The vast canyon system on Mars, revealed in Strange New Worlds to be a scar left by an ancient war with the Dol'drm.
Valles Marineris is the enormous canyon system on the surface of Mars and gives its name to the fourth season premiere of Strange New Worlds. In the episode, the time-displaced Enterprise discovers that ancient Martians were at war with the Dol'drm 65 million years ago.
The canyon turns out to be a scar left on Mars when a Dol'drm ship was shot down and crashed there during that war. The conflict ends with the destruction of the Dol'drm homeworld, which also begins Mars's decline into a barren world.