Marte Vallis

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".^[2] It has been identified as an outflow channel, carved in the geological past by catastrophic release of water from aquifers beneath the Martian surface.^[3] The surface material is thought to have been created out of 'a'ā and pāhoehoe lava flows from the Elysium volcanic province in the west.^[4]

Marte Vallis

Marte Vallis based on THEMIS day-time image
Coordinates	15°N 176.5°W / 15; -176.5

Columnar jointing in basalt, Marte Vallis. Image courtesy High Resolution Imaging Science Experiment, University of Arizona.^[1]

Marte Vallis is the site of the first discovery of columnar jointing on Mars.^[1] Columnar jointing often forms when basalt lava cools.^[5]

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  Streamlined Island in Marte Vallis, as seen by HiRISE. The enlarged image gives a good view of dark slope streaks. Island is just to the west of Pettit Crater. Scale bar is 500 meters long.
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  Layers in old crater rim, in Marte Vallis as seen by HiRISE under HiWish program
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  Close view of layers from previous image, as seen by HiRISE under HiWish program Some dark slope streaks are visible.
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  Columinar Jointing in Yellowstone National Park.
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  Columnar jointing in the basalt of the Giant's Causeway in Northern Ireland