[nitrogen]

> "This is a huge valley. There is no evidence of any geological formation on Earth that matches this scale," said Laurent Montesi.... The valley is about 250 miles wide and 600 miles long, with steep sides that dip as much as 2 miles below the surrounding terrain. To put this in perspective: if Mercury's "great valley" existed on Earth, it would be almost twice as deep as the Grand Canyon and reach from Washington, D.C. to New York City, and as far west as Detroit.

Although they were formed by a different process, this does sounds kind of like Earth's oceans. Do they not qualify as a geological formation?

[Swizec]

Near where I grew up there is a place called The Pannonian Plain. It's a remnant of a dried up sea.

So maybe we just don't call those geological formations valleys? https://en.m.wikipedia.org/wiki/Pannonian_Basin

[ubernostrum]

I believe Earth's oceans are generally thought of as the baseline, with the continents being relatively higher "plateaus" above them (rather than the continents being the baseline with ocean floors being "valleys" in between).

[tossaway1]

Either way, the Mariana Trench seems to dwarf the valley that's described in the article.