Tartarus Colles based on THEMIS day-time image Tartarus Colles are a group of knobby hills in the northern plains of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

Context

Tartarus Colles runs from 8° to 33° north latitude and 170° to 200° west longitude. They were named after a classic albedo feature. The name was officially approved by the IAU in 1985. The term " Colles" is used for small hills or knobs. There are over 40,000 knobs associated with Tartarus Colles. This landform is located within the

Diacria quadrangle The Diacria 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 northwestern portion of Mars’ western hemisphere and co ...

Geology

Some researchers have proposed that the knobs of western Tartarus Colles are consistent with concurrent interpretations of knobs in Cerberus Palus (downstream of

Athabasca Valles The Athabasca Valles are a late Amazonian-period outflow channel system in the central Elysium Planitia region of Mars, located to the south of the Elysium Rise. They are part of a network of outflow channels in this region that are understood ...

), which would suggest that they formed as the result of interactions between lava and water to form what has been termed by some authors as volcanic rootless constructs (VRC). This class of lava-water interactions includes

rootless cone A rootless cone, also formerly called a pseudocrater, is a volcano, volcanic landform which resembles a true volcanic crater, but differs in that it is not an actual vent from which lava has erupted. They are characterised by the absence of any ma ...

s, but have fewer genetic implications in their definition, as are not necessarily

phreatomagmatic Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions cont ...

(resulting from the explosion of steam from the sudden evaporation of fluids on contact with lava). The water source is not required to have been added ''en masse'' in the form of some aqueous flood - instead possibly being available in the form of an extremely thin and shallow ground ice reservoir whose presence and extent is controlled by

obliquity In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbit ...

as an orbital forcer.

Observational history

In 2008, Mark A. Bishop of the

Planetary Science Institute The Planetary Science Institute (PSI) is a 501(c)(3) non-profit research institute based in Tucson, Arizona, focusing on planetary science. , its director is Dr. Mark V. Sykes. PSI, along with Space Science Institute (SSI) Southwest Researc ...

and the

University of South Australia The University of South Australia (UniSA) is a public research university in the Australian state of South Australia. It is a founding member of the Australian Technology Network of universities, and is the largest university in South Australi ...

reported on his results using higher-order neighbor analysis to attempt to discern any kind of pattern in the distribution of Tartarus Colles' knobs. The purpose of the study was to reconcile competing hypotheses as to the origin of these knobby landforms, which had been analogized by other authors to putative

pingo Pingos are intrapermafrost ice-cored hills, high and in diameter. They are typically conical in shape and grow and persist only in permafrost environments, such as the Arctic and subarctic. A pingo is a periglacial landform, which is define ...

es and

s in

and elsewhere in

Elysium Planitia Elysium Planitia, located in the Elysium and Aeolis quadrangles, is a broad plain that straddles the equator of Mars, centered at . It lies to the south of the volcanic province of Elysium, the second largest volcanic region on the planet, a ...

. Bishop found the cones of Tartarus Colles to exhibit a

complete spatial randomness Complete spatial randomness (CSR) describes a point process whereby point events occur within a given study area in a completely random fashion. It is synonymous with a ''homogeneous spatial Poisson process''.O. Maimon, L. Rokach, ''Data Mining and ...

except where

solifluction Solifluction is a collective name for gradual processes in which a mass moves down a slope ("mass wasting") related to freeze-thaw activity. This is the standard modern meaning of solifluction, which differs from the original meaning given to it ...

or magmatic effects were readily apparent. In 2011, Christopher W. Hamilton and Sarah A. Fagents of the

University of Hawaiʻi at Mānoa The University of Hawaii at Mānoa (University of Hawaii—Mānoa, UH Mānoa, Hawai'i, or simply UH) is a Public university, public Land-grant university, land-grant research university in Manoa, Mānoa, a neighborhood in Honolulu, Hawaii. It ...

Honolulu Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the island ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, and Thorvaldur Thordarson of the

University of Edinburgh The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 15 ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

reported on the results of their geomorphic mapping, lava thickness estimations, and statistical analyses ( nearest neighbor modeling) to investigate the hypotheses that the cones of Tartarus Colles are what the authors have termed "volcanic rootless constructs" - a more generalized variation of the term "

" that does not explicitly require a phreatomagmatic origin, or any clear explosive expression such as a pseudocrater. The authors criticize the tendency to generalize Martian pseudocrater analogies against

Mývatn () is a shallow lake situated in an area of active volcanism in the north of Iceland, not far from Krafla volcano. It has a high amount of biological activity. The lake and the surrounding wetlands provides a habitat for a number of waterbirds, e ...

, the Icelandic lake, which has been used as a type example of structures arising on Mars from water-lava interactions in a way that ignores the variability of such structures even across Iceland.

Gallery

Image:Tartarus Colles.JPG, Tartarus Colles as seen by

THEMIS In Greek mythology and Ancient Greek religion, religion, Themis (; grc, Θέμις, Themis, justice, law, custom) is one of the twelve Titans, Titan children of Gaia and Uranus (mythology), Uranus, and the second wife of Zeus. She is the godde ...

. Click on image to see

dark slope streaks Dark slope streaks are narrow, avalanche-like features common on dust-covered slopes in the equatorial regions of Mars.Chuang, F.C.; Beyer, R.A.; Bridges, N.T. (2010). Modification of Martian Slope Streaks by Eolian Processes. ''Icarus,'' 205 154 ...

Image:Tartarus Colles Channel.JPG, Tartarus Colles channel, 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 o ...

. Scale bar is 500 meters. Click on image to see bridge across channel.

References

Diacria quadrangle Hills on Mars {{Mars-stub