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Crater with debris aprons in tyrrhena terra
Tyrrhena Terra is a large area on Mars, centered south of the Martian equator and immediately northeast of the Hellas basin. Its coordinates are 14.8°S 90°E / -14.8; 90, and it covers 2300 km at its broadest extent. It was named for a classic albedo feature of the planet and is in the Mare Tyrrhenum quadrangle of Mars. Tyrrhena Terra is typical of the southern Martian terrae, with heavily cratered highlands and other rugged terrain. It contains the large volcano Tyrrhena Patera, one of the oldest volcanoes on Mars. Its largest crater is Herschel. Licus Vallis and the Ausonia Montes are other major features in the region. Some channels and dunes are visible in Tyrrhena Terra, as shown in the images below.
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Dunes
When there are perfect conditions for producing sand dunes, steady wind in one direction and just enough sand, a barchan sand dune forms. Barchans have a gentle slope on the wind side and a much steeper slope on the lee side where horns or a notch often forms. Some of the dunes in the pictures above are barchans. Barchan is a Russian term because this type of dune was first seen in the desert regions of Turkistan.