Wow – what a shot by Mars Express! Mars has several regions of what is called ‘chaotic terrain’. These are areas with large accumulations of rocks of varying sizes, as well as flat-topped features. These erratically shaped rocks are large, too: between 1-10 km in size. Some chaotic terrain on Mars is thought to form when there is a sudden removal of subsurface water or ice, causing the surface material to slump and break into blocks. The region shown here, however — Ariadnes Colles — is not a water-source region, so scientists are still debating whether Ariadnes Colles was formed by the action of water or wind. Either way, this is a very interesting region. See below for a straight on view that’s just as incredible.
A large impact crater, 1200 m deep, is visible on the right, which has a smaller crater inside of it. The larger crater is about 30 km in diameter and covers an area roughly the size of Hamburg, Germany. The smaller younger crater lies almost at the center of the older one, and has a diameter of just 10 km.
Interestingly, the blocks, or mesas have a striking lineation, as almost all are oriented in the northwest-southeast direction. By looking at the larger versions, it’s possible to see the northwestern flanks have been eroded more strongly than the opposing southeastern ones.
Some slopes of the flat-topped mesas have been covered by darker material, likely sand or volcanic ash that was blown up on the slopes.
Anyone ready to visit this interesting region?