Chaotic terrain in Mars’ Pyrrhae Regio

This image from ESA’s Mars Express shows craters, valleys and chaotic terrain in Mars’ Pyrrhae Regio.

Chaotic terrain forms as a shifting subsurface layer of melting ice and sediment causes the surface above to collapse (a collapse that can happen quickly and catastrophically as water drains away rapidly through the soil). In the chaotic terrain seen here (to the right of the frame), ice has melted, the resulting water drained away, and a number of disparate broken ‘blocks’ have been left standing in now-empty cavities (which once hosted ice). Remarkably, these cavities lie some four kilometres below the flatter ground near the craters to the left – a colossal difference in height. For reference, the highest mountain peaks of the Pyrenees and the Alps top out at just over 3.4 km and 4.8 km, respectively.

This image comprises data gathered by ESA’s Mars Express using its High Resolution Stereo Camera (HRSC) on 3 August 2020 (orbit 20972). The ground resolution is approximately 16 m/pixel and the images are centred at about 322°E/16°S. This image was created using data from the nadir and colour channels of the HRSC. The nadir channel is aligned perpendicular to the surface of Mars, as if looking straight down at the surface. North is to the right.