Linear ridge networks are found in various places on Mars in and around craters. These features have also been called "polygonal ridge networks", "boxwork ridges", and "reticulate ridges". Ridges often appear as mostly straight segments that intersect in a lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind. It is reasonable to think that on Mars impacts broke the ground with cracks since faults are often formed in impact craters on Earth. One could guess that these ridge networks were dikes, but dikes would go more or less in the same direction, as compared to these ridges that have a large variety of orientations. Since the ridges occur in locations with clay, these formations could serve as a marker for clay which requires water for its formation. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life. These ridges could be formed by large impacts that produced fractures, faults, or dikes made up of melted rock and/or crushed rock (

breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...

). One formation mechanism proposed by Quinn and Ehlmann in 2017 was that sediment was deposited and eventually the sediment underwent

diagenesis Diagenesis () is the process of physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition. Increased pressure and temperature only start to play a role as sedi ...

which caused a loss of volume and fractures. After erosion exposed the fractures, they were filled with minerals possibly by acid-sulfate fluids. More erosion removed softer materials and left the more resistant ridges behind. If the impact-caused dike is made of purely melted rock from the heat of the impact, it is called a

pseudotachylite Pseudotachylyte (sometimes written as pseudotachylite) is an extremely fine-grained to glassy, dark, cohesive rock occurring as veinsTrouw, R.A.J., C.W. Passchier, and D.J. Wiersma (2010) ''Atlas of Mylonites- and related microstructures.'' Spring ...

. Also, hydrothermalism may have been involved due to the heat generated during impacts. Strong evidence for hydrothermalism was reported by a team of researchers studying Auki Crater. This crater contains ridges that may have been produced after fractures formed with an impact. Using instruments on the

Mars Reconnaissance Orbiter The ''Mars Reconnaissance Orbiter'' (''MRO'') is a spacecraft designed to search for the existence of water on Mars and provide support for missions to Mars, as part of NASA's Mars Exploration Program. It was launched from Cape Canaveral on Au ...

they found the minerals

smectite A smectite (; ; ) is a mineral mixture of various swelling sheet silicates (phyllosilicates), which have a three-layer 2:1 (TOT) structure and belong to the clay minerals. Smectites mainly consist of montmorillonite, but can often contain secon ...

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

zeolite Zeolites are a group of several microporous, crystalline aluminosilicate minerals commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a meta ...

, serpentine,

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

, and chlorite that are common in impact-induced hydrothermal systems on Earth. Other evidence of post-impact hydrothermal systems on Mars from other scientists who studied other Martian craters. Because ridges seem to be found in older crust only, it is believed that they occurred early in the history of Mars when there were more and larger asteroids striking the planet. These early impacts may have caused the early crust to be full of interconnected channels. These networks have been found many regions of Mars including in

Arabia Terra Arabia Terra is a large upland region in the north of Mars that lies mostly in the Arabia quadrangle, but a small part is in the Mare Acidalium quadrangle. It is densely cratered and heavily eroded. This battered topography indicates great age ...

(

Arabia quadrangle The Arabia 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 Arabia quadrangle (geography), quadrangle is also referred ...

), northern

Meridiani Planum Meridiani Planum (alternatively Terra Meridiani) is a large plain straddling the equator of Mars. The plain sits on top of an enormous body of sediments that contains bound water. The iron oxide in the spherules is crystalline (grey) hematite (Fe ...

, Solis Planum,

Noachis Terra Noachis Terra (; lit. "Land of Noah") is an extensive southern landmass (''terra'') of the planet Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a deser ...

(

Noachis quadrangle The Noachis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Noachis quadrangle is also referred to as MC-27 (Mars Chart-27). The Noachis quadrangl ...

Atlantis Chaos Atlantis Chaos is a region of chaos terrain in the Phaethontis quadrangle of Mars. It is located around 34.7° south latitude, and 177.6° west longitude. It is encompassed by the Atlantis basin. The region is across, and was named after an al ...

, and Nepenthes Mensa (

Mare Tyrrhenum quadrangle The Mare Tyrrhenum 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. This quadrangle (geography), quadrangle is also referre ...

). A somewhat different ridge formation has been discovered in the Eastern

Medusae Fossae Formation The Medusae Fossae Formation is a large geological formation of probable volcanic origin on the planet Mars. It is named for the Medusa of Greek mythology. "Fossae" is Latin for "trenches". The formation is a collection of soft, easily eroded de ...

; these dark ridges can be 50 meters in height and erode into dark boulders. It has been suggested that there are from lava filling fractures in the Medusae Fossae Formation which is surrounded by lava flows. Kerber, L., et al. 2017. Polygonal ridge networks on Mars: Diversity of morphologies and the special case of the Eastern Medusae Fossae Formation. Icarus: 281, 200-219.

Linear ridge networks in
Mare Tyrrhenum quadrangle The Mare Tyrrhenum 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. This quadrangle (geography), quadrangle is also referre ...

Some of these may be from hydrothermal systems produced after an impact. ESP 036893 1765ridgesnepenthestop.jpg, Linear ridge network, as seen by HiRISE under HiWish program ESP 045992 1780ridges.jpg, Wide view of several groups of linear ridges, as seen by HiRISE under HiWish program 45992 1780curvedridges.jpg, Close view of curved ridges, as seen by HiRISE under HiWish program. Note: this is an enlargement of previous image. 45992 1780ridgeswide.jpg, Close view of ridges, from a previous image, as seen by HiRISE under HiWish program 45992 1780blocks.jpg, Close view of ridges, from a previous image, as seen by HiRISE under HiWish program. Arrows indicate fractures in ridge 45992 1780roughblocks.jpg, Blocks probably formed after fracturing in ridges, as seen by HiRISE under HiWish program

Linear ridge networks in
Casius quadrangle The Casius quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The quadrangle is located in the north-central portion of Mars' eastern hemisphere and cov ...

ESP 043845 2130ridges.jpg, Network of ridges, as seen by HiRISE under

HiWish program HiWish is a program created by NASA so that anyone can suggest a place for the HiRISE camera on the Mars Reconnaissance Orbiter to photograph. It was started in January 2010. In the first few months of the program 3000 people signed up to use HiR ...

. Ridges may be formed in various ways. ESP 043845 2130ridgesclose.jpg, Color, close-up of ridges seen in previous image, as seen by HiRISE under HiWish program ESP 043845 2130ridgeswide.jpg, More ridges from the same place as the previous two images, as seen by HiRISE under HiWish program ESP 036869 2105ridgeswide.jpg, Linear ridge network, as seen by HiRISE under HiWish program ESP 036869 2105ridgesclose.jpg, Close-up and color image of previous image of linear ridge network, as seen by HiRISe under HiWish program ESP 036869 2105ridgesbottom.jpg, More linear ridge networks from same location as previous two images, as seen by HiRISE under HiWish program ESP 048236 2105ridgeswide.jpg, Wide view of network of ridges, as seen by HiRISE under HiWish program. Portions of this image are enlarged in following images. 48236 2105ridges3.jpg, Close view of network of ridges, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. 48236 2105ridges2.jpg, Close view of network of ridges, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. Box shows the size of a football field. 48236 2105ridges.jpg, Close view of network of ridges, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. 48236 2105ridgesmesa.jpg, Close view of ridges, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. A small mesa in the image displays layers. ESP 048236 2105ridgesclosecolor.jpg, Close, color view of network of ridges, as seen by HiRISE under HiWish program. This is an enlargement of a previous image.

Linear ridge networks in
Syrtis Major quadrangle The Syrtis Major quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Syrtis Major quadrangle is also referred to as MC-13 (Mars Chart-13). The quadra ...

Image:Huo Hsing Vallis in Syrtis Major.JPG, Huo Hsing Vallis in Syrtis Major, as seen by THEMIS. Straight ridges may be

dikes Dyke or dike may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), formations of magma or sediment that cut through and across the layering of adjacent rocks * Dike (mythology), ''Dikē'', the Greek goddess ...

in which liquid rock once flowed. Image:Huo Hsing Vallis Ridges.JPG, Huo Hsing Vallis Ridges, as seen by

HiRISE High Resolution Imaging Science Experiment is a camera on board the '' Mars Reconnaissance Orbiter'' which has been orbiting and studying Mars since 2006. The 65 kg (143 lb), US$40 million instrument was built under the direction ...

. Ridges may be caused by water moving along faults. ESP 043410 1980ridges.jpg, Ridges, as seen by HiRISE under HiWish program. These may be the result of dikes or faults.

Linear ridge networks in
Phaethontis quadrangle The Phaethontis 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 Phaethontis quadrangle (geography), quadrangle is also ...

ESP 034887 1490ridgesphaethontis.jpg, Linear ridge networks, as seen by HiRISE under HiWish program ESP 034887 1490ridgesphaethontisclose.jpg, Close-up of linear ridge networks from the previous image, as seen by HiRISE under HiWish program ESP 036443 1495ridgesphaethontistop.jpg, Linear ridge networks, as seen by HiRISE under HiWish program ESP 036443 1495ridgesphaethontisbottom.jpg, Linear ridge networks, as seen by HiRISE under HiWish program

Linear ridge networks in
Amazonis quadrangle The Amazonis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Amazonis quadrangle is also referred to as MC-8 (Mars Chart-8). The quadrangle cove ...

Image:26552sharpridges.jpg, Narrow ridges, as seen by HiRISE under HiWish program. The ridges may be the result of impacts fracturing the surface. ESP 036745 1905top.jpg, Linear ridge networks, as seen by HiRISE under HiWish program 36745 1905lridgesshort.jpg, Close-up of ridge network, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. 36745 1905ridgesx.jpg, Close-up of ridge network, as seen by HiRISE under HiWish program. This is an enlargement of a previous image. ESP 036745 1905ridges.jpg, Linear ridge networks, as seen by HiRISE under HiWish program

Linear ridge networks in
Arabia quadrangle The Arabia 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 Arabia quadrangle (geography), quadrangle is also referred ...

ESP 036316 2015straightridges.jpg, Linear ridge network, as seen by HiRISE under HiWish program. Dark line is not part of the picture. Image:ESP_020230dikes.jpg, Dikes in Arabia, as seen by HiRISE, under the HiWish program. These straight features may indicate where valuable ore deposits may be found by future colonists. Scale bar is 500 meters. They may be part of linear ridges, hence related to impact craters. Image:Ridgecomplex22919.jpg, Close-up of a complex group of ridges. The ridges may be the remains of old streams and/or linear ridge networks. Image taken by HiRISE under the HiWish program.

Linear ridge networks in
Arcadia quadrangle The Arcadia 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 nort ...

ESP 047054 2160ridges.jpg, Wide view of ridge network, as seen by HiRISE under HiWish program 47054 2160largeridges.jpg, Close view of ridge networks, as seen by HiRISE under HiWish program. Arrow points to small, straight ridge. 47054 2160largeridgeschanging.jpg, Close view of small and large ridges, as seen by HiRISE under HiWish program 47054 2160smallridges.jpg, Close view of small and large ridges, as seen by HiRISE under HiWish program File:Ridges in ESP 074906 2160.jpg, Ridges. This picture was named HiRISE picture of the day on March 29, 2024. File:ESP 074906 2160-2ridgesclose.jpg, Close view of ridges. This picture was named HiRISE picture of the day on March 29, 2024.

References

{{Reflist, 30em

External links

Zooniverse - Project - Planet four ridges
: help scientists exploring Mars by discovering networks of polygonal ridges * Kerber, L., et al. 2017. Polygonal ridge networks on Mars: Diversity of morphologies and the special case of the Eastern Medusae Fossae Formation. Icarus. Volume 281. Pages 200-219 Geology of Mars

Linear ridge networks in Casius quadrangle The Casius quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The quadrangle is located in the north-central portion of Mars' eastern hemisphere and cov ...

Linear ridge networks in Syrtis Major quadrangle The Syrtis Major quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Syrtis Major quadrangle is also referred to as MC-13 (Mars Chart-13). The quadra ...

Linear ridge networks in Phaethontis quadrangle The Phaethontis 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 Phaethontis quadrangle (geography), quadrangle is also ...

Linear ridge networks in Amazonis quadrangle The Amazonis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Amazonis quadrangle is also referred to as MC-8 (Mars Chart-8). The quadrangle cove ...

Linear ridge networks in Arabia quadrangle The Arabia 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 Arabia quadrangle (geography), quadrangle is also referred ...

Linear ridge networks in Arcadia quadrangle The Arcadia 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 nort ...

See also