The Noctis Labyrinthus region (Latin for “labyrinth of night”) is located between the western edge of Valles Marineris and the Tharsis upland. It has a length of 1190 km and is characterized by a system of deep and steep-walled valleys formed by faulting. Many of the valleys show the classical appearance of so-called graben. A graben is a part of the crust that has subsided in relation to the blocks on either side. The faults typically dip toward the center of the graben from both sides. The fractures are witnesses of extensional tectonics. The intense volcanism in the Tharsis region was associated with an up-arching of large areas. This process resulted in tectonic stress, causing the crust to thin out and lead to the graben formation. Large plateaus representing the original surface level dominate the region. The intersecting canyons and valleys are up to 30 kilometers wide and up to six kilometers deep. There is no comparable landscape on Earth, nor on any other planet or moon in the Solar System. In many places, gigantic landslides can be found, covering the steep valley slopes and the valley floors. In other places, large linear structures can be found on the valley slopes. These structures are wind-blown sand deposits, accumulating to large dune fields. The alignment of the dune crests indicates that in some areas the sand was transported downslope, while in other places, the dune sand has been blown uphill.

Spectral investigations revealed layers of hydrated sulfates and clay minerals at the steep slopes. These minerals are indicative of aqueous environments in ancient times. It is very likely that Noctis Labyrinthus experienced an intense hydrological period when these rocks were formed. Elsewhere, long, extensively interconnected linear structures can be observed along the valley slopes. These are sand and dust deposits that have been shaped by wind into extensive ribbed fields whose ridges are separated by distances of 150 and 400 m. These sand ridges are oriented perpendicular to the wind direction and often formed on large bodies of sand or dune surfaces. The almost vertical orientation of the ridges on numerous slopes indicates that sand was transported parallel to the slope, while on the valley floors or on shallower slopes, the wind transported the fine-grained material from different directions along the valleys and also even uphill.

This mosaic consists of 8 HRSC images with a resolution of 12.5 m per pixel. In addition to the regular images, we also feature a downloadable GIS-ready digital terrain model (DTM) that can be used to further dive into this intriguing region of Mars. The anaglyph image is not as usual rendered with HRSC’s stereo channels, but instead by using the DTM information and the nadir mosaic to “virtually” generate an anaglyph. The annotated image shows the locations of interesting geological features. The mosaic is very large and contains many details that can only be seen by zooming deeply into the image.