On this part of Mars there is an extensive surface brightness (albedo) boundary. One hypothesis is that this boundary marks a shoreline, from a time long ago when liquid water could have been stable on the surface of Mars.

With the resolution of HiRISE we can see that the reason one side of the boundary is darker than the other is due to the many boulders strewn across the darker side.

ID: ESP_071923_2260
date: 29 November 2021
altitude: 301 km

https://uahirise.org/hipod/ESP_071923_2260
NASA/JPL-Caltech/UArizona
#Mars #science #NASA