Angustus Labyrinthus is a complex of intersecting valleys or ridges near the Martian south pole (in the

Mare Australe quadrangle The Mare Australe quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Mare Australe quadrangle is also referred to as MC-30 (Mars Chart-30). The quadr ...

), located at 81.68° S and 63.25° W. It was nicknamed the "Inca City" by NASA scientists due to its superficial resemblance to a ruined city. Like other formations in the area, the name 'Angustus' derives from a name given by

Eugene Antoniadi Eugène Michel Antoniadi (Greek: Ευγένιος Αντωνιάδης; 1 March 1870 – 10 February 1944) was a Greek-French astronomer. Biography Antoniadi was born in Istanbul (Constantinople) but spent most of his adult life in France ...

in 1930 to an

albedo feature An albedo feature is a large area on the surface of a planet (or other Solar System body) which shows a contrast in brightness or darkness (albedo) with adjacent areas. Historically, albedo features were the first (and usually only) features to b ...

that corresponds with the area. The name was approved in 2006.USGS
"Angustus Labyrinthus".
/ref> Angustus Labyrinthus was discovered by the ''

Mariner 9 Mariner 9 (Mariner Mars '71 / Mariner-I) was a robotic spacecraft that contributed greatly to the exploration of Mars and was part of the NASA Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from LC-36B at Cape Canaveral Air ...

'' probe, which photographed a small area that looked like the ruins of an ancient city. Mariner 9 team members named it the "Inca City". It looked like

sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

s that had formed from winds that blew from two different directions, but the dunes were too big. In 2002 the camera on Mars Global Surveyor revealed that the 'Inca City' was part of a large circular structure that was 86 km in diameter. So the shape meant that it was probably caused by an asteroid impact which cracked the crust. Later, magma flowed along the cracks. When the magma cooled, hard, erosion resistant walls of rock (dikes) formed. The crater was covered over, then partially exhumed. The hard walls of rock were left standing as softer surrounding material eroded away.Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.

References

Mare Australe quadrangle Valleys and canyons on Mars Albedo features on Mars {{Mars-stub