Marte Vallis is a valley in the Amazonis quadrangle of Mars, located at 15 North and 176.5 West. It is 185 km long and was named for the Spanish word for "Mars". It has been identified as an

outflow channel Outflow channels are extremely long, wide swathes of scoured ground on Mars. 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. ...

, carved in the geological past by catastrophic release of water from

aquifers An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

beneath the Martian surface. The surface material is thought to have been created out of 'a'ā and

pāhoehoe Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

lava flows from the Elysium volcanic province in the west. Marte Vallis is the site of the first discovery of

columnar jointing Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as joints, result in the formation of a regular array of polygonal prisms, or columns. Columnar jointing occurs in many types of igneo ...

on Mars.Milazzo, M.P., Keszthelyi, L.P., Jaeger, W.L. Rosiek, M., Mattson, S., Verba, C., Beyer, R.A., Geissler, P.E., McEwen, A.S., and the HiRISE Team. (2009) Discovery of columnar jointing on Mars. Geology. 37(2), 171–174
Abstract
/ref> Columnar jointing often forms when basalt lava cools.Bates, R. and J. Jackson (eds.) 1976. Dictionary of Geological Terms. Doubleday, New York. File:Marte Vallis Island.JPG, Streamlined Island in Marte Vallis, 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 ...

. The enlarged image gives a good view of

dark slope streak 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 ...

s. Island is just to the west of Pettit Crater. Scale bar is 500 meters long. ESP 045120 1905layers.jpg, Layers in old crater rim, in Marte Vallis as seen by HiRISE under HiWish program 45120 1905layers.jpg, Close view of layers from previous image, as seen by HiRISE under HiWish program Some

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 ...

are visible. Image:Columnar Jointing in Yellowstone.JPG, Columinar Jointing in

Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowst ...

. Image:Giants-causeway-in-ireland.jpg, Columnar jointing in the basalt of the

Giant's Causeway The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic fissure eruption. It is located in County Antrim on the north coast of Northern Ireland, about three miles (5 km) northeast of ...

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...

References

See also