Difference between revisions of "Elysium quadrangle"

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This quadrangle was named after Elysium, a place of reward (Heaven), according to Homer in the Odyssey.<ref>Blunck, J.  1982.  Mars and its Satellites.  Exposition Press.  Smithtown, N.Y.</ref>
This quadrangle was named after Elysium, a place of reward (Heaven), according to Homer in the Odyssey.<ref>Blunck, J.  1982.  Mars and its Satellites.  Exposition Press.  Smithtown, N.Y.</ref>


The Elysium quadrangle covers the area between 180° to 225° west longitude (180 E-135 E) and 0° to 30° north latitude on Mars. A small part of the [[Medusae Fossae Formation]] lies in this quadrangle.  Eddie, Lockyer, and Tombaugh are the largest craters in the Elysium quadrangle. Elysium Mons and Albor Tholus are large volcanoes in this quadrangle.  Just outside the boundaries of Elysium quadrangle sits another large volcano called Hecates.  There are possible  giant river valleys in this area.  Athabasca Valles  may be one of the youngest on the planet. A large lake may once have existed in the south near Lethe Valles and Athabasca Valles.<ref>"Cabrol, N 2010">Cabrol, N. and E. Grin (eds.).  2010.  Lakes on Mars.  Elsevier.  NY.</ref>
The Elysium quadrangle covers the area between 180° to 225° west longitude (180 E-135 E) and 0° to 30° north latitude on Mars. A small part of the Medusae Fossae Formation lies in this quadrangle.  Eddie, Lockyer, and Tombaugh are the largest craters in the Elysium quadrangle. Elysium Mons and Albor Tholus are large volcanoes in this quadrangle.  Just outside the boundaries of Elysium quadrangle sits another large volcano called Hecates.  There are possible  giant river valleys in this area.  Athabasca Valles  may be one of the youngest on the planet. A large lake may once have existed in the south near Lethe Valles and Athabasca Valles.<ref>"Cabrol, N 2010">Cabrol, N. and E. Grin (eds.).  2010.  Lakes on Mars.  Elsevier.  NY.</ref>


The [[InSight]] lander touched down in the southern part of this quadrangle in 2018 and is now gathering data especially on Marsquakes.  InSight made a soft landing as planned on November 26, 2018 at 4.502 °N, 135.623 °E.  InSight landed in a crater that is 25 meters in diameter called Homestead hollow.  <ref>Banerdt B et al.: Initial results from the InSight mission on Mars, Nature Geoscience, 24 February 2020, doi: 10.1038/s41561-​020-0544-y</ref>   
The InSight lander touched down in the southern part of this quadrangle in 2018 and is now gathering data especially on Marsquakes.  InSight made a soft landing as planned on November 26, 2018 at 4.502 °N, 135.623 °E.  InSight landed in a crater that is 25 meters in diameter called Homestead Hollow.  <ref>Banerdt B et al.: Initial results from the InSight mission on Mars, Nature Geoscience, 24 February 2020, doi: 10.1038/s41561-​020-0544-y</ref>   
 
This article continues with pictures of significant features.  Pictures displayed here were taken with various spacecraft from Mars orbit:  Mars Odyssey, Mars Global Surveyor, and Mars Reconnaissance  Orbiter.  Most pictures from the Mars Reconnaissance Orbiter were taken with HiRISE under the [[HiWish program]].




==Volcanoes==
==Volcanoes==


The area near the volcanoes of Elysium is covered with lava flows.  On close examination, some flows can even be seen to approach and then stop when reaching higher ground.  (See pictures below for examples) The top of a lava flow often cools quickly , forming a hard crust, but it still moves under the crust.  Such movement breaks up the top layer making it very rough.<ref>http://hirise.lpl.arizona.edu/PSP_010744_1840 | title=Southern Margin of Cerberus Palus (PSP_010744_1840) |</ref>  Such rough flow is called aa lava.  The lava flows here are of the aa variety.
[[Image: Albor Tholus THEMIS.jpg |thumb|right|px|Albor Tholus as seen by THEMIS]]
 
[[Image:Elysium Mons THEMIS.jpg|200px|[[2001 Mars Odyssey]]'' Thermal Emission Imaging System|THEMIS daytime infrared image mosaic]]
 
Elysium Mons in center, Albor Tholus lower right
 
2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) daytime infrared image mosaic
 
 
 
 
The area near the volcanoes of Elysium is covered with lava flows.  On close examination, some flows can even be seen to approach and then stop when reaching higher ground.  (See pictures below for examples) The top of a lava flow often cools quickly, forming a hard crust, but lava still moves under the crust.  Such movement breaks up the top layer making it very rough.<ref>http://hirise.lpl.arizona.edu/PSP_010744_1840 | title=Southern Margin of Cerberus Palus (PSP_010744_1840) |</ref>  Such rough flow is called aa lava.  The lava flows here are of the aa variety.


Some places in the Elysium quadrangle are young geological. Some researchers call them  Platy-Ridged-Polygonized terrain.  The surface of this terrain has been suggested to be pack ice, basalt lava, or muddy flows.  HiRISE images show the heights of the surface ridges to be usually less than 2 meters.  This is far less than what is expected from lava flows.  In addition the high resolution photos of HiRISE indicates that the surface appears to flow.  This would not occur with pack ice.  So, the researchers concluded that muddy flows cover the surface.<ref>Yue, Z., et al.  2017.  AN INVESTIGATION OF THE HYPOTHESES FOR FORMATION OF THE PLATY-RIDGEDPOLYGONIZED TERRAIN IN ELYSIUM PLANITIA, MARS.  Lunar and Planetary Science XLVIII (2017).  1770.pdf</ref>  For a while, many believed the surface was made of ice flows, which it resembles.
Some places in the Elysium quadrangle are young geological. Some researchers call them  Platy-Ridged-Polygonized terrain.  The surface of this terrain has been suggested to be pack ice, basalt lava, or muddy flows.  HiRISE images show the heights of the surface ridges to be usually less than 2 meters--far less than what is expected from lava flows.  In addition, the high resolution photos of HiRISE indicates that the surface appears to flow.  This would not occur with pack ice.  So, the researchers concluded that muddy flows cover the surface.<ref>Yue, Z., et al.  2017.  AN INVESTIGATION OF THE HYPOTHESES FOR FORMATION OF THE PLATY-RIDGEDPOLYGONIZED TERRAIN IN ELYSIUM PLANITIA, MARS.  Lunar and Planetary Science XLVIII (2017).  1770.pdf</ref>  For a while, many believed the surface was made of ice flows, which it sort of resembles.


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<gallery class="center"  widths="380px" heights="360px">


Image:Lava flow in Elysium.JPG|Lava flow in Elysium. There are many lava flows in Elysium. In this one, the lava flowed toward the upper right. Image taken by [[Mars Global Surveyor]], under the MOC Public Targeting Program.
Image:Lava flow in Elysium.JPG|Lava flow in Elysium. There are many lava flows in Elysium. In this one, the lava flowed toward the upper right. Image taken by [[Mars Global Surveyor]], under the MOC Public Targeting Program.


ESP 051990 2045lavaflows.jpg|Lava flow, as seen by HiRISE under HiWish program  [[Dark slope streaks]] are also visible
ESP 051990 2045lavaflows.jpg|Lava flow, as seen by HiRISE under [[HiWish program]] [[Dark slope streaks]] are also visible


Image:Lava flows in Elysium.JPG|Lava flows in Elysium as seen by [[HiRISE]]. Upper part of image shows lava that solidified on the top then crumpled as lava still moved.
Image:Lava flows in Elysium.JPG|Lava flows in Elysium as seen by HiRISE. Upper part of image shows lava that solidified on the top then crumpled as lava still moved.


File:ESP 053269 2080lavaflow.jpg|Lava flow,  as seen by HiRISE under HiWish program
File:ESP 053269 2080lavaflow.jpg|Lava flow


File:ESP 054891 2040lavarafts.jpg|Lava rafts, as seen by HiRISE under HiWish program
File:ESP 054891 2040lavarafts.jpg|Lava rafts


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==Rootless cones==
==Rootless cones==


[[File:ESP 052267 2065rootlesscones.jpg|Wide view of field of rootless cones ]]
[[File:52267 2065rootlessconesclose.jpg |Close view of field of rootless cones, as seen by HiRISE under HiWish program]]
 
 
                      Close view of field of rootless cones, as seen by HiRISE under HiWish program


"Rootless cones" are caused by explosions of lava with ground ice under a hot lava flow.<ref>Keszthelyi, L. et al.  2010. Hydrovolcanic features on Mars: Preliminary observations from the first Mars year of HiRISE.  Icarus:  205, 211-229. imaging</ref> <ref>http://www.psrd.hawaii.edu/June01/lavaIceMars.html</ref> <ref>Lanagan, P., A.  McEwen, L. Keszthelyi, and T. Thordarson.  2001.  Rootless cones on Mars indicating the presence of shallow equatorial ground ice in recent times, Geophysical Research Letters: 28, 2365-2368.</ref>  The ice melts and turns into a vapor and creates a cone or ring.  These cones are found in Iceland, in places where lava covers water-saturated ground.<ref>S. Fagents1, A.,  P. Lanagan, R. Greeley.  2002.  Rootless cones on Mars: a consequence of lava-ground ice interaction.  Geological Society, Londo. Special Publications:  202, 295-317.</ref> <ref>http://www.psrd.hawaii.edu/June01/lavaIceMars.</ref> <ref>Jaeger, W., L. Keszthelyi, A. McEwen, C. Dundas, P. Russell, and the HiRISE team.  2007.  EARLY HiRISE OBSERVATIONS OF RING/MOUND LANDFORMS IN ATHABASCA VALLES, MARS.  Lunar and Planetary Science XXXVIII 1955.pdf.</ref>


<gallery class="centerwidths="190px" heights="180px" >
"Rootless cones" are caused by explosions of lava with ground ice.<ref>Keszthelyi, L. et al.  2010. Hydrovolcanic features on Mars: Preliminary observations from the first Mars year of HiRISE.  Icarus:  205, 211-229. imaging</ref> <ref>http://www.psrd.hawaii.edu/June01/lavaIceMars.html</ref> <ref>Lanagan, P., A.  McEwen, L. Keszthelyi, and T. Thordarson.  2001.  Rootless cones on Mars indicating the presence of shallow equatorial ground ice in recent times, Geophysical Research Letters: 28, 2365-2368.</ref>  The ice melts and turns into a vapor and creates a cone or ring.  These cones are found in Iceland, in places where lava covers water-saturated ground.<ref>S. Fagents1, A., P. Lanagan, R. Greeley.  2002.  Rootless cones on Mars: a consequence of lava-ground ice interaction.  Geological Society, Londo. Special Publications:  202, 295-317.</ref> <ref>http://www.psrd.hawaii.edu/June01/lavaIceMars.</ref> <ref>Jaeger, W., L. Keszthelyi, A. McEwen, C. Dundas, P. Russell, and the HiRISE team.  2007.  EARLY HiRISE OBSERVATIONS OF RING/MOUND LANDFORMS IN ATHABASCA VALLES, MARS.  Lunar and Planetary Science XXXVIII 1955.pdf.</ref>


52267 2065rootlessconesclose.jpg|Close view of field of rootless cones, as seen by HiRISE under HiWish program
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File:ESP 052267 2065rootlesscones.jpg|Wide view of field of rootless cones  


Image:Rootless Cones.jpg|Rootless Cones, as seen by HiRISE.  The chains of rings caused by lava interacting with water ice.
Image:Rootless Cones.jpg|Rootless Cones, as seen by HiRISE.  The chains of rings caused by lava interacting with water ice.
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Image:Layers in Monument Valley.jpg|Layers in Monument Valley. These are accepted as being formed, at least in part, by water deposition. Since Mars contains similar layers, water remains as a major cause of layering on Mars.
Image:Layers in Monument Valley.jpg|Layers in Monument Valley.  


ESP 046136 1960layers.jpg|Layers around base of mound
ESP 046136 1960layers.jpg|Layers around base of mound
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[[File:Troughs in Elysium Planitia.JPG |Troughs to the east of Albor Tholus]]
[[File:Troughs in Elysium Planitia.JPG |Troughs to the east of Albor Tholus]]


Troughs to the east of Albor Tholus  HiRISE images only have a color strip in the center.


Long, narrow depressions are common on Mars.  They are called troughs or fossae in the geographical language used for Mars. Troughs may be made when the crust is stretched until it breaks. The mass of  the huge volcanoes can cause this stretching. Fossae and common in the Elysium quadrangle as are volcanoes.  A trough often possesses two breaks or faults with a middle section moving down.  This leaves steep cliffs along the sides and is called a graben.<ref>http://hirise.lpl.arizona.edu/PSP_008641_2105</ref>  Lake George, in northern New York State, is a lake inside a graben. Pits are often associated with troughs.  Troughs often appear to begin as a line of pits.  Pits result when material collapses into a void.  Pits do not have rims or ejecta around them, like impact craters do.<ref>Wyrick, D., D. Ferrill, D. Sims, and S. Colton. 2003. Distribution, Morphology and Structural Associations of Martian Pit Crater Chains. Lunar and Planetary Science XXXIV (2003)</ref>  There are other ideas for the formation of fossae and pits or pit craters as they are called. They may be connected to dikes of magma. Dikes form when magma moving underground travels upward along a fault or break in the rock.  Magma might move along, under the surface, breaking the rock, and more importantly melting ice. The resulting action would cause a crack to form at the surface. The images below of the [[Cerberus Fossae]], the [[Elysium Fossae]] and other troughs, as seen by [[HiRISE]] are examples of fossae.
Troughs to the east of Albor Tholus  HiRISE images only have a color strip in the center.  Marquakes detected by InSight are originating in places like this.
 
 
Long, narrow depressions are common on Mars.  They are called troughs or fossae in the geographical language used for Mars. Troughs may be made when the crust is stretched until it breaks. The mass of  the huge volcanoes can cause this stretching. Fossae and common in the Elysium quadrangle as are volcanoes.  A trough often possesses two breaks or faults with a middle section lower.  This leaves steep cliffs along the sides and is called a graben.<ref>http://hirise.lpl.arizona.edu/PSP_008641_2105</ref>  Lake George, in northern New York State, is a lake inside a graben. Pits are often associated with troughs.  Troughs often appear to begin as a line of pits.  Pits result when material collapses into a void.  Pits do not have rims or ejecta around them, like impact craters do.<ref>Wyrick, D., D. Ferrill, D. Sims, and S. Colton. 2003. Distribution, Morphology and Structural Associations of Martian Pit Crater Chains. Lunar and Planetary Science XXXIV (2003)</ref>  Another explanation for the formation of fossae and pits or pit craters as they are called, is that they may be from dikes of magma. Dikes form when magma moving underground travels upward along a fault or break in the rock.  Magma might move along, under the surface, breaking the rock, and more importantly melting ice. The resulting action would cause a crack to form at the surface. The images below of the Cerberus Fossae, the Elysium Fossae and other troughs, as seen by HiRISE are examples of fossae.


Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be hold water.<ref>Ferrill, D., D. Wyrick, A. Morris, D. Sims, and N. Franklin. 2004. Dilational fault slip and pit chain formation on Mars 14:10:4-12</ref>
Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be hold water.<ref>Ferrill, D., D. Wyrick, A. Morris, D. Sims, and N. Franklin. 2004. Dilational fault slip and pit chain formation on Mars 14:10:4-12</ref>


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Image:Elysium Fossae.JPG|The Elysium Fossae, as seen by HiRISE (scale bar is 500 m)


Image:Elysium Fossae.JPG|The [[Elysium Fossae]], as seen by HiRISE (scale bar is 500 m)
Image:Troughs showing blue in Elysium Planitia.JPG|Portion of a trough (fossa) (blue indicates probably seasonal frost)<ref>https://www.uahirise.org/ESP_019033_2495</ref>


Image:Troughs showing blue in Elysium Planitia.JPG|Portion of a trough (fossa) (blue indicates probably seasonal frost)<ref>https://www.uahirise.org/ESP_019033_2495</ref>
ESP 045741 2080troughs.jpg|Troughs showing layers and dark slope streaks, as seen by HiRISE under HiWish program
ESP 045741 2080troughs.jpg|Troughs showing layers and dark slope streaks, as seen by HiRISE under HiWish program
File:ESP 055459 2080troughstreak.jpg|Trough
File:ESP 055459 2080troughstreak.jpg|Trough
File:55459 2080layersclose.jpg|Close view of layers in trough
File:55459 2080layersclose.jpg|Close view of layers in trough
File:ESP 057555 1820concentricfractures.jpg|Concentric troughs, as seen by HiRISE under the HiWish program


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             Close view of possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program
             Close view of possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program


Like nearly all of Mars, the surface of Elysium quadrangle contains numerous impact craters.  The large numbers are from the extreme age of most of the Martian surface.  Impact craters generally have a rim with ejecta around them; volcanic craters do not have a rim or ejecta deposits.  As craters get larger (greater than 10 km in diameter) they usually possess a central peak.<ref>http://www.lpi.usra.edu/publications/slidesets/stones/</ref> The peak is caused by a rebound of the crater floor following the impact.<ref>Hugh H. Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ|accessdate=7 March 2011|year=1992|publisher=University of Arizona Press|</ref>  Sometimes craters will display layers.  The collision that produces a crater brings rocks from deep underground.  Hence, craters can show us what lies deep under the surface.  Some craters are called "ring-mold" craters.  They resemble ring molds used to make cakes.  Some researches think they are caused by rebound from an ice layer.  If this is true, they may be sources of pure ice for future colonists of Mars.
Like nearly all of Mars, the surface of Elysium quadrangle contains numerous impact craters.  The large numbers of craters are a consequence of the extreme age of most of the Martian surface.  Older surfaces display more craters.  Impact craters generally have a rim with ejecta around them; volcanic craters do not have a rim or ejecta deposits.  As craters get larger (greater than 10 km in diameter) they usually possess a central peak.<ref>http://www.lpi.usra.edu/publications/slidesets/stones/</ref> The peak is caused by a rebound of the crater floor following the impact.<ref>Hugh H. Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ|accessdate=7 March 2011|year=1992|publisher=University of Arizona Press|</ref>  Sometimes craters will display layers.  The collision that produces a crater brings rocks from deep underground.  Hence, craters can show us what lies deep under the surface.  Some craters are called "ring-mold" craters.  They resemble ring molds used to make cakes.  Some researches think they are caused by rebound from an ice layer.  If this is true, they may be sources of pure ice for future colonists of Mars.




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Image:layers in Lockyer Crater.jpg|Layers in [[Lockyer Crater]], as seen by HiRISE under the [[HiWish program]]
Image:layers in Lockyer Crater.jpg|Layers in Lockyer Crater


Esp 036944 1810craters.jpg|Crater showing layers and small craters in the ejecta that show a thin ejecta pattern Image taken with HiRISE under HiWish program.
Esp 036944 1810craters.jpg|Crater showing layers and small craters in the ejecta that show a thin ejecta pattern


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File:ESP 053981 2090ringmolds.jpg|Possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program
File:ESP 053981 2090ringmolds.jpg|Possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program


File:ESP 054944 2085benchcrater.jpg|Crater with a bench, as seen by HiRISE under HiWish program
File:ESP 054944 2085benchcrater.jpg|Crater with a bench


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Streamlined shapes, as seen by HiRISE under HiWish program  These were probably shaped by running water.
Streamlined shapes, as seen by HiRISE under HiWish program  These were probably shaped by running water.


Some landscapes in the Elysium quadrangle show strong evidence for flowing water.  Channels that look like old river valleys are called Vallis in the language used for Mars.
Some landscapes in the Elysium quadrangle show strong evidence for flowing water.  Channels that look like old river valleys are called Vallis in the language used for Mars.
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Some valleys appear to start from grabens.  Granicus Vallis and Tinjar Vallis begin at grabens that lies just to the west of Elysium Mons. The grabens may have formed because of volcanic dikes.  Heat from the dikes would have melted a great deal of ice.  Remember dikes are walls of rock that were once hot, liquid magma that followed cracks or faults in the rock.<ref>Christiansen, E.  1989.  Lahars in the Elysium region of Mars.  Geology.  17:  203-206.</ref>  
Some valleys appear to start from grabens.  Granicus Vallis and Tinjar Vallis begin at grabens that lies just to the west of Elysium Mons. The grabens may have formed because of volcanic dikes.  Heat from the dikes would have melted a great deal of ice.  Remember dikes are walls of rock that were once hot, liquid magma that followed cracks or faults in the rock.<ref>Christiansen, E.  1989.  Lahars in the Elysium region of Mars.  Geology.  17:  203-206.</ref>  


The [[Athabasca Valles]] are perhaps the youngest outflow channel system on Mars. They lie 620 miles southeast of the large volcano [[Elysium Mons]]. Athabasca was created when water burst out of the [[Cerberus Fossae]], a set of cracks or fissures in the ground.<ref>Cabrol, N. and E. Grin (eds.).  2010.  Lakes on Mars.  Elsevier. NY</ref> <ref>Burr, D. et al.  2002.  Repeated aqueous flooding from the Cerberus Fossae: evidence for very recently extant deep groundwater on Mars.  Icarus.  159:  53-73.</ref> The [[Cerberus Fossae]] most likely were formed from the stress on the crust caused by the weight of both Elysium Mons and the Tharsis volcanoes. Current evidence suggests that Cerberus floods probably erupted in several stages.<ref>http://themis.asu.edu/features/athabascafloods | title=Feature Image: Floods in Athabasca Valles</ref>  Near the start of these channels (at one of the Cerberus Fossae), the system is called the Athabasca Valles; to the south and east it is called Marte Vallis. Flow rates in Marte Vallis have been estimated at around 100 times that of the Mississippi River. Eventually, the system just seems to fade out in the plains of Amazonis Planitia.<ref>Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.</ref>  Streamlined shapes here demonstrate that much water once moved though this area.
The Athabasca Valles are perhaps the youngest outflow channel system on Mars. They lie 620 miles southeast of the large volcano [[Elysium Mons]]. Athabasca was created when water burst out of the Cerberus Fossae, a set of cracks or fissures in the ground.<ref>Cabrol, N. and E. Grin (eds.).  2010.  Lakes on Mars.  Elsevier. NY</ref> <ref>Burr, D. et al.  2002.  Repeated aqueous flooding from the Cerberus Fossae: evidence for very recently extant deep groundwater on Mars.  Icarus.  159:  53-73.</ref> The Cerberus Fossae most likely were formed from the stress on the crust caused by the weight of both Elysium Mons and the Tharsis volcanoes. Current evidence suggests that Cerberus floods probably erupted in several stages.<ref>http://themis.asu.edu/features/athabascafloods | title=Feature Image: Floods in Athabasca Valles</ref>  Near the start of these channels (at one of the Cerberus Fossae), the system is called the Athabasca Valles; to the south and east it is called Marte Vallis. Water really gushed out of the ground.  Flow rates in Marte Vallis have been estimated at around 100 times that of the Mississippi River. Eventually, the system just seems to fade out in the plains of Amazonis Planitia.<ref>Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.</ref>  Streamlined shapes here demonstrate that much water once moved though this area.


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ESP 047494 1960streamlined.jpg|Streamlined forms in the Grjota Valles, as seen by HiRISE under HiWish program
ESP 047494 1960streamlined.jpg|Streamlined forms in the Grjota Valles, as seen by HiRISE under HiWish program


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Close view of fractured ground  Box shows size of football field.  The boulders are the size of houses.
                    Close view of fractured ground  Box shows size of football field.  The boulders are the size of houses.




Some places on Mars break up with large fractures that created a terrain with mesas and valleys.  They may have started with cracks that became larger and larger as ice in the ground disappeared by the process of sublimation.  In the thin atmosphere of Mars, ice will turn directly into a vapor.  Since the ground contains so much ice, when the ice leaves large canyons are formed.  Some of these can be quite beautiful.
Some places on Mars break up with large fractures that create a terrain with mesas and valleys.  They may have started with cracks that became larger and larger as ice in the ground disappeared by the process of sublimation.  In the thin atmosphere of Mars, ice will turn directly into a vapor.  Since the ground contains so much ice when the ice leaves, large canyons are formed.  Some of these can be quite beautiful.


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ESP 048878 2095fractures.jpg|Wide view of fractured ground
ESP 048878 2095fractures.jpg|Wide view of fractured ground


48878 2095fractures.jpg|Close view of fractured ground
48878 2095fractures.jpg|Close view of fractured ground
48878 2095fracturesboulders.jpg|Close view of fractured ground  Box shows size of football field.  The boulders are the size of houses.


ESP 048878 2095fracturesclosecolor.jpg|Close, color view of fractured ground, as seen by HiRISE under HiWish program
ESP 048878 2095fracturesclosecolor.jpg|Close, color view of fractured ground, as seen by HiRISE under HiWish program
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==Mesas==
==Mesas==
Mesas have a flat top and steep sides.  The top layer of a mesa is often called a cap rock because it protects the underlying layers from erosion.  Mesas often form from the erosion of a plateau.  Mesas represent the remnants of a plateau, so they can show us what types of rocks covered a wide region.  <ref>Namowitz, S., D. Stone.  earth science  The world we live in  1975.  American Book Company.  New York.</ref>
Mesas have a flat top and steep sides.  The top layer of a mesa is often called a cap rock because it protects the underlying layers from erosion.  Mesas often form from the erosion of a plateau.  Mesas represent the remnants of a plateau, so they can show us what types of rocks covered a wide region.  <ref>Namowitz, S., D. Stone.  earth science  The world we live in  1975.  American Book Company.  New York.</ref>


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ESP 045016 2080mesas.jpg|Wide view of Buttes and Mesas
ESP 045016 2080mesas.jpg|Wide view of Buttes and Mesas
45016 2080mesas2.jpg|Buttes and mesas
45016 2080mesas2.jpg|Mesa
45016 2080mesas.jpg|Mesas, as seen by HiRISE under HiWish program 


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<gallery class="center"  widths="190px" heights="180px" >
[[File:16 21 2117 monument valley.jpg|thumb|400px|center|Spearhead Mesa in Monument Valley  Note the flat top and steep walls that are characteristic of mesas.]]
16 21 2117 monument valley.jpg|Spearhead Mesa in Monument Valley  Note the flat top and steep walls that are characteristic of mesas.
 
</gallery>
 
 


[[File:45016 2080mesas.jpg|thumb|400px|right|Mesas, as seen by HiRISE under HiWish program  These are like the ones in Monument Valley]]


==See Also==
==See Also==
Line 215: Line 232:


*[[Water]]
*[[Water]]
==External links==
*[https://www.youtube.com/watch?v=kca3Y8XUK1c InSight Live Q&A: Journey to the Center of Mars with the Lander Team]


==References==
==References==

Latest revision as of 15:15, 26 July 2021

Mars topography (MOLA dataset) HiRes (1).jpg
MC-15 Elysium 0–30° N 135–180° E Quadrangles Atlas

This quadrangle was named after Elysium, a place of reward (Heaven), according to Homer in the Odyssey.[1]

The Elysium quadrangle covers the area between 180° to 225° west longitude (180 E-135 E) and 0° to 30° north latitude on Mars. A small part of the Medusae Fossae Formation lies in this quadrangle. Eddie, Lockyer, and Tombaugh are the largest craters in the Elysium quadrangle. Elysium Mons and Albor Tholus are large volcanoes in this quadrangle. Just outside the boundaries of Elysium quadrangle sits another large volcano called Hecates. There are possible giant river valleys in this area. Athabasca Valles may be one of the youngest on the planet. A large lake may once have existed in the south near Lethe Valles and Athabasca Valles.[2]

The InSight lander touched down in the southern part of this quadrangle in 2018 and is now gathering data especially on Marsquakes. InSight made a soft landing as planned on November 26, 2018 at 4.502 °N, 135.623 °E. InSight landed in a crater that is 25 meters in diameter called Homestead Hollow. [3]

This article continues with pictures of significant features. Pictures displayed here were taken with various spacecraft from Mars orbit: Mars Odyssey, Mars Global Surveyor, and Mars Reconnaissance Orbiter. Most pictures from the Mars Reconnaissance Orbiter were taken with HiRISE under the HiWish program.


Volcanoes

Albor Tholus as seen by THEMIS

THEMIS daytime infrared image mosaic

Elysium Mons in center, Albor Tholus lower right

2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) daytime infrared image mosaic



The area near the volcanoes of Elysium is covered with lava flows. On close examination, some flows can even be seen to approach and then stop when reaching higher ground. (See pictures below for examples) The top of a lava flow often cools quickly, forming a hard crust, but lava still moves under the crust. Such movement breaks up the top layer making it very rough.[4] Such rough flow is called aa lava. The lava flows here are of the aa variety.

Some places in the Elysium quadrangle are young geological. Some researchers call them Platy-Ridged-Polygonized terrain. The surface of this terrain has been suggested to be pack ice, basalt lava, or muddy flows. HiRISE images show the heights of the surface ridges to be usually less than 2 meters--far less than what is expected from lava flows. In addition, the high resolution photos of HiRISE indicates that the surface appears to flow. This would not occur with pack ice. So, the researchers concluded that muddy flows cover the surface.[5] For a while, many believed the surface was made of ice flows, which it sort of resembles.

Rootless cones

Close view of field of rootless cones, as seen by HiRISE under HiWish program


                     Close view of field of rootless cones, as seen by HiRISE under HiWish program


"Rootless cones" are caused by explosions of lava with ground ice.[6] [7] [8] The ice melts and turns into a vapor and creates a cone or ring. These cones are found in Iceland, in places where lava covers water-saturated ground.[9] [10] [11]

Layers

Layers around streamlined knob, as seen by HiRISE under HiWish program


Some regions in the Elysium quadrangle display strata or layers. Some layers break up into fine particles, other layers break up into large boulders due to their hardness. These boulders are probably made of the volcanic rock basalt since it is hard and is widespread on Mars. Some layers may be caused by repeated flows of lava.


Troughs/pit craters

Troughs to the east of Albor Tholus


Troughs to the east of Albor Tholus HiRISE images only have a color strip in the center. Marquakes detected by InSight are originating in places like this.


Long, narrow depressions are common on Mars. They are called troughs or fossae in the geographical language used for Mars. Troughs may be made when the crust is stretched until it breaks. The mass of the huge volcanoes can cause this stretching. Fossae and common in the Elysium quadrangle as are volcanoes. A trough often possesses two breaks or faults with a middle section lower. This leaves steep cliffs along the sides and is called a graben.[12] Lake George, in northern New York State, is a lake inside a graben. Pits are often associated with troughs. Troughs often appear to begin as a line of pits. Pits result when material collapses into a void. Pits do not have rims or ejecta around them, like impact craters do.[13] Another explanation for the formation of fossae and pits or pit craters as they are called, is that they may be from dikes of magma. Dikes form when magma moving underground travels upward along a fault or break in the rock. Magma might move along, under the surface, breaking the rock, and more importantly melting ice. The resulting action would cause a crack to form at the surface. The images below of the Cerberus Fossae, the Elysium Fossae and other troughs, as seen by HiRISE are examples of fossae.

Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be hold water.[14]


Concentric troughs, as seen by HiRISE under the HiWish program

                                  Concentric troughs, as seen by HiRISE under the HiWish program

Craters

Close view of possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program

           Close view of possible ring-mold craters on floor of large crater, as seen by HiRISE under the HiWish program

Like nearly all of Mars, the surface of Elysium quadrangle contains numerous impact craters. The large numbers of craters are a consequence of the extreme age of most of the Martian surface. Older surfaces display more craters. Impact craters generally have a rim with ejecta around them; volcanic craters do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually possess a central peak.[16] The peak is caused by a rebound of the crater floor following the impact.[17] Sometimes craters will display layers. The collision that produces a crater brings rocks from deep underground. Hence, craters can show us what lies deep under the surface. Some craters are called "ring-mold" craters. They resemble ring molds used to make cakes. Some researches think they are caused by rebound from an ice layer. If this is true, they may be sources of pure ice for future colonists of Mars.


Channels

Streamlined shapes, as seen by HiRISE under HiWish program These were probably shaped by running water.

Streamlined shapes, as seen by HiRISE under HiWish program These were probably shaped by running water.


Some landscapes in the Elysium quadrangle show strong evidence for flowing water. Channels that look like old river valleys are called Vallis in the language used for Mars.

Some valleys appear to start from grabens. Granicus Vallis and Tinjar Vallis begin at grabens that lies just to the west of Elysium Mons. The grabens may have formed because of volcanic dikes. Heat from the dikes would have melted a great deal of ice. Remember dikes are walls of rock that were once hot, liquid magma that followed cracks or faults in the rock.[18]

The Athabasca Valles are perhaps the youngest outflow channel system on Mars. They lie 620 miles southeast of the large volcano Elysium Mons. Athabasca was created when water burst out of the Cerberus Fossae, a set of cracks or fissures in the ground.[19] [20] The Cerberus Fossae most likely were formed from the stress on the crust caused by the weight of both Elysium Mons and the Tharsis volcanoes. Current evidence suggests that Cerberus floods probably erupted in several stages.[21] Near the start of these channels (at one of the Cerberus Fossae), the system is called the Athabasca Valles; to the south and east it is called Marte Vallis. Water really gushed out of the ground. Flow rates in Marte Vallis have been estimated at around 100 times that of the Mississippi River. Eventually, the system just seems to fade out in the plains of Amazonis Planitia.[22] Streamlined shapes here demonstrate that much water once moved though this area.


Channel network, as seen by HiRISE under HiWish program


                          Channel network, as seen by HiRISE under HiWish program

Fractured ground

Close view of fractured ground Box shows size of football field. The boulders are the size of houses.


                    Close view of fractured ground  Box shows size of football field.  The boulders are the size of houses.


Some places on Mars break up with large fractures that create a terrain with mesas and valleys. They may have started with cracks that became larger and larger as ice in the ground disappeared by the process of sublimation. In the thin atmosphere of Mars, ice will turn directly into a vapor. Since the ground contains so much ice when the ice leaves, large canyons are formed. Some of these can be quite beautiful.

Mesas

Mesas have a flat top and steep sides. The top layer of a mesa is often called a cap rock because it protects the underlying layers from erosion. Mesas often form from the erosion of a plateau. Mesas represent the remnants of a plateau, so they can show us what types of rocks covered a wide region. [23]

Spearhead Mesa in Monument Valley Note the flat top and steep walls that are characteristic of mesas.
Mesas, as seen by HiRISE under HiWish program These are like the ones in Monument Valley

See Also

External links

References

  1. Blunck, J. 1982. Mars and its Satellites. Exposition Press. Smithtown, N.Y.
  2. "Cabrol, N 2010">Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY.
  3. Banerdt B et al.: Initial results from the InSight mission on Mars, Nature Geoscience, 24 February 2020, doi: 10.1038/s41561-​020-0544-y
  4. http://hirise.lpl.arizona.edu/PSP_010744_1840 | title=Southern Margin of Cerberus Palus (PSP_010744_1840) |
  5. Yue, Z., et al. 2017. AN INVESTIGATION OF THE HYPOTHESES FOR FORMATION OF THE PLATY-RIDGEDPOLYGONIZED TERRAIN IN ELYSIUM PLANITIA, MARS. Lunar and Planetary Science XLVIII (2017). 1770.pdf
  6. Keszthelyi, L. et al. 2010. Hydrovolcanic features on Mars: Preliminary observations from the first Mars year of HiRISE. Icarus: 205, 211-229. imaging
  7. http://www.psrd.hawaii.edu/June01/lavaIceMars.html
  8. Lanagan, P., A. McEwen, L. Keszthelyi, and T. Thordarson. 2001. Rootless cones on Mars indicating the presence of shallow equatorial ground ice in recent times, Geophysical Research Letters: 28, 2365-2368.
  9. S. Fagents1, A., P. Lanagan, R. Greeley. 2002. Rootless cones on Mars: a consequence of lava-ground ice interaction. Geological Society, Londo. Special Publications: 202, 295-317.
  10. http://www.psrd.hawaii.edu/June01/lavaIceMars.
  11. Jaeger, W., L. Keszthelyi, A. McEwen, C. Dundas, P. Russell, and the HiRISE team. 2007. EARLY HiRISE OBSERVATIONS OF RING/MOUND LANDFORMS IN ATHABASCA VALLES, MARS. Lunar and Planetary Science XXXVIII 1955.pdf.
  12. http://hirise.lpl.arizona.edu/PSP_008641_2105
  13. Wyrick, D., D. Ferrill, D. Sims, and S. Colton. 2003. Distribution, Morphology and Structural Associations of Martian Pit Crater Chains. Lunar and Planetary Science XXXIV (2003)
  14. Ferrill, D., D. Wyrick, A. Morris, D. Sims, and N. Franklin. 2004. Dilational fault slip and pit chain formation on Mars 14:10:4-12
  15. https://www.uahirise.org/ESP_019033_2495
  16. http://www.lpi.usra.edu/publications/slidesets/stones/
  17. Hugh H. Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ%7Caccessdate=7 March 2011|year=1992|publisher=University of Arizona Press|
  18. Christiansen, E. 1989. Lahars in the Elysium region of Mars. Geology. 17: 203-206.
  19. Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY
  20. Burr, D. et al. 2002. Repeated aqueous flooding from the Cerberus Fossae: evidence for very recently extant deep groundwater on Mars. Icarus. 159: 53-73.
  21. http://themis.asu.edu/features/athabascafloods | title=Feature Image: Floods in Athabasca Valles
  22. Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.
  23. Namowitz, S., D. Stone. earth science The world we live in 1975. American Book Company. New York.