Difference between revisions of "Ismenius Lacus quadrangle"

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This quadrangle has some of the most mysterious-looking landscapes on the planet.  It truly looks like another world here.  Strong evidence of a past ocean on Mars exists in this region and is described below.  The Ismenius Lacus quadrangle contains regions called Deuteronilus Mensae and Protonilus Mensae, two places that are of special interest to scientists.  They contain abundant evidence of present and past glacial activity.  They also have a landscape unique to Mars, called Fretted terrain.  The largest crater in the area is Lyot Crater, which contains channels probably carved by liquid water.<ref>Carter | first1 = J. | last2 = Poulet | first2 = F. | last3 = Bibring | first3 = J.-P. | last4 = Murchie | first4 = S. | year = 2010 | title = Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars | url = | journal = Science | volume = 328 | issue = 5986| pages = 1682–1686 | </ref>
 
This quadrangle has some of the most mysterious-looking landscapes on the planet.  It truly looks like another world here.  Strong evidence of a past ocean on Mars exists in this region and is described below.  The Ismenius Lacus quadrangle contains regions called Deuteronilus Mensae and Protonilus Mensae, two places that are of special interest to scientists.  They contain abundant evidence of present and past glacial activity.  They also have a landscape unique to Mars, called Fretted terrain.  The largest crater in the area is Lyot Crater, which contains channels probably carved by liquid water.<ref>Carter | first1 = J. | last2 = Poulet | first2 = F. | last3 = Bibring | first3 = J.-P. | last4 = Murchie | first4 = S. | year = 2010 | title = Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars | url = | journal = Science | volume = 328 | issue = 5986| pages = 1682–1686 | </ref>
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The Ismenius Lacus quadrangle  is located in the northern hemisphere and covers 30° to 65° north latitude and 300° to 360° west longitude (60° to 0° east longitude). The southern and northern borders of the Ismenius Lacus quadrangle are approximately 3065 km (1,905 mi) and 1500 km wide (930 mi)  respectively. The north-to-south distance is about 2050 km (1,270 mi) (a bit less than the length of Greenland).<ref>Distances calculated using NASA World Wind measuring tool. http://worldwind.arc.nasa.gov/.</ref> The Ismenius Lacus quadrangle contains parts of regions named Acidalia Planitia, Arabia Terra, Vastitas Borealis, and Terra Sabaea.<ref>http://planetarynames.wr.usgs.gov/SearchResults?target=MARS&featureType=Terra,%20terrae</ref>
 
The Ismenius Lacus quadrangle  is located in the northern hemisphere and covers 30° to 65° north latitude and 300° to 360° west longitude (60° to 0° east longitude). The southern and northern borders of the Ismenius Lacus quadrangle are approximately 3065 km (1,905 mi) and 1500 km wide (930 mi)  respectively. The north-to-south distance is about 2050 km (1,270 mi) (a bit less than the length of Greenland).<ref>Distances calculated using NASA World Wind measuring tool. http://worldwind.arc.nasa.gov/.</ref> The Ismenius Lacus quadrangle contains parts of regions named Acidalia Planitia, Arabia Terra, Vastitas Borealis, and Terra Sabaea.<ref>http://planetarynames.wr.usgs.gov/SearchResults?target=MARS&featureType=Terra,%20terrae</ref>
  
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Ismenius Lacus is the name of a classical albedo feature located at 40° N and 30° E on Mars. Like most names for Martian places, Ismenius comes from old myths and stories.  The term is Latin for Ismenian Lake, and refers to the Ismenian Spring near Thebes in Greece where Cadmus slew the guardian dragon. Cadmus was the legendary founder of Thebes, and had come to the spring to fetch water. The name was approved by the International Astronomical Union (IAU) in 1958.<ref>USGS Gazetteer of Planetary Nomenclature. Mars. http://planetarynames.wr.usgs.gov/.</ref>  All names suggested for astronomical features have to eventually approved by the International Astronomical Union (IAU).
 
Ismenius Lacus is the name of a classical albedo feature located at 40° N and 30° E on Mars. Like most names for Martian places, Ismenius comes from old myths and stories.  The term is Latin for Ismenian Lake, and refers to the Ismenian Spring near Thebes in Greece where Cadmus slew the guardian dragon. Cadmus was the legendary founder of Thebes, and had come to the spring to fetch water. The name was approved by the International Astronomical Union (IAU) in 1958.<ref>USGS Gazetteer of Planetary Nomenclature. Mars. http://planetarynames.wr.usgs.gov/.</ref>  All names suggested for astronomical features have to eventually approved by the International Astronomical Union (IAU).
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Some important areas in this quadrangle derive from the names of canals that some early astronomers saw in this broad area.  One such large canal they called Nilus.  Since 1881–1882 it was split into other canals, some were called Nilosyrtis, Protonilus (first Nile),and Deuteronilus (second Nile).<ref>Blunck, J.  1982.  Mars and its Satellites.  Exposition Press.  Smithtown, N.Y.</ref>
 
Some important areas in this quadrangle derive from the names of canals that some early astronomers saw in this broad area.  One such large canal they called Nilus.  Since 1881–1882 it was split into other canals, some were called Nilosyrtis, Protonilus (first Nile),and Deuteronilus (second Nile).<ref>Blunck, J.  1982.  Mars and its Satellites.  Exposition Press.  Smithtown, N.Y.</ref>
  
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[[File:ESP 054857 2270grooves.jpg|600pxr|Channels that may have been made by the backwash of tsunamis in an ocean  Image is from HiRISE under the [[HiWish program]]]]
 
[[File:ESP 054857 2270grooves.jpg|600pxr|Channels that may have been made by the backwash of tsunamis in an ocean  Image is from HiRISE under the [[HiWish program]]]]
  
Channels made by the backwash from tsunamis, tsunamis were probably caused by asteroids striking the ocean.  Image is from HiRISE under the [[HiWish program]]
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Channels made by the backwash from tsunamis, tsunamis were probably caused by asteroids striking an ocean.  Image is from HiRISE under the [[HiWish program]]
  
Many researchers have suggested that Mars once had a great ocean in the north.<ref>Parker | first1 = T. J. | last2 = Gorsline | first2 = D. S. | last3 = Saunders | first3 = R. S. | last4 = Pieri | first4 = D. C. | last5 = Schneeberger | first5 = D. M. | year = 1993 | title = Coastal geomorphology of the Martian northern plains | url = | journal = J. Geophys. Res. | volume = 98 | issue = E6| pages = 11061–11078 | doi=10.1029/93je00618 |</ref> <ref>Fairén | first1 = A. G. |display-authors=etal | year = 2003 | title = Episodic flood inundations of the northern plains of Mars | url = http://eprints.ucm.es/10431/1/9-Marte_3.pdf| journal = Icarus | volume = 165 | issue = 1| pages = 53–67 | </ref> <ref> Head | first1 = J. W. |display-authors=etal | year = 1999 | title = Possible ancient oceans on Mars: Evidence from Mars Orbiter Laser Altimeter data | url = | journal = Science | volume = 286 | issue = 5447| pages = 2134–2137 | doi=10.1126/science.286.5447.2134| pmid = 10591640 |</ref> <ref>Parker, T. J., Saunders, R. S. & Schneeberger, D. M. Transitional morphology in west Deuteronilus Mensae, Mars: Implications for modification of the lowland/upland boundary" ''Icarus'' 1989; 82, 111–145</ref> <ref>Carr | first1 = M. H. | last2 = Head | first2 = J. W. | year = 2003 | title = Oceans on Mars: An assessment of the observational evidence and possible fate | url = | journal = J. Geophys. Res. | volume = 108 | issue = E5| page = 5042 |</ref> <ref>Kreslavsky | first1 = M. A. | last2 = Head | first2 = J. W. | year = 2002| title = Fate of outflow channel effluent in the northern lowlands of Mars: The Vastitas Borealis Formation as a sublimation residue from frozen ponded bodies of water | url = | journal = J. Geophys. Res. | volume = 107 | issue = E12| page = 5121 |</ref> <ref>Clifford, S. M. & Parker, T. J. The evolution of the martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains" ''Icarus'' 2001; 154, 40–79</ref> Much evidence for this ocean has been gathered over several decades.  New evidence was published in May 2016.  A large team of scientists described how some of the surface in Ismenius Lacus quadrangle was altered by two tsunamis.  The tsunamis were caused by asteroids striking the ocean.  Both were thought to have been strong enough to create 30 km diameter craters.  The first tsunami picked up and carried boulders the size of cars or small houses.  The backwash from the wave formed channels by rearranging the boulders.  The second came in when the ocean was 300 m lower.  The second carried a great deal of ice which was dropped in valleys.  Calculations show that the average height of the waves would have been 50 m, but the heights would vary from 10 m to 120 m. So, some large waves would have gone over a 36 story building.<ref>https://www.convertunits.com/from/metre/to/story</ref>  Numerical simulations show that in this particular part of the ocean two 30 km in diameter would form every 30 million years.  The implication here is that a great northern ocean may have existed for millions of years.  One argument against an ocean has been the lack of shoreline features.  These features may have been washed away by these tsunami events.  The parts of Mars studied in this research are Chryse Planitia and northwestern Arabia Terra.  These tsunamis affected some surfaces in the Ismenius Lacus quadrangle and in the [[Mare Acidalium quadrangle]].<ref>Ancient Tsunami Evidence on Mars Reveals Life Potential |date=May 20, 2016 |url=http://astrobiology.com/2016/05/ancient-tsunami-evidence-on-mars-reveals-life-potential.html</ref> <ref>Rodriguez | first1 = J. |display-authors=etal | year = 2016 | title = Tsunami waves extensively resurfaced the shorelines of an early Martian ocean | url = | journal = Scientific Reports | volume = 6 | issue = | page = 25106 | doi=10.1038/srep25106| pmid = 27196957 | pmc = 4872529 |</ref> <ref>| doi=10.1038/srep25106| pmid=27196957| pmc=4872529| title=Tsunami waves extensively resurfaced the shorelines of an early Martian ocean| journal=Scientific Reports| volume=6| pages=25106| year=2016| last1=Rodriguez| first1=J. Alexis P.| last2=Fairén| first2=Alberto G.| last3=Tanaka| first3=Kenneth L.| last4=Zarroca| first4=Mario| last5=Linares| first5=Rogelio| last6=Platz| first6=Thomas| last7=Komatsu| first7=Goro| last8=Miyamoto| first8=Hideaki| last9=Kargel| first9=Jeffrey S.| last10=Yan| first10=Jianguo| last11=Gulick| first11=Virginia| last12=Higuchi| first12=Kana| last13=Baker| first13=Victor R.| last14=Glines| first14=Natalie</ref> <ref>Cornell University. "Ancient tsunami evidence on Mars reveals life potential." ScienceDaily. ScienceDaily, 19 May 2016. https://www.sciencedaily.com/releases/2016/05/160519101756.htm.</ref>
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Many researchers have suggested that Mars once had a great ocean in the north.<ref>Parker | first1 = T. J. | last2 = Gorsline | first2 = D. S. | last3 = Saunders | first3 = R. S. | last4 = Pieri | first4 = D. C. | last5 = Schneeberger | first5 = D. M. | year = 1993 | title = Coastal geomorphology of the Martian northern plains | url = | journal = J. Geophys. Res. | volume = 98 | issue = E6| pages = 11061–11078 | doi=10.1029/93je00618 |</ref> <ref>Fairén | first1 = A. G. |display-authors=etal | year = 2003 | title = Episodic flood inundations of the northern plains of Mars | url = http://eprints.ucm.es/10431/1/9-Marte_3.pdf| journal = Icarus | volume = 165 | issue = 1| pages = 53–67 | </ref> <ref> Head | first1 = J. W. |display-authors=etal | year = 1999 | title = Possible ancient oceans on Mars: Evidence from Mars Orbiter Laser Altimeter data | url = | journal = Science | volume = 286 | issue = 5447| pages = 2134–2137 | doi=10.1126/science.286.5447.2134| pmid = 10591640 |</ref> <ref>Parker, T. J., Saunders, R. S. & Schneeberger, D. M. Transitional morphology in west Deuteronilus Mensae, Mars: Implications for modification of the lowland/upland boundary" ''Icarus'' 1989; 82, 111–145</ref> <ref>Carr | first1 = M. H. | last2 = Head | first2 = J. W. | year = 2003 | title = Oceans on Mars: An assessment of the observational evidence and possible fate | url = | journal = J. Geophys. Res. | volume = 108 | issue = E5| page = 5042 |</ref> <ref>Kreslavsky | first1 = M. A. | last2 = Head | first2 = J. W. | year = 2002| title = Fate of outflow channel effluent in the northern lowlands of Mars: The Vastitas Borealis Formation as a sublimation residue from frozen ponded bodies of water | url = | journal = J. Geophys. Res. | volume = 107 | issue = E12| page = 5121 |</ref> <ref>Clifford, S. M. & Parker, T. J. The evolution of the martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains" ''Icarus'' 2001; 154, 40–79</ref> Much evidence for this ocean has been gathered over several decades.  New evidence was published in May 2016.  A large team of scientists described how some of the surface in Ismenius Lacus quadrangle was altered by two tsunamis.  The tsunamis were caused by asteroids striking the ocean.  Both were thought to have been strong enough to create 30 km diameter craters.  The first tsunami picked up and carried boulders the size of cars or small houses.  The backwash from the wave formed channels by rearranging the boulders.  The second came in when the ocean was 300 m lower.  The second carried a great deal of ice which was dropped in valleys.  Calculations show that the average height of the waves would have been 50 m, but the heights would vary from 10 to 120 meters.   So, some large waves would have gone over a 36 story building.<ref>https://www.convertunits.com/from/metre/to/story</ref>  Numerical simulations show that in this particular part of the ocean two 30 km in diameter would form every 30 million years.  The implication here is that a great northern ocean may have existed for millions of years.  One argument against an ocean has been the lack of shoreline features.  These features may have been washed away by these tsunami events.  The parts of Mars studied in this research are Chryse Planitia and northwestern Arabia Terra.  These tsunamis affected some surfaces in the Ismenius Lacus quadrangle and in the [[Mare Acidalium quadrangle]].<ref>Ancient Tsunami Evidence on Mars Reveals Life Potential |date=May 20, 2016 |url=http://astrobiology.com/2016/05/ancient-tsunami-evidence-on-mars-reveals-life-potential.html</ref> <ref>Rodriguez | first1 = J. |display-authors=etal | year = 2016 | title = Tsunami waves extensively resurfaced the shorelines of an early Martian ocean | url = | journal = Scientific Reports | volume = 6 | issue = | page = 25106 | doi=10.1038/srep25106| pmid = 27196957 | pmc = 4872529 |</ref> <ref>| doi=10.1038/srep25106| pmid=27196957| pmc=4872529| title=Tsunami waves extensively resurfaced the shorelines of an early Martian ocean| journal=Scientific Reports| volume=6| pages=25106| year=2016| last1=Rodriguez| first1=J. Alexis P.| last2=Fairén| first2=Alberto G.| last3=Tanaka| first3=Kenneth L.| last4=Zarroca| first4=Mario| last5=Linares| first5=Rogelio| last6=Platz| first6=Thomas| last7=Komatsu| first7=Goro| last8=Miyamoto| first8=Hideaki| last9=Kargel| first9=Jeffrey S.| last10=Yan| first10=Jianguo| last11=Gulick| first11=Virginia| last12=Higuchi| first12=Kana| last13=Baker| first13=Victor R.| last14=Glines| first14=Natalie</ref> <ref>Cornell University. "Ancient tsunami evidence on Mars reveals life potential." ScienceDaily. ScienceDaily, 19 May 2016. https://www.sciencedaily.com/releases/2016/05/160519101756.htm.</ref>
  
  
 
<gallery class="center"  widths="380px" heights="360px">
 
<gallery class="center"  widths="380px" heights="360px">
  
ESP 028537 2270tsunamischannels.jpg|Channels made by the backwash from tsunamis, tsunamis were probably caused by asteroids striking the ocean.
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ESP 028537 2270tsunamischannels.jpg|Channels made by the backwash from tsunamis, Tsunamis were probably caused by asteroids striking the ocean.
  
 
File:ESP 055714 2270tsunamibackwash.jpg|Possible backwash channels that may have been created by a tsunami, as seen by HiRISE under HiWish program
 
File:ESP 055714 2270tsunamibackwash.jpg|Possible backwash channels that may have been created by a tsunami, as seen by HiRISE under HiWish program
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</gallery>
 
</gallery>
  
Some places (like below) display a smaller channel within a larger, wider channel or valley.  When this occurs it means water went through the region at least two times in the past.  This implies that water was not here once for just a short period of time.
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Some places (like below) display a smaller channel within a larger, wider channel or valley.  When this occurs it means water went through the region at least two times in the past.  This implies that water was not just here once for a short period of time.
  
 
<gallery class="center"  widths="380px" heights="360px">
 
<gallery class="center"  widths="380px" heights="360px">
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File:ESP 057627 2175channelssapping.jpg|Channels  The ends of the channels have shapes that suggest they were formed by the process ofsapping.
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File:ESP 057627 2175channelssapping.jpg|Channels  The ends of the channels have shapes that suggest they were formed by the process of sapping.
 
File:ESP 057139 2140channels.jpg|Channels  These channels are in the ejecta of a crater; hence, they may have formed from warm ejecta melting ground ice.
 
File:ESP 057139 2140channels.jpg|Channels  These channels are in the ejecta of a crater; hence, they may have formed from warm ejecta melting ground ice.
  
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The vast northern plains of Mars are generally flat and smooth with few craters.  However, a few large craters do stand out.  The giant impact crater, Lyot, is easy to see in the northern part of Ismenius Lacus.  There are only a very few craters along the far northern latitudes.<ref>U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991</ref>  Lyot Crater is the deepest point in Mars's northern hemisphere.<ref>http://space.com/scienceastronomy/090514--mars-rivers.html</ref>  One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and Dust Devil Tracks.  Dust devils, which resemble miniature tornados, create tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. It does not take too much fine dust to cover those tracks--experiments in Earth laboratories demonstrate that only a few 10's of microns of dust will do the trick.  Note on units: a micron is an older name for micrometre or micrometer.  The width of a single human hair ranges from approximately 20 to 200 microns (μm); hence, the dust that can cover dust devil tracks may only be the thickness of a human hair.<ref>https://en.wikipedia.org/wiki/Micrometre</ref>  Light-toned materials are an important find because they are widely believed to contain minerals formed in water. Research, published in June 2010, described evidence for liquid water in Lyot crater in the past.
 
The vast northern plains of Mars are generally flat and smooth with few craters.  However, a few large craters do stand out.  The giant impact crater, Lyot, is easy to see in the northern part of Ismenius Lacus.  There are only a very few craters along the far northern latitudes.<ref>U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991</ref>  Lyot Crater is the deepest point in Mars's northern hemisphere.<ref>http://space.com/scienceastronomy/090514--mars-rivers.html</ref>  One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and Dust Devil Tracks.  Dust devils, which resemble miniature tornados, create tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. It does not take too much fine dust to cover those tracks--experiments in Earth laboratories demonstrate that only a few 10's of microns of dust will do the trick.  Note on units: a micron is an older name for micrometre or micrometer.  The width of a single human hair ranges from approximately 20 to 200 microns (μm); hence, the dust that can cover dust devil tracks may only be the thickness of a human hair.<ref>https://en.wikipedia.org/wiki/Micrometre</ref>  Light-toned materials are an important find because they are widely believed to contain minerals formed in water. Research, published in June 2010, described evidence for liquid water in Lyot crater in the past.
  
Many channels have been found near Lyot Crater.  Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick.  Calculations suggest that the ejecta would have had a temperature of at least 250 degrees Fahrenheit.  The valleys seem to start from beneath the ejecta near the outer edge of the ejecta.  The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean, channels in Lyot came after we had thought that Mars had dried up.  So Mars had flowing water later then we believed.<ref>doi=10.1002/2017GL073821 | volume=44 | issue=11 | title=Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation | journal=Geophysical Research Letters | pages=5336–5344 | last1 = Weiss | first1 = David K.| </ref> <ref>Weiss, D., et al.  2017.  Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation.  Geophysical Research Letters:  44, doi:10.1002/2017GL073821.</ref> <ref>http://spaceref.com/mars/hot-rocks-led-to-relatively-recent-water-carved-valleys-on-mars.html</ref>
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Many channels have been found near Lyot Crater.  Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick.  Calculations suggest that the ejecta would have had a temperature of at least 250 degrees Fahrenheit.  The valleys seem to start from beneath the ejecta near the outer edge of the ejecta.  The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean; channels in Lyot came after we had thought that Mars had dried up.  So Mars had flowing water later then we believed.<ref>doi=10.1002/2017GL073821 | volume=44 | issue=11 | title=Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation | journal=Geophysical Research Letters | pages=5336–5344 | last1 = Weiss | first1 = David K.| </ref> <ref>Weiss, D., et al.  2017.  Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation.  Geophysical Research Letters:  44, doi:10.1002/2017GL073821.</ref> <ref>http://spaceref.com/mars/hot-rocks-led-to-relatively-recent-water-carved-valleys-on-mars.html</ref>
  
 
[[File: ESP 045389 2295lyotchannels.jpg|600pxr|Wide view of channels in Lyot Crater, as seen by HiRISE under [[HiWish program]]]]
 
[[File: ESP 045389 2295lyotchannels.jpg|600pxr|Wide view of channels in Lyot Crater, as seen by HiRISE under [[HiWish program]]]]
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== Fretted terrain ==
 
== Fretted terrain ==
  
The Ismenius Lacus quadrangle contains several interesting features such as fretted terrain, parts of which are found in Deuteronilus Mensae and Protonilus Mensae.  Fretted terrain contains smooth, flat lowlands along with steep cliffs.  The scarps or cliffs are usually 1 to 2 km high.  Channels in the area have wide, flat floors and steep walls.  Many buttes and mesas are present.  In fretted terrain the land seems to transition from narrow straight valleys to isolated mesas.<ref>Sharp, R.  1973.  Mars Fretted and chaotic terrains.  J. Geophys. Res.:  78.  4073–4083</ref> Most of the mesas are surrounded by forms that have been called a variety of names: circum-mesa aprons, debris aprons, rock glaciers, and lobate debris apron (LDA)s.  The flat floors here often display many lines or lineations that scientists call lineated valley fill (LVF).  These are cause by glacier-like flow.  <ref>http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1053.pdf</ref> At first they appeared to resemble rock glaciers on Earth. But scientists could not be sure. Even after the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) took a variety of pictures of fretted terrain, experts could not tell for sure if material was moving or flowing as it would in an ice-rich deposit (glacier).  Eventually, proof of their true nature was discovered by radar studies with the [[Mars Reconnaissance Orbiter]] showed that they contain pure water ice covered with a thin layer of rocks that insulated the ice.<ref>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>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 = https://semanticscholar.org/paper/f6b94761e6a276ce6894374ae9bea88fdc3e5e19| journal = Geophys. Res. Lett. | volume =  36| issue = 2| pages = n/a |</ref>
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The Ismenius Lacus quadrangle contains several interesting features such as fretted terrain, parts of which are found in Deuteronilus Mensae and Protonilus Mensae.  Fretted terrain contains smooth, flat lowlands along with steep cliffs.  The scarps or cliffs are usually 1 to 2 km high.  Channels in the area have wide, flat floors and steep walls.  Many buttes and mesas are present.  In fretted terrain the land seems to transition from narrow straight valleys to isolated mesas.<ref>Sharp, R.  1973.  Mars Fretted and chaotic terrains.  J. Geophys. Res.:  78.  4073–4083</ref> Most of the mesas are surrounded by forms that have been called a variety of names: circum-mesa aprons, debris aprons, rock glaciers, and lobate debris apron (LDA)s.  The flat floors here often display many lines or lineations that scientists call lineated valley fill (LVF).  These are caused by glacier-like flow.  <ref>http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1053.pdf</ref> At first they appeared to resemble rock glaciers on Earth. But scientists could not be sure. Even after the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) took a variety of pictures of fretted terrain, experts could not tell for sure if material was moving or flowing as it would in an ice-rich deposit (glacier).  Eventually, proof of their true nature was discovered by radar studies with the [[Mars Reconnaissance Orbiter]] showed that they contain pure water ice covered with a thin layer of rocks that insulated the ice.<ref>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>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 = https://semanticscholar.org/paper/f6b94761e6a276ce6894374ae9bea88fdc3e5e19| journal = Geophys. Res. Lett. | volume =  36| issue = 2| pages = n/a |</ref>
  
 
<gallery class="center"  widths="380px" heights="360px">
 
<gallery class="center"  widths="380px" heights="360px">
  
Image:Fretted terrain of Ismenius Lacus taken with MGS.JPG|Fretted terrain of Ismenius Lacus showing flat floored valleys and cliffs.  Photo taken with Mars Orbiter Camera (MOC)on the [[Mars Global Surveyor]], under the MOC Public Targeting Program.  The white rectangle indicates the position of a high resolution image.
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Image:Fretted terrain of Ismenius Lacus taken with MGS.JPG|Fretted terrain of Ismenius Lacus showing flat floored valleys and cliffs.  Photo taken with Mars Orbiter Camera (MOC) on the [[Mars Global Surveyor]], under the MOC Public Targeting Program.  The white rectangle indicates the position of a high resolution image.
  
 
Image:Steep cliff in Ismenius Lacus taken with MGS.JPG|Enlargement of the photo on the left showing cliff.  Photo taken with high-resolution camera of Mars Global Surveyor (MGS), under the MOC Public Targeting Program.
 
Image:Steep cliff in Ismenius Lacus taken with MGS.JPG|Enlargement of the photo on the left showing cliff.  Photo taken with high-resolution camera of Mars Global Surveyor (MGS), under the MOC Public Targeting Program.
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Image:Evidence of Glaciers in Fretted terrain.JPG|The arrow in the left picture points to a possibly valley carved by a glacier.  The image on the right shows the valley greatly enlarged in a Mars Global Surveyor image.
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Image:Evidence of Glaciers in Fretted terrain.JPG|The arrow in the left picture points to a possibly valley carved by a glacier.  The image on the right shows the same valley greatly enlarged in a Mars Global Surveyor image.
  
 
ESP 050176 2245glacier.jpg|Glacier moving out of valley, as seen by HiRISE under HiWish program
 
ESP 050176 2245glacier.jpg|Glacier moving out of valley, as seen by HiRISE under HiWish program
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ESP 028339 2245headarticle.jpg|Well developed ribbed upper plains material.  These start with small cracks that expand as ice sublimates from the surfaces of the crack.   
 
ESP 028339 2245headarticle.jpg|Well developed ribbed upper plains material.  These start with small cracks that expand as ice sublimates from the surfaces of the crack.   
  
ESP 042765 2245cracks.jpg|Small and large cracks The small cracks to the left will enlarge to become much larger dues to sublimation of ground ice.  A crack exposes more surface area, hence greatly increases sublimation in the thin Martian air.
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ESP 042765 2245cracks.jpg|Small and large cracks The small cracks to the left will enlarge to become much larger due to sublimation of ground ice.  A crack exposes more surface area, hence greatly increases sublimation in the thin Martian air.
  
 
42765 2245close.jpg|Close-up of canyons from previous image
 
42765 2245close.jpg|Close-up of canyons from previous image
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Sand is common on Mars due to the old age of the surface that has allowed rocks to erode into sand. Dunes on Mars have been observed to move many meters.<ref>https://www.youtube.com/watch?v=ur_TeOs3S64</ref> <ref>https://uanews.arizona.edu/story/the-flowing-sands-of-mars</ref>
 
Sand is common on Mars due to the old age of the surface that has allowed rocks to erode into sand. Dunes on Mars have been observed to move many meters.<ref>https://www.youtube.com/watch?v=ur_TeOs3S64</ref> <ref>https://uanews.arizona.edu/story/the-flowing-sands-of-mars</ref>
 
In this process, sand moves up the windward side and then falls down the leeward side of the dune, thus caused the dune to go toward the leeward side (or slip face).<ref>Namowitz, S., Stone, D.  1975.  earth science the world we live in.  American Book Company.  New York.</ref>
 
In this process, sand moves up the windward side and then falls down the leeward side of the dune, thus caused the dune to go toward the leeward side (or slip face).<ref>Namowitz, S., Stone, D.  1975.  earth science the world we live in.  American Book Company.  New York.</ref>
When images are enlarged, some dunes on Mars display ripples on their surfaces.<ref>https://www.jpl.nasa.gov/news/news.php?feature=6551</ref>  These are caused by sand grains rolling and bouncing up the windward surface of a dune.  The bouncing grains tend to land on the windward side of each ripple.  The grains do not bounce very high so it does not take much to stop them.
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When images are enlarged, some dunes on Mars display ripples on their surfaces.<ref>https://www.jpl.nasa.gov/news/news.php?feature=6551</ref>   
  
 
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==Volcanoes under ice==
 
==Volcanoes under ice==
  
There is evidence that volcanoes sometimes erupt under ice, as they do on Earth at times.  What seems to happen it that much ice melts, the water escapes, and then the surface cracks and collapses.<ref>Smellie, J., B. Edwards.  2016.  Glaciovolcanism on Earth and Mars.  Cambridge University Press.</ref>  These exhibit concentric fractures and large pieces of ground that seemed to have been pulled apart.  Sites like this may have recently had held liquid water, hence they may be fruitful places to search for evidence of life.<ref>Levy, J. 2017">Levy, J., et al.  2017.  Candidate volcanic and impact-induced ice depressions on Mars.  Icarus:  285, 185–194.</ref> <ref>University of Texas at Austin. "A funnel on Mars could be a place to look for life." ScienceDaily. ScienceDaily, 10 November 2016. <https://www.sciencedaily.com/releases/2016/11/161110125408.htm>.</ref>
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There is evidence that volcanoes sometimes erupt under ice, as they do on Earth at times.  What seems to happen is that much ice melts, the water escapes, and then the surface cracks and collapses.<ref>Smellie, J., B. Edwards.  2016.  Glaciovolcanism on Earth and Mars.  Cambridge University Press.</ref>  These exhibit concentric fractures and large pieces of ground that seemed to have been pulled apart.  Sites like this may have recently had held liquid water, hence they may be fruitful places to search for evidence of life.<ref>Levy, J. 2017">Levy, J., et al.  2017.  Candidate volcanic and impact-induced ice depressions on Mars.  Icarus:  285, 185–194.</ref> <ref>University of Texas at Austin. "A funnel on Mars could be a place to look for life." ScienceDaily. ScienceDaily, 10 November 2016. <https://www.sciencedaily.com/releases/2016/11/161110125408.htm>.</ref>
  
 
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Revision as of 13:18, 27 March 2020

Mars topography (MOLA dataset) HiRes (1).jpg
MC-05 Ismenius Lacus 30–65° N 0–60° E Quadrangles Atlas


This quadrangle has some of the most mysterious-looking landscapes on the planet. It truly looks like another world here. Strong evidence of a past ocean on Mars exists in this region and is described below. The Ismenius Lacus quadrangle contains regions called Deuteronilus Mensae and Protonilus Mensae, two places that are of special interest to scientists. They contain abundant evidence of present and past glacial activity. They also have a landscape unique to Mars, called Fretted terrain. The largest crater in the area is Lyot Crater, which contains channels probably carved by liquid water.[1]

The Ismenius Lacus quadrangle is located in the northern hemisphere and covers 30° to 65° north latitude and 300° to 360° west longitude (60° to 0° east longitude). The southern and northern borders of the Ismenius Lacus quadrangle are approximately 3065 km (1,905 mi) and 1500 km wide (930 mi) respectively. The north-to-south distance is about 2050 km (1,270 mi) (a bit less than the length of Greenland).[2] The Ismenius Lacus quadrangle contains parts of regions named Acidalia Planitia, Arabia Terra, Vastitas Borealis, and Terra Sabaea.[3]

In this article, some of the best pictures from a number of spacecraft will show what the landscape looks like in this region. The origins and significance of all features will be explained as they are currently understood.

Origin of names

Ismenius Lacus is the name of a classical albedo feature located at 40° N and 30° E on Mars. Like most names for Martian places, Ismenius comes from old myths and stories. The term is Latin for Ismenian Lake, and refers to the Ismenian Spring near Thebes in Greece where Cadmus slew the guardian dragon. Cadmus was the legendary founder of Thebes, and had come to the spring to fetch water. The name was approved by the International Astronomical Union (IAU) in 1958.[4] All names suggested for astronomical features have to eventually approved by the International Astronomical Union (IAU).

Some important areas in this quadrangle derive from the names of canals that some early astronomers saw in this broad area. One such large canal they called Nilus. Since 1881–1882 it was split into other canals, some were called Nilosyrtis, Protonilus (first Nile),and Deuteronilus (second Nile).[5]

Ocean

Channels that may have been made by the backwash of tsunamis in an ocean Image is from HiRISE under the HiWish program

Channels made by the backwash from tsunamis, tsunamis were probably caused by asteroids striking an ocean. Image is from HiRISE under the HiWish program

Many researchers have suggested that Mars once had a great ocean in the north.[6] [7] [8] [9] [10] [11] [12] Much evidence for this ocean has been gathered over several decades. New evidence was published in May 2016. A large team of scientists described how some of the surface in Ismenius Lacus quadrangle was altered by two tsunamis. The tsunamis were caused by asteroids striking the ocean. Both were thought to have been strong enough to create 30 km diameter craters. The first tsunami picked up and carried boulders the size of cars or small houses. The backwash from the wave formed channels by rearranging the boulders. The second came in when the ocean was 300 m lower. The second carried a great deal of ice which was dropped in valleys. Calculations show that the average height of the waves would have been 50 m, but the heights would vary from 10 to 120 meters. So, some large waves would have gone over a 36 story building.[13] Numerical simulations show that in this particular part of the ocean two 30 km in diameter would form every 30 million years. The implication here is that a great northern ocean may have existed for millions of years. One argument against an ocean has been the lack of shoreline features. These features may have been washed away by these tsunami events. The parts of Mars studied in this research are Chryse Planitia and northwestern Arabia Terra. These tsunamis affected some surfaces in the Ismenius Lacus quadrangle and in the Mare Acidalium quadrangle.[14] [15] [16] [17]


Channels (Rivers)

Meanders Meanders are commonly formed in old river systems when the water is moving slowly.

               Meanders   They are formed in old river systems when the water is moving slowly.  

Many features were probably rivers with water flowing in them billions of years ago. Pictures below show many channels and parts of channels.


The channel shown below goes quite a long distance and has branches. It ends in a depression that may have been a lake at one time. The first picture is a wide angle, taken with CTX; while the second is a close up taken with HiRISE.[18]


Some places (like below) display a smaller channel within a larger, wider channel or valley. When this occurs it means water went through the region at least two times in the past. This implies that water was not just here once for a short period of time.


Channels that empty into a low area that could have been a lake, as seen by HiRISE under HiWish program

Channels that empty into a possible lake, as seen by HiRISE under HiWish program

Lyot Crater

The vast northern plains of Mars are generally flat and smooth with few craters. However, a few large craters do stand out. The giant impact crater, Lyot, is easy to see in the northern part of Ismenius Lacus. There are only a very few craters along the far northern latitudes.[19] Lyot Crater is the deepest point in Mars's northern hemisphere.[20] One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and Dust Devil Tracks. Dust devils, which resemble miniature tornados, create tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. It does not take too much fine dust to cover those tracks--experiments in Earth laboratories demonstrate that only a few 10's of microns of dust will do the trick. Note on units: a micron is an older name for micrometre or micrometer. The width of a single human hair ranges from approximately 20 to 200 microns (μm); hence, the dust that can cover dust devil tracks may only be the thickness of a human hair.[21] Light-toned materials are an important find because they are widely believed to contain minerals formed in water. Research, published in June 2010, described evidence for liquid water in Lyot crater in the past.

Many channels have been found near Lyot Crater. Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick. Calculations suggest that the ejecta would have had a temperature of at least 250 degrees Fahrenheit. The valleys seem to start from beneath the ejecta near the outer edge of the ejecta. The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean; channels in Lyot came after we had thought that Mars had dried up. So Mars had flowing water later then we believed.[22] [23] [24]

Wide view of channels in Lyot Crater, as seen by HiRISE under HiWish program Wide view of channels in Lyot Crater, as seen by HiRISE under HiWish program

Other craters

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 km in diameter), they usually have a central peak.[25] The peak is caused by a rebound of the crater floor following the impact.[26] Sometimes craters will display layers in their walls. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed unto the surface. Hence, craters are useful for showing us what lies deep under the surface.

Northeast rim of Quenisset Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Arrows indicate old glaciers. |Northeast rim of Quenisset Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter). Arrows indicate old glaciers.

Deltas

Researchers have found a number of examples of deltas that formed in Martian lakes. Deltas are major signs that Mars once had a lot of water because deltas usually require deep water over a long period of time to form. In addition, the water level needs to be stable to keep sediment from washing away. Deltas have been found over a wide geographical range. Below, is a pictures of a one in the Ismenius Lacus quadrangle.[29]


Fretted terrain

The Ismenius Lacus quadrangle contains several interesting features such as fretted terrain, parts of which are found in Deuteronilus Mensae and Protonilus Mensae. Fretted terrain contains smooth, flat lowlands along with steep cliffs. The scarps or cliffs are usually 1 to 2 km high. Channels in the area have wide, flat floors and steep walls. Many buttes and mesas are present. In fretted terrain the land seems to transition from narrow straight valleys to isolated mesas.[30] Most of the mesas are surrounded by forms that have been called a variety of names: circum-mesa aprons, debris aprons, rock glaciers, and lobate debris apron (LDA)s. The flat floors here often display many lines or lineations that scientists call lineated valley fill (LVF). These are caused by glacier-like flow. [31] At first they appeared to resemble rock glaciers on Earth. But scientists could not be sure. Even after the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) took a variety of pictures of fretted terrain, experts could not tell for sure if material was moving or flowing as it would in an ice-rich deposit (glacier). Eventually, proof of their true nature was discovered by radar studies with the Mars Reconnaissance Orbiter showed that they contain pure water ice covered with a thin layer of rocks that insulated the ice.[32] [33]

Wide CTX view showing mesa and buttes with lobate debris aprons and lineated valley fill around them. Wide CTX view showing mesa and buttes with lobate debris aprons and lineated valley fill around them. These are typical features of fretted terrain

Glaciers

Flow, as seen by HiRISE under HiWish program

                 Glacier, as seen by HiRISE under HiWish program

The Ismenius Lacus quadrangle might well be called the land of glaciers. Glaciers formed much of the observable surface in large areas of Mars. Much of the area in high latitudes, especially the Ismenius Lacus quadrangle, is believed to still contain enormous amounts of water ice.[34] [35] [36] In March 2010, scientists released the results of a radar study of an area called Deuteronilus Mensae that found widespread evidence of ice lying beneath a few meters of rock debris.[37] The ice was probably deposited as snowfall during an earlier climate when the poles were tilted more.[38] It would be difficult to take a hike on the fretted terrain where glaciers are common because the surface is folded, pitted, and often covered with linear striations.[39] The striations show the direction of movement. Much of this rough texture is due to sublimation of buried ice. The ice goes directly into a gas (this process is called sublimation) and leaves behind an empty space. Overlying material then collapses into the void.[40] Glaciers are not pure ice; they contain dirt and rocks. At times, they will dump their load of materials into ridges. Such ridges are called moraines.

Close-up of lobate debris apron from the previous CTX image of a mesa. Image shows open-cell brain terrain and closed-cell brain terrain, which is more common. Open-cell brain terrain is thought to hold a core of ice. Close-up of lobate debris apron from the previous CTX image of a mesa. Image shows open-cell brain terrain and closed-cell brain terrain, which is more common. Open-cell brain terrain is thought to hold a core of ice.

Latitude dependent mantle

Much of the Martian surface is covered with a thick ice-rich, mantle layer that has fallen from the sky a number of times in the past.[41] [42] [43]

Climate change caused ice-rich features

Many features on Mars, especially ones found in the Ismenius Lacus quadrangle, are believed to contain large amounts of ice. The most popular model for the origin of the ice is climate change from large changes in the tilt of the planet's rotational axis. At times the tilt has even been greater than 80 degrees[44] [45] Large changes in the tilt explains many ice-rich features on Mars.

Studies have shown that when the tilt of Mars reaches 45 degrees from its current 25 degrees, ice is no longer stable at the poles.[46] Furthermore, at this high tilt, stores of solid carbon dioxide (dry ice) sublimate, thereby increasing the atmospheric pressure. This increased pressure allows more dust to be held in the atmosphere. Moisture in the atmosphere will fall as snow or as ice frozen onto dust grains. Calculations suggest this material will concentrate in the mid-latitudes, like those of the Ismenius Lacus quadrangle.[47] [48] General circulation models of the Martian atmosphere predict accumulations of ice-rich dust in the same areas where ice-rich features are found.[49] When the tilt begins to return to lower values, the ice sublimates (turns directly to a gas) and leaves behind a lag of dust.[50] [51] The lag deposit caps the underlying material so with each cycle of high tilt levels, some ice-rich mantle remains behind.[52] Note, that the smooth surface mantle layer probably represents only relative recent material.

Upper Plains Unit

Remnants of a 50–100 meter thick mantling, called the Upper Plains Unit, has been discovered in the mid-latitudes of Mars. It was first investigated in the Deuteronilus Mensae region, but it occurs in other places as well. The remnants consist of sets of dipping layers in craters and along mesas.[53] [54] Sets of dipping layers may be of various sizes and shapes—some look like Aztec pyramids from Central America.

Associated with this unit are dipping layers. However, these groups of layers are found in many locations around the planet. They may be mostly caused by the build up and later erosion of layers of mantle. Mantle has been built up from many climate changes. These "dipping layers" occur mainly in protected spots--like inside craters or against the steep slope of a mesa or the walls of a depression.

This unit also degrades into "brain terrain." Brain terrain is a region of maze-like ridges 3–5 meters high. Some ridges may consist of an ice core, so they may be sources of water for future colonists.

Some regions of the upper plains unit display large fractures and troughs with raised rims; such regions are called ribbed upper plains. Fractures are believed to have started with small cracks from stresses. Stress is suggested to initiate the fracture process since ribbed upper plains are common when debris aprons come together or near the edge of debris aprons—such sites would generate compressional stresses. Cracks exposed more surfaces, and consequently more ice in the material sublimates into the planet's thin atmosphere. Eventually, small cracks become large canyons or troughs.

View of stress cracks and larger cracks that have been enlarged by sublimation (ice changing directly into gas) This may be the start of ribbed terrain. View of stress cracks and larger cracks that have been enlarged by sublimation (ice changing directly into gas) This may be the start of ribbed terrain.



Close view of terrain caused by ice leaving the ground Box shows size of football field. Close view of terrain caused by ice leaving the ground Box shows size of football field.

Small cracks often contain small pits and chains of pits; these are thought to be from sublimation of ice in the ground.[55] [56] Large areas of the Martian surface are loaded with ice that is protected by a meters thick layer of dust and other material. However, if cracks appear, a fresh surface will expose ice to the thin atmosphere.[57] [58] In a short time, the ice will disappear into the cold, thin atmosphere in a process called "sublimation." Dry ice behaves in a similar fashion on the Earth. On Mars sublimation has been observed when the Phoenix lander uncovered chunks of ice that disappeared in a few days.[59] [60] In addition, HiRISE has seen fresh craters with ice at the bottom. After a time, HiRISE saw the ice deposit disappear.[61]

The upper plains unit is thought to have fallen from the sky. It drapes various surfaces, since it fell evenly onto all surfaces. As is the case for other mantle deposits, the upper plains unit has layers, is fine-grained, and is ice-rich. It is widespread; it does not seem to have a point source. The surface appearance of some regions of Mars is due to how this unit has degraded. It is a major cause of the surface appearance of lobate debris aprons.[62] The layering of the upper plains mantling unit and other mantling units are believed to be caused by major changes in the planet's climate. Models predict that the obliquity or tilt of the rotational axis has varied from its present 25 degrees to maybe over 80 degrees over geological time. Periods of high tilt will cause the ice in the polar caps to be redistributed and change the amount of dust in the atmosphere.[63] [64] [65]

Pits and cracks

Some places in the Ismenius Lacus quadrangle display large numbers of cracks and pits. It is widely believed that these are the result of ground ice sublimating (changing directly from a solid to a gas). After the ice leaves, the ground collapses in the shape of pits and cracks. The pits may come first. When enough pits form, they unite to form cracks.[66]

Close view of lines of pits Box shows size of football field. Pits may be up to around 50 meters across.

Close view of lines of pits Box shows size of football field. Pits may be up to around 50 meters across.


Mesas formed by ground collapse

Polygonal patterned ground

Polygonal, patterned ground is quite common in some regions of Mars.[67] [68] [69] [70] [71] [72] [73] It is commonly believed to be a marker for ice-rich ground because these shapes are common on the Earth in cold regions with lots of ice in the ground. Places on Mars that display polygonal ground may indicate where future colonists can find water ice. Patterned ground forms in a mantle layer, called latitude dependent mantle, that fell from the sky when the climate was different.[74] [75]

Low center polygons

                             Low center polygons


Gullies

Gullies were thought for a time to have been caused by recent flows of liquid water. However, further study suggests they are formed today by chunks of dry ice moving down steep slopes.[76]

Layered features

Dunes

Wide view of a field of dunes

                 Wide view of a field of dunes

Sand dunes have been found in many places on Mars. The presence of dunes shows that the planet has an atmosphere with wind, for dunes require wind to pile up the sand. Most dunes on Mars are black because of the weathering of the volcanic rock basalt.[77] [78] Black sand can be found on Earth on Hawaii and on some tropical South Pacific islands.[79] Sand is common on Mars due to the old age of the surface that has allowed rocks to erode into sand. Dunes on Mars have been observed to move many meters.[80] [81] In this process, sand moves up the windward side and then falls down the leeward side of the dune, thus caused the dune to go toward the leeward side (or slip face).[82] When images are enlarged, some dunes on Mars display ripples on their surfaces.[83]

Ring mold craters

Ring Mold Craters are a kind of Impact crater that looks like a ring mold used in baking. They are believed to be caused by an impact into ice. The ice is covered by a layer of debris. They are found in parts of Mars that have buried ice. Laboratory experiments confirm that impacts into ice result in a "ring mold shape." Impacts into ice, warm the ice, and cause it to flow into the ring mold shape.

Ring-mold craters form when an impact goes through to an ice layer. The rebound forms the ring-mold shape, and then dust and debris settle on the top to insulate the ice. Ring-mold craters form when an impact goes through to an ice layer. The rebound forms the ring-mold shape, and then dust and debris settle on the top to insulate the ice.


Volcanoes under ice

There is evidence that volcanoes sometimes erupt under ice, as they do on Earth at times. What seems to happen is that much ice melts, the water escapes, and then the surface cracks and collapses.[84] These exhibit concentric fractures and large pieces of ground that seemed to have been pulled apart. Sites like this may have recently had held liquid water, hence they may be fruitful places to search for evidence of life.[85] [86]

Mesas formed by ground collapse

Fractures forming blocks

In places large fractures break up surfaces. Sometimes straight edges are formed and large cubes are created by the fractures.

Exhumed craters

Some features on Mars seem to be in the process of being uncovered. So, the thought is that they formed, were covered over, and now are being exhumed as material is being taken away by erosion. These features are quite noticeable with craters. When a crater forms, it will destroy what's under it and leave a rim and ejecta. In the example below, only part of the crater is visible. If the crater came after the layered feature, the impact that formed the crater would have removed part of the layered structure.


Mounds

Landslide


Other images from Ismenius Lacus quadrangle

Close view of honeycomb shapes and brain terrain, as seen by HiRISE under HiWish program Close view of honeycomb shapes and brain terrain, as seen by HiRISE under HiWish program


Ridges

                            Ridges

See also

External links

References

  1. Carter | first1 = J. | last2 = Poulet | first2 = F. | last3 = Bibring | first3 = J.-P. | last4 = Murchie | first4 = S. | year = 2010 | title = Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars | url = | journal = Science | volume = 328 | issue = 5986| pages = 1682–1686 |
  2. Distances calculated using NASA World Wind measuring tool. http://worldwind.arc.nasa.gov/.
  3. http://planetarynames.wr.usgs.gov/SearchResults?target=MARS&featureType=Terra,%20terrae
  4. USGS Gazetteer of Planetary Nomenclature. Mars. http://planetarynames.wr.usgs.gov/.
  5. Blunck, J. 1982. Mars and its Satellites. Exposition Press. Smithtown, N.Y.
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  7. Fairén | first1 = A. G. |display-authors=etal | year = 2003 | title = Episodic flood inundations of the northern plains of Mars | url = http://eprints.ucm.es/10431/1/9-Marte_3.pdf%7C journal = Icarus | volume = 165 | issue = 1| pages = 53–67 |
  8. Head | first1 = J. W. |display-authors=etal | year = 1999 | title = Possible ancient oceans on Mars: Evidence from Mars Orbiter Laser Altimeter data | url = | journal = Science | volume = 286 | issue = 5447| pages = 2134–2137 | doi=10.1126/science.286.5447.2134| pmid = 10591640 |
  9. Parker, T. J., Saunders, R. S. & Schneeberger, D. M. Transitional morphology in west Deuteronilus Mensae, Mars: Implications for modification of the lowland/upland boundary" Icarus 1989; 82, 111–145
  10. Carr | first1 = M. H. | last2 = Head | first2 = J. W. | year = 2003 | title = Oceans on Mars: An assessment of the observational evidence and possible fate | url = | journal = J. Geophys. Res. | volume = 108 | issue = E5| page = 5042 |
  11. Kreslavsky | first1 = M. A. | last2 = Head | first2 = J. W. | year = 2002| title = Fate of outflow channel effluent in the northern lowlands of Mars: The Vastitas Borealis Formation as a sublimation residue from frozen ponded bodies of water | url = | journal = J. Geophys. Res. | volume = 107 | issue = E12| page = 5121 |
  12. Clifford, S. M. & Parker, T. J. The evolution of the martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains" Icarus 2001; 154, 40–79
  13. https://www.convertunits.com/from/metre/to/story
  14. Ancient Tsunami Evidence on Mars Reveals Life Potential |date=May 20, 2016 |url=http://astrobiology.com/2016/05/ancient-tsunami-evidence-on-mars-reveals-life-potential.html
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