Outflow channels
Outflow channels are extremely long, wide swathes of scoured ground on Mars.[1] They extend many hundreds of kilometers in length and are typically greater than one kilometer in width. They are thought to have been carved by huge outburst floods.
The outflow channels contrast with the Martian channel features known as "
Outflow channels tend to be named after the names for Mars in various ancient world languages, or more rarely for major terrestrial rivers.[4] The term outflow channels was introduced in planetology in 1975.[5]
Formation
On the basis of their geomorphology, locations and sources, the channels are today generally thought to have been carved by
List of outflow channels by region
This is a partial list of named channel structures on Mars claimed as outflow channels in the literature, largely following The Surface of Mars by Carr. The channels tend to cluster in certain regions on the Martian surface, often associated with volcanic provinces, and the list reflects this. Originating structures at the head of the channels, if clear and named, are noted in parentheses and in italics after each entry.
Circum-Chryse region
Chryse Planitia is a roughly circular volcanic plain east of the Tharsis bulge and its associated volcanic systems. This region contains the most prominent and numerous outflow channels on Mars. The channels flow east or north into the plain.
- Ares Vallis (Aram Chaos; Iani Chaos)
- Kasei Vallis (Echus Chasma)
- Maja Valles (Juventae Chasma)
- Mawrth Vallis (no obvious source)
- Ravi Vallis (Aromatum Chaos)
- Orson Welles crater; Ganges Chasma?)
- Simud Valles (Hydraotes Chaos; Aureum Chaos?; Arsinoes Chaos?)
- Tiu Valles (Aram Chaos?; Aureum Chaos?)
Tharsis region
In this region it is particularly difficult to distinguish outflow channels from lava channels but the following features have been suggested as at least overprinted by outflow channel floods:
- Parts of the Olympica Fossae
- Valleys adjacent to the southeast margin of Olympus Mons (nameless graben)
Amazonis and Elysium Planitiae
Several channels flow either onto the plains of Amazonis and Elysium from the southern highlands, or originate at graben within the plains. This region contains some of the youngest channels.[17] Some of these channels have rare tributaries, and they do not start at a chaos region. It has been suggested the formation mechanisms for these channels may be more variable than for those around Chryse Planitia, perhaps in some cases involving lake breaches at the surface.[18]
- Al-Qahira Vallis
- Athabasca Vallis (Cerberus Fossae)
- Grjota Vallis (nameless graben)
- Ma'adim Vallis(shallow depression in Highlands)
- Mangala Valles (Mangala Fossa)
- Marte Vallis (Cerberus Planitia)
Utopia Planitia
Several outflow channels rise in the region west of the
- Granicus Vallis (graben radial to Elysium Mons)
- Hrad Valles(graben radial to Elysium Mons)
- Tinjar Vallis(graben radial to Elysium Mons)
- Hebrus Valles (irregular depression; ends in discontinuous linear hollows)
- Hephaestus Fossae (irregular depression; flows through angular segments; ends in discontinuous linear hollows)
Hellas region
Three valleys flow from east of its rim down onto the floor of the Hellas basin.
- box canyonnear Hadriaca Patera)
- Harmakhis Vallis (close to end of Reull Vallis)
- Niger Vallis (indistinct depressions near Hadriaca Patera)
Argyre region
It has been argued that Uzboi, Ladon, Margaritifer and Ares Valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia.[21] The source of this outflow has been suggested as overflow from the Argyre crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from the south pole. If real, the full length of this drainage system would be over 8000 km, the longest known drainage path in the solar system. Under this suggestion, the extant form of the outflow channel Ares Vallis would thus be a remolding of a pre-existing structure.
Polar regions
The large troughs present in each pole,
See also
- Chaos terrain – Distinctive area of broken or jumbled terrain
- List of areas of chaos terrain on Mars
- Martian chaos terrain – Irregular groups of large blocks of rock
- Outburst flood – High-magnitude, low-frequency catastrophic flood involving the sudden release of water
- Valley network (Mars)
Further reading
- Baker, V.R.; Carr, M.H.; Gulick, V.C.; Williams, C.R. & Marley, M.S. "Channels and Valley Networks". In Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W. & Matthews, M.S. (eds.). Mars. Tucson, AZ: University of Arizona Press.
- Carr, M.H. (11 January 2007). "Channels, Valleys and Gullies". The Surface of Mars. ISBN 978-0-521-87201-0.
References
- ^ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
- ^ Hartmann, W.K., and Neukum, G. (2001). "Cratering chronology and the evolution of Mars". In: Chronology and Evolution of Mars, ed. R. Kallenbach et al. Dordrecht: Kluwer, p. 165-94.
- ^ Burr, D.M., McEwan, A.S., and Sakimoto, S.E. (2002). "Recent aqueous floods from the Cerberus Fossae", Mars. Geophys. Res. Lett., 29(1), 10.1029/2001G1013345.
- ^ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
- ^ http://www.vanderbilt.edu/AnS/physics/astrocourses/AST101/readings/mars_water.html
- ^ Baker, V.R. (1982). The Channels of Mars. Austin: Texas University Press.
- ^ Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
- ^ Luchitta, B.K. (2001). "Antarctic ice streams and outflow channels on Mars". Geophys. Res. Lett., 28, 403-6.
- .
- ^ Tanaka, K.L. (1999). "Debris flow origin for the Simud/Tiu deposit on Mars". J. Geophys. Res., 104, 8637-52.
- ^ Hoffman, N. (2000). White Mars. Icarus, 146, 326-42.
- ^ Williams, R.M., Phillips, R.J., and Malin, M.C. (2000). "Flow rates and duration within Kasei Vallis, Mars: Implications for the formation of a Martian ocean". Geophys. Res. Lett., 27, 1073-6.
- ^ Robinson, M.S., and Takana, K.L. (1990), "Magnitude of a catastrophic flood event in Kasei Vallis, Mars". Geology, 18, 902-5.
- ^ Baker, V.R. (1982). The Channels of Mars. Austin: Texas University Press.
- ^ Garcia-Castellanos, D., et al., (2009). "Catastrophic flood of the Mediterranean after the Messinian Salinity Crisis". Nature, 462, 778-782.
- ^ Carr,M.H. (1979). "Formation of Martian flood features by release of water from confined aquifers". J. Geophys. Res., 84, 2995-3007.
- ^ Burr, D.M., McEwan, A.S., and Sakimoto, S.E. (2002). "Recent aqueous floods from the Cerberus Fossae, Mars". Geophys. Res. Lett., 29(1), 10.1029/2001G1013345.
- ^ Irwin, R.P., Maxwell, T.A., Craddock, R.A., and Leverington, D.W. (2002). "A large paleolake basin at the head of Ma'adim Vallis, Mars". Science, 296, 2209-12.
- ^ Christiansen, E.H. (1989). "Lahars in the Elysium region of Mars". Geology, 17, 203-6.
- ^ Carr, M.H. (2006), The Surface of Mars. Cambridge Planetary Science Series, Cambridge University Press.
- ^ Parker, T.J., Clifford, S.m., and Banerdt, W.B. (2000). "Argyre Planitia and the Mars global hydrologic cycle". LPSC XXXI, Abstract 2033.
- ^ Clifford, S.M. (1987). "Basal polar melting on Mars". J. Geophys. Res., 92, 9135-52.
- ^ Howard, A.D. (2000). "The role of aeolian processes in forming surface features of the martian polar layered deposits". Icarus, 144, 267-88.