{{Short description|Map of Mars}} {{Infobox feature on celestial object |name = Ismenius Lacus quadrangle |image = [[File:USGS-Mars-MC-5-IsmeniusLacusRegion-mola.png|300px]] |caption = Map of Ismenius Lacus quadrangle from [[Mars Orbiter Laser Altimeter]] (MOLA) data. The highest elevations are red and the lowest are blue. |coordinates = {{coord|47.5|N|330|W|globe:mars_type:landmark|display=inline,title}} }} [[File:PIA00165-Mars-MC-5-IsmeniusLacusRegion-19980604.jpg|thumb|300px|Image of the Ismenius Lacus Quadrangle (MC-5). The northern area contains relatively smooth plains; the central area, mesas and buttes; and the southern area, numerous craters.]]

The '''Ismenius Lacus quadrangle''' is one of a series of [[list of quadrangles on Mars|30 quadrangle maps of Mars]] used by the [[United States Geological Survey]] (USGS) [[Astrogeology Research Program]]. The [[Quadrangle (geography)|quadrangle]] is located in the northwestern portion of Mars' eastern hemisphere and covers 0° to 60° east longitude (300° to 360° west longitude) and 30° to 65° north latitude. The quadrangle uses a [[Lambert conformal conic projection]] at a nominal scale of 1:5,000,000 (1:5M). The Ismenius Lacus quadrangle is also referred to as MC-5 (Mars Chart-5).<ref>Davies, M.E.; Batson, R.M.; Wu, S.S.C. "Geodesy and Cartography" in Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; Matthews, M.S., Eds. ''Mars''. University of Arizona Press: Tucson, 1992.</ref> The southern and northern borders of the Ismenius Lacus quadrangle are approximately {{convert|3065|km|mi|abbr=on}} and {{convert|1500|km|mi|abbr=on}} wide, respectively. The north-to-south distance is about {{convert|2050|km|mi|abbr=on}} (slightly less than the length of Greenland).<ref>Distances calculated using NASA World Wind measuring tool. http://worldwind.arc.nasa.gov/ {{Webarchive|url=https://web.archive.org/web/20180106075159/http://worldwind.arc.nasa.gov/ |date=2018-01-06 }}.</ref> The quadrangle covers an approximate area of 4.9 million square km, or a little over 3% of Mars' surface area.<ref>Approximated by integrating latitudinal strips with area of R^2 (L1-L2)(cos(A)dA) from 30° to 65° latitude; where R = 3889&nbsp;km, A is latitude, and angles expressed in radians. See: https://stackoverflow.com/questions/1340223/calculating-area-enclosed-by-arbitrary-polygon-on-earths-surface.</ref> The Ismenius Lacus quadrangle contains parts of [[Acidalia Planitia]], [[Arabia Terra]], [[Vastitas Borealis]], and [[Terra Sabaea]].<ref>{{Cite web|url=https://planetarynames.wr.usgs.gov/SearchResults?target=MARS&featureType=Terra,%20terrae|title=Planetary Names: Search Results}}</ref>

The Ismenius Lacus quadrangle contains [[Deuteronilus Mensae]] and [[Protonilus Mensae]], two places that are of special interest to scientists. They contain 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 name="ReferenceA">{{cite journal | last1=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 | journal=Science | volume=328 | issue=5986| pages=1682–1686 | doi=10.1126/science.1189013| pmid=20576889 | bibcode=2010Sci...328.1682C | s2cid=7337256 }}</ref><ref name="jpl.nasa.gov">http://www.jpl.nasa.gov/news.cfm?release=2010-209{{dead link|date=November 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

==Origin of names== {{Main|Classical albedo features on Mars|Planetary nomenclature#Mars}} [[File:Kadmos dragon Louvre N3157.jpg|thumb|200px|[[Cadmus]] slaying the dragon of the Ismenian Spring]] Ismenius Lacus is the name of a [[classical albedo features on Mars|telescopic albedo feature]] located at 40° N and 30° E on Mars. The term is Latin for Ismenian Lake, and refers to the Ismenian Spring near [[Thebes, Greece|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. https://planetarynames.wr.usgs.gov/.</ref>

There appeared to be a large canal in this region 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>

==Physiography and geology== In eastern Ismenius Lacus, lies [[Mamers Valles]], a giant outflow channel. 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.<ref>{{cite web | url=http://www.uahirise.org/ESP_039997_2170 | title=HiRISE &#124; A Fresh, Shallow Valley in Northern Arabia Terra (ESP_039997_2170) }}</ref>

== Lyot Crater == The northern plains 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.<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>{{Cite web|url=http://space.com/scienceastronomy/090514--mars-rivers.html|title=Mars: What We Know About the Red Planet|website=[[Space.com]]|date=October 2021}}</ref> One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and [[Martian dust devils|dust devil tracks]]. Dust devils, which resemble miniature tornados create the tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. Light-toned deposits 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.<ref name="ReferenceA" /><ref name="jpl.nasa.gov" />

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. One evidence for this idea is that there are few secondary craters nearby. Few secondary craters were formed because most landed on ice and did not affect the ground below. The ice accumulated in the area when the climate was different. The tilt or [[obliquity]] of the axis changes frequently. During periods of greater tilt, ice from the poles is redistributed to the mid-latitudes. The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean, these features have been dated to the [[Noachian]] and [[Hesperian]] periods—4 to 3 billion years ago.<ref>{{cite journal|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.| bibcode=2017GeoRL..44.5336W | year=2017 | s2cid=27711077 }}</ref><ref>{{cite journal | last1=Weiss | first1=D. | display-authors=etal | year=2017 | title=Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation | journal=Geophysical Research Letters | volume=44| issue=11 | pages=5336–5344| doi=10.1002/2017GL073821 | bibcode=2017GeoRL..44.5336W | s2cid=27711077 }}</ref><ref>{{Cite web|url=http://spaceref.com/mars/hot-rocks-led-to-relatively-recent-water-carved-valleys-on-mars.html|title=Hot Rocks Led to Relatively Recent Water-Carved Valleys on Mars - SpaceRef|date=14 June 2017}}{{Dead link|date=September 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

==Other craters== [[File:ESP 057007 2190freshcrater.jpg|thumb|upright=1.2|Fresh crater, as seen by HiRISE under HiWish program.]] [[Impact crater]]s generally have a rim with ejecta around them; in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10&nbsp;km in diameter), they usually have a central peak.<ref>{{Cite web|url=http://www.lpi.usra.edu/publications/slidesets/stones/|title=Stones, Wind, and Ice: A Guide to Martian Impact Craters}}</ref> The peak is caused by a rebound of the crater floor following the impact.<ref name="Kieffer1992">{{cite book|author=Hugh H. Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ|access-date=7 March 2011|date=1992|publisher=University of Arizona Press|isbn=978-0-8165-1257-7}}</ref> 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.

== 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&nbsp;km high. Channels in the area have wide, flat floors and steep walls. Many [[butte]]s and [[mesa]]s 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]]s.<ref>{{Cite web | title=Observations of Aprons in Martian fretted terrain | author1=M. C. Malin | author2=K. S. Edgett | url=http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1053.pdf | archive-url=https://web.archive.org/web/20030421125153/http://www.lpi.usra.edu/meetings/lpsc2000/pdf/1053.pdf | archive-date=2003-04-21 | access-date=2009-11-05 | url-status=live }}</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 name="Plaut, J. 2008">Plaut, J. et al. 2008. "Radar Evidence for Ice in Lobate Debris Aprons in the Mid-Northern Latitudes of Mars". ''Lunar and Planetary Science'' XXXIX. 2290.pdf</ref><ref>{{cite journal | last1=Plaut | first1=J. | last2=Safaeinili | first2=A. | last3=Holt | first3=J. | last4=Phillips | first4=R. | last5=Head | first5=J. | last6=Seu | first6=R. | last7=Putzig | first7=N. | last8=Frigeri | first8=A. | year=2009 | title=Radar evidence for ice in lobate debris aprons in the midnorthern latitudes of Mars | journal=Geophys. Res. Lett. | volume=36| issue=2| article-number=2008GL036379 | pages=n/a | doi=10.1029/2008GL036379 | bibcode=2009GeoRL..36.2203P| s2cid=17530607 | doi-access=free }}</ref>

== Glaciers == {{main|Glaciers on Mars}} Glaciers formed much of the observable surface in large areas of Mars. Some look just like alpine glaciers on Earth.<ref>{{cite web | title=HiRISE &#124; HiPOD: 2 Jun 2025 | url=https://www.uahirise.org/hipod/PSP_008809_2215 }}</ref><ref>{{cite web | title=HiRISE &#124; HiPOD: 1 May 2023 | url=https://www.uahirise.org/hipod/ESP_077592_2225 }}</ref> Much of the area in high latitudes, especially the Ismenius Lacus quadrangle, is believed to still contain enormous amounts of water ice.<ref name="Kieffer1992" /><ref name="Plaut, J. 2008" /><ref>{{Cite web|url=https://www.esa.int/|title=European Space Agency|website=www.esa.int}}</ref> 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.<ref>http://news.discovery.com/space/mars-ice-sheet-climate.html {{Dead link|date=March 2022}}</ref> The ice was probably deposited as snowfall during an earlier climate when the poles were tilted more.<ref>Madeleine, J. et al. 2007. "Exploring the northern mid-latitude glaciation with a general circulation model". In: ''Seventh International Conference on Mars''. Abstract 3096.</ref>

Analysis of [[SHARAD]] data led researchers to conclude that martian glaciers are 80% pure ice. The paper authors examined five different sites and all showed high levels of pure water ice.<ref> Yuval Steinberg et al, "Physical properties of subsurface water ice deposits in Mars's Mid-Latitudes from the shallow radar.", Icarus (2025)</ref><ref> https://www.space.com/astronomy/mars/good-news-for-mars-settlers-red-planet-glaciers-are-mostly-pure-water-ice-study-suggests</ref><ref>{{Cite web | title=Mars Glaciers: Pure Water Ice Discovered on the Red Planet! - YouTube | url=https://www.youtube.com/watch?v=nzh2sirXfD8 | access-date=2026-01-17 | website=www.youtube.com}}</ref>

Because of the high purity of the ice content that was found, the authors argued that the formation of glaciers happened by atmospheric precipitation or direct condensation. After glaciers were formed there was a time when enhanced sublimation formed a lag layer or promoted the accumulation of dry debris atop the water ice glacier. Those dry debris would then insulate the underlying ice from going away.<ref> Steinberg, Y. et al. 2025. Physical properties of subsurface water ice deposits in Mars’s Mid-Latitudes from the shallow radar. Icarus. vol. 441 116716</ref>

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.<ref>{{Cite web|url=https://www.uahirise.org/ESP_018857_2225|title=HiRISE &#124; Glacier? (ESP_018857_2225)|website=www.uahirise.org}}</ref> 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.<ref>{{cite web | url=http://hirise.lpl.arizona.edu/PSP_009719_2230 | title=HiRISE &#124; Fretted Terrain Valley Traverse (PSP_009719_2230) }}</ref> 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 [[moraine]]s. Some places on Mars have groups of ridges that are twisted around; this may have been due to more movement after the ridges were put into place. Sometimes chunks of ice fall from the glacier and get buried in the land surface. When they melt, a more or less round hole remains.<ref>{{Cite web|url=https://hirise.lpl.arizona.edu/PSP_006278_2225|title=HiRISE &#124; Jumbled Flow Patterns (PSP_006278_2225)|website=hirise.lpl.arizona.edu}}</ref> On Earth we call these features kettles or kettle holes. [[Mendon Ponds Park]] in upstate New York has preserved several of these kettles. The picture from [[HiRISE]] below shows possible kettles in Moreux Crater.

==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<ref>{{cite journal | last1=Touma | first1=J. | last2=Wisdom | first2=J. | year=1993 | title=The Chaotic Obliquity of Mars | journal=Science | volume=259 | issue=5099| pages=1294–1297 | doi=10.1126/science.259.5099.1294| pmid=17732249 | bibcode=1993Sci...259.1294T | s2cid=42933021 | hdl=1721.1/129962 | hdl-access=free }}</ref><ref name="ReferenceC">{{cite journal | last1=Laskar | first1=J. | last2=Correia | first2=A. | last3=Gastineau | first3=M. | last4=Joutel | first4=F. | last5=Levrard | first5=B. | last6=Robutel | first6=P. | year=2004 | title=Long term evolution and chaotic diffusion of the insolation quantities of Mars | journal=Icarus | volume=170 | issue=2| pages=343–364 | doi=10.1016/j.icarus.2004.04.005 | bibcode=2004Icar..170..343L| s2cid=33657806 | url=https://hal.archives-ouvertes.fr/hal-00000860/file/Ma_2004.laskar_prep.pdf }}</ref> 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.<ref>{{cite journal | last1=Levy | first1=J. | last2=Head | first2=J. | last3=Marchant | first3=D. | last4=Kowalewski | first4=D. | year=2008 | title=Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix landing site: Implications for substrate properties and climate-driven morphological evolution | journal=Geophys. Res. Lett. | volume=35| issue=4| pages=L04202 | doi=10.1029/2007GL032813 | bibcode=2008GeoRL..35.4202L| doi-access=free }}</ref> 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.<ref>{{cite journal | last1=Levy | first1=J. | last2=Head | first2=J. | last3=Marchant | first3=D. | year=2009a | title=Thermal contraction crack polygons on Mars: Classification, distribution, and climate implications from HiRISE observations | journal=J. Geophys. Res. | volume=114| issue=E1| pages=E01007 | doi=10.1029/2008JE003273 | bibcode=2009JGRE..114.1007L| doi-access=free }}</ref><ref>Hauber, E., D. Reiss, M. Ulrich, F. Preusker, F. Trauthan, M. Zanetti, H. Hiesinger, R. Jaumann, L. Johansson, A. Johnsson, S. Van Gaselt, M. Olvmo. 2011. Landscape evolution in Martian mid-latitude regions: insights from analogous periglacial landforms in Svalbard. In: Balme, M., A. Bargery, C. Gallagher, S. Guta (eds). ''Martian Geomorphology''. Geological Society, London. Special Publications: 356. 111–131</ref> General circulation models of the Martian atmosphere predict accumulations of ice-rich dust in the same areas where ice-rich features are found.<ref name="ReferenceC" /> When the tilt begins to return to lower values, the ice sublimates (turns directly to a gas) and leaves behind a lag of dust.<ref name="Mellon, M. 1995">{{cite journal | last1=Mellon | first1=M. | last2=Jakosky | first2=B. | year=1995 | title=The distribution and behavior of Martian ground ice during past and present epochs | journal=J. Geophys. Res. | volume=100 | issue=E6| pages=11781–11799 | doi=10.1029/95je01027 | bibcode=1995JGR...10011781M| s2cid=129106439 }}</ref><ref>{{cite journal | last1=Schorghofer | first1=N | year=2007 | title=Dynamics of ice ages on Mars | journal=Nature | volume=449 | issue=7159| pages=192–194 | doi=10.1038/nature06082| pmid=17851518 | bibcode=2007Natur.449..192S| s2cid=4415456 }}</ref> The lag deposit caps the underlying material so with each cycle of high tilt levels, some ice-rich mantle remains behind.<ref>Madeleine, J., F. Forget, J. Head, B. Levrard, F. Montmessin. 2007. "Exploring the northern mid-latitude glaciation with a general circulation model". In: ''Seventh International Conference on Mars''. Abstract 3096.</ref> Note that the smooth surface mantle layer probably represents only relative recent material.

== Pits and cracks == [[File:CTX Context Image of Pits.JPG|thumb|upright=1.2|CTX Image in [[Protonilus Mensae]], showing location of next image]] 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.<ref>{{cite web|url=http://hirise.lpl.arizona.edu/PSP_009719_2230 |title=HiRISE &#124; Fretted Terrain Valley Traverse (PSP_009719_2230) |publisher=Hirise.lpl.arizona.edu |access-date=December 19, 2010}}</ref>

==Ocean== Many researchers have suggested that Mars once had a great ocean in the north.<ref>{{cite journal | last1=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 | journal=J. Geophys. Res. | volume=98 | issue=E6| pages=11061–11078 | doi=10.1029/93je00618 | bibcode=1993JGR....9811061P}}</ref><ref>{{cite journal | last1=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 | doi=10.1016/s0019-1035(03)00144-1 | bibcode=2003Icar..165...53F | access-date=2018-11-04 | archive-date=2020-12-10 | archive-url=https://web.archive.org/web/20201210084719/http://eprints.ucm.es/10431/1/9-Marte_3.pdf | url-status=dead }}</ref><ref>{{cite journal | last1=Head | first1=J. W. |display-authors=etal | year=1999 | title=Possible ancient oceans on Mars: Evidence from Mars Orbiter Laser Altimeter data | journal=Science | volume=286 | issue=5447| pages=2134–2137 | doi=10.1126/science.286.5447.2134| pmid=10591640 | bibcode=1999Sci...286.2134H }}</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>{{cite journal | last1=Carr | first1=M. H. | last2=Head | first2=J. W. | year=2003 | title=Oceans on Mars: An assessment of the observational evidence and possible fate | journal=J. Geophys. Res. | volume=108 | issue=E5| page=5042 | doi=10.1029/2002JE001963 | bibcode=2003JGRE..108.5042C| doi-access=free }}</ref><ref>{{cite journal | last1=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 | journal=J. Geophys. Res. | volume=107 | issue=E12| page=5121 | doi=10.1029/2001JE001831 | bibcode=2002JGRE..107.5121K| doi-access=free }}</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 [[tsunami]]s. The tsunamis were caused by asteroids striking the ocean. Both were thought to have been strong enough to create 30&nbsp;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. Numerical simulations show that in this particular part of the ocean two impact craters of the size of 30&nbsp;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>{{Cite press release |title=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>{{cite journal | last1=Rodriguez | first1=J. |display-authors=etal | year=2016 | title=Tsunami waves extensively resurfaced the shorelines of an early Martian ocean | journal=Scientific Reports | volume=6 | article-number=25106 | doi=10.1038/srep25106| pmid=27196957 | pmc=4872529 | bibcode=2016NatSR...625106R }}</ref><ref>{{Cite journal | 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| article-number=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| bibcode=2016NatSR...625106R}}</ref><ref>Cornell University. "Ancient tsunami evidence on Mars reveals life potential." ''ScienceDaily'', 19 May 2016. https://www.sciencedaily.com/releases/2016/05/160519101756.htm.</ref> {{Main|Mars ocean hypothesis}}

== See also == {{div col|colwidth=30em}} * [[Climate of Mars]] * [[Deuteronilus Mensae]] * [[Dunes]] * [[Fretted terrain]] * [[Glacier]] * [[Glaciers on Mars]] * [[Gully (Mars)]] * [[HiRISE]] * [[Impact crater]] * [[List of quadrangles on Mars]] * [[Lobate debris apron]] * [[Lyot Crater]] * [[Polygonal patterned ground]] * [[Protonilus Mensae]] * [[Ring mold crater]] * [[Upper Plains Unit]] * [[Vallis (planetary geology)|Vallis]] * [[Water on Mars]] {{div col end}}

== References == {{Reflist|30em}}

== External links == {{commons category|Ismenius Lacus quadrangle}}

* [https://www.youtube.com/watch?v=_sUUKcZaTgA Martian Ice – Jim Secosky – 16th Annual International Mars Society Convention] * [https://www.youtube.com/watch?v=kpnTh3qlObk T. Gordon Wasilewski - Water on Mars - 20th Annual International Mars Society Convention] Describes how to get water from ice in the ground * [https://www.youtube.com/watch?v=m2ERsEXAq_s Jeffrey Plaut - Subsurface Ice - 21st Annual International Mars Society Convention-2018]

{{Mars quadrangle layout}} {{Mars}} {{Portal bar|Solar System}}

{{DEFAULTSORT:Ismenius Lacus Quadrangle}} [[Category:Ismenius Lacus quadrangle| ]] [[Category:Mars]]