | first1 = J. W. | display-authors = 1 | last2 = et al | year = 2005 | title = Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars | url = | journal = Nature | volume = 434 | issue = 7031| pages = 346–351 | doi=10.1038/nature03359 | pmid=15772652|</ref> <ref name="SheanPavonis">cite journal | last1 = Shean | first1 = David E. | title = Origin and evolution of a cold-based tropical mountain glacier on Mars: The Pavonis Mons fan-shaped deposit | journal=Journal of Geophysical Research | volume = 110 | date = 2005 | doi = 10.1029/2004JE002360 | </ref> <ref name="HeadMarchantArsia">cite journal | last1 = Head | first1 = James W. | last2 = Marchant | first2 = David R. | year = 2003 | title = Cold-based mountain glaciers on Mars: western Arsia Mons | url = | journal = Geology | volume = 31 | issue = 7| pages = 641–644 | doi=10.1130/0091-7613(2003)031<0641:cmgomw>2.0.co;2|</ref>
<ref name="Hauber, E. 2005">Cite journal|author=Hauber, E. |date=2005 |title=Discovery of a flank caldera and very young glacial activity at Hecates Tholus, Mars |journal=Nature |volume=434 |pages=356–61|pmid=15772654|issue=7031|doi=10.1038/nature03423 |last2=Van Gasselt |first2=Stephan |last3=Ivanov |first3=Boris |last4=Werner |first4=Stephanie |last5=Head |first5=James W. |last6=Neukum |first6=Gerhard |last7=Jaumann |first7=Ralf |last8=Greeley |first8=Ronald |last9=Mitchell |first9=Karl L. |last10=Muller |first10=Peter |last11=Co-Investigator Team |first11=The Hrsc </ref> <ref>Scanlon, K., J. Head, D. Marchant.  2015. REMNANT BURIED ICE IN THE ARSIA MONS FAN-SHAPED DEPOSIT, MARS.  46th Lunar and Planetary Science Conference.  2266.pdf</ref> 
<ref name="ReferenceA">cite journal | last1= Shean | first1= David E. | last2= Head | first2= James W. | last3= Fastook | first3= James L. | last4= Marchant | first4= David R. | title= Recent glaciation at high elevations on Arsia Mons, Mars: Implications for the formation and evolution of large tropical mountain glaciers| page= E03004 | date= 2007 | issue= E3 | volume= 112 | doi = 10.1029/2006JE002761 | journal= Journal of Geophysical Research | url=http://www.planetary.brown.edu/pdfs/3281.pdf | format = PDF | </ref> <ref name="Shean, D. 2005">Cite journal|author=Shean, D. |display-authors=etal |date=2005 |title=Origin and evolution of a cold-based mountain glacier on Mars: The Pavonis Mons fan-shaped deposit |journal=Journal of Geophysical Research |volume=110|issue=E5 |page=E05001 | doi = 10.1029/2004JE002360 |</ref> <ref name="Basilevsky, A. 2006">Cite journal|author=Basilevsky, A.  |date=2006 |title=Geological recent tectonic, volcanic and fluvial activity on the eastern flank of the Olympus Mons volcano, Mars |journal=Geophysical Research Letters |volume=33 |issue=13 |pages=13201, L13201 |doi=10.1029/2006GL026396 |last2=Werner |first2=S. C. |last3=Neukum |first3=G. |last4=Head |first4=J. W. |last5=Van Gasselt |first5=S. |last6=Gwinner |first6=K. |last7=Ivanov |first7=B. A. </ref> Scientists now believe that glaciers exist on many of the volcanoes in Tharsis, including Olympus Mons, Ascraeus Mons, and Pavonis Mons.<ref>https://www.scienceinschool.org/2014/issue28/mars_glaciers</ref> <ref>cite journal | last1=Shean | first1=David E. | title=Origin and evolution of cold-based tropical mountain glacier on Mars: the Pavonis Mons fan-shaped deposit | journal=Journal of Geophysical Research | volume=110 | year=2005 | doi= 10.1029/2004JE002360 |</ref> <ref>cite journal | last1=Fassett | first1=C | last2=Headiii | first2=J | title=Valley formation on martian volcanoes in the Hesperian: Evidence for melting of summit snowpack, caldera lake formation, drainage and erosion on Ceraunius Tholus | url=http://www.planetary.brown.edu/pdfs/3408.pdf | format=PDF | journal=Icarus | volume=189 | pages=118–135 | year=2007| doi = 10.1016/j.icarus.2006.12.021 |</ref>
<ref>cite journal | last1= Plaut | first1= Jeffrey J. | last2= Safaeinili | first2= Ali | last3= Holt | first3= John W. | last4= Phillips | first4= Roger J. | last5= Head | first5= James W. | last6= Seu | first6= Roberto | last7= Putzig | first7= Nathaniel E. | last8= Frigeri | first8= Alessandro | title= Radar Evidence for Ice in Lobate Debris Aprons in the Mid-Northern Latitudes of Mars | journal= Geophysical Research Letters | volume= 36 | issue= 2 | pages=  | year= 2009 | doi = 10.1029/2008GL036379 |url=http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2290.pdf | format=PDF |</ref> <ref>cite journal | title= Radar Sounding Evidence for Ice within Lobate Debris Aprons near Hellas Basin, Mid-Southern Latitudes of Mars | url=http://www.lpi.usra.edu/meetings/lpsc2008/pdf/2441.pdf | format=PDF | journal = Lunar and Planetary Science |volume=XXXIX | pages = 2441 |year=2008 |last1= Holt | first=J.W.| last2 = Safaeinili | first2 = A. | last3 = Plaut | first3 = J. J. | last4 = Young | first4 = D. A. | last5 = Head | first5 = J. W. | last6 = Phillips | first6 = R. J. | last7 = Campbell | first7 = B. A. | last8 = Carter | first8 = L. M. | last9 = Gim | first9 = Y. | last10 = Seu | first10 = R. | author11 = Sharad Team </ref  >Many large mountains on Earth also have glaciers.  It is cold on mountain tops.  Snow often falls heavily there; therefore, one would expect glaciers on Martian volcanoes.

==Vast Ice Sheets==

Besides smaller glaciers around mesas, in craters, and on mountains, Mars may have had giant ice sheets, twice the area of the state of Texas.<ref>cite journal | last1 = Scanlon | first1 = K. | display-authors = 1 | last2 = et al | year = 2018 | title =  | url = | journal = Icarus | volume = 299 | issue = | pages = 339–363| doi = 10.1016/j.icarus.2017.07.031</ref> <ref>Allen, C.  1979.  Volcano-ice interactions on Mars.  ''J. Geophys. Res.: Solid Earth (1978–2012)'', 84 (B14),  8048-8059.</ref> <ref>Howard, 1981</ref> <ref>cite journal | last1 = Kargel | first1 = J. | last2 = Strom | first2 = R. | year = 1992 | title = Ancient glaciation on mars | url = | journal = Geology | volume = 20 | issue = 1| pages = 3–7| doi = 10.1130/0091-7613(1992)020<0003:AGOM>2.3.CO;2 </ref> <ref>Head, J, S. Pratt.  2001.  Extensive Hesperian-aged south polar ice sheet on Mars: Evidence for massive melting and retreat, and lateral flow and pending of meltwater.  J. Geophys. Res.-Planet, 106 (E6), 12275-12299.</ref>  Some researchers have estimated that one ice sheet was nearly a mile thick.  Near the South Pole in the Dorsa Argentea Formation are tangles of ridges that resemble what is left from streams under glaciers.  These are called eskers.  In the same general area are shapes, now named Sisyphi Montes, that look like what is formed on Earth when volcanoes erupt under glaciers; they have steep walls and flat tops.<ref> Ghatan, G.J. and J.W. Head, III.  2002.  Candidate subglacial volcanoes in the south polar region of Mars: morphology, morphometry, and eruption conditions. J. Geophys. Res., 107(E7), 5048. (10.1029/2001JE001519.)</ref> <ref> Ghatan, G.J., J.W. Head, III and S. Pratt.   2003.  Cavi Angusti, Mars:  characterization and assessment of possible formation mechanisms.  J. Geophys. Res., 108(E5), 5045. (10.1029/2002JE001972.) </ref> <ref>Head, J., L. Wilson.  2007.   Heat Transfer in Volcano-Ice Interactions on Mars:  Synthesis of Environments and Implications for Processes and Landforms.  Annals of Glaciology.  45</ref>   These features are common in Iceland.  Earlier studies support the idea that glaciers on Mars may have been much thicker and more extensive in the past.  It appears in many places that LVF has dropped, probably because it has lost ice.<ref> Dickson, J., et al.  2009.  Kilometer-thick ice accumulation and glaciation in the northern mid-latitudes of Mars:  Evidence for crater-filling events in the Late Amazonian at the Phlegra Montes.  Earth and Planetary Letters.  Doi:10.1016/j.epsl.2009.08.031</ref> <ref> Levy, J., et al.  2007.  Lineated valley fill and lobate debris apron stratigraphy in Nilosyrtis Mensae, Mars:  Evidence for phases of glacial modification of the dichotomy boundary.  Journal of Geophysical Research:  112, E08004</ref> <ref>Head, J., et al.  2006.  Modification of the dichotomy boundary on Mars by Amazonian mi-latitude regional glaciation.  Geophysical Research Letters:  33, L08S03</ref> <ref> Dickson, J., et al.  2008.  Late Amazonian glaciation at the dichotomy boundary on Mars:  Evidence for glacial thickness maxima and multiple glacial phases.  Geology:  36, 411-414.</ref>

[[File:R0502109dorsaargentea.jpg|thumb|300px|left|Possible eskers indicated by arrows.  Eskers form under glaciers.]]

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

==See also==

* [[High Resolution Imaging Science Experiment (HiRISE)]]

* [[InSight Mission]]
* [[Martian features that are signs of water ice ]] 
* [[Periodic climate changes on Mars]]
* [[Tharsis]]
* [[Water]]

== External links ==

*Baker, D. and L. Carter.  2019.  Probing supraglacial debris on Mars 1: Sources, thickness, and stratigraphy.  Icarus.  Volume 319.   Pages 745-769

*Jawin, E.,et al.  2018.  Transient post-glacial processes on Mars: Geomorphologic evidence for a paraglacial period.  Icarus.  Volume 309.  Pages 187-206
 
*Head, J., et al.  2023.  GEOLOGICAL AND CLIMATE HISTORY OF MARS: IDENTIFICATION OF POTENTIAL WARM AND
WET CLIMATE ‘FALSE POSITIVES’.  54th Lunar and Planetary Science Conference 2023 (LPI Contrib. No. 2806).  1731.pdf

* [https://www.youtube.com/watch?v=D-SCOHj8u-A  Water on Mars - James Secosky - 2021 Mars Society Virtual Convention -- Tells where water was and where ice is today on Mars (34 minutes)]

*[https://www.youtube.com/watch?v=RYG-HLr33CM Jim Secosky - Martian Geology - 16th Annual International Mars Society Convention]

* [https://www.youtube.com/watch?v=_sUUKcZaTgA   Martian Ice - Jim Secosky - 16th Annual International Mars Society Convention]

* [https://www.youtube.com/watch?v=z6B742f8yPs  Mars Bunker: Martian Ice Revealed]
* [https://www.youtube.com/watch?v=m2ERsEXAq_s Jeffrey Plaut - Subsurface Ice - 21st Annual International Mars Society Convention]
* https://www.youtube.com/watch?v=kpnTh3qlObk[T. Gordon Wasilewski - Water on Mars - 20th Annual International Mars Society Convention]  Describes how to get water from ice in the ground
* High resolution [https://www.flickr.com/photos/seandoran/30604739258/ flyover video] by Seán Doran of a glacier in Protonilus Mensae, based on NASA [https://www.uahirise.org/ESP_018857_2225 digital terrain model]; see [https://www.flickr.com/photos/seandoran/albums/72157677941945560 album] for more
* [https://www.youtube.com/watch?v=j8P9pE8CYgI Glaciers on Mars?]

* [https://www.sciencedirect.com/science/article/pii/S0019103520305121#f0010  Gallagher. c.  et al.  In press 2020.  Landforms indicative of regional warm based glaciation, Phlegra Montes, Mars.  Icarus ]


[[Category: Geologic Processes]]