THEMIS Image of the Day, May 1, 2019. Angustus Labyrinthus is a unique region near the south polar cap. The squares formed by intersecting ridges earned the feature the informal name of the Inca City when it was discovered in Mariner 9 images in 1972.
The linear ridges are believed to have formed by volcanic and tectonic forces, where magma filled fractures in the subsurface and then erosion revealed the magmatic material.
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