By gully!

MARS RECONNAISSANCE ORBITER, 18 APRIL 2017

This gullied crater in Mars’s northern hemisphere was captured by the HiRISE instrument on the MRO in January 2017, but has only just been released by NASA. Gullies are steep slopes that are formed on Earth by flowing water, but on Mars their formation is thought to be driven by the build-up of frozen carbon dioxide over winter, which then sublimates into gas during Martian spring.