Brains
This video is a very educational 1 minute and 45 seconds of plate tectonics, gravity, rock density, erosion, history, geology, and Mars geography.
To be honest, I’ve never heard any kind of discussion like this before.  How tall can a mountain get on Earth?  I figured they could get pretty tall.  Especially considering Olympus Mons on Mars is 90,000 feet tall.  You’d think that on Earth, we could grow a mountain at least 40,000 feet tall.  Apparently not.  Looks like Earth has done a fantastic job a mountain growing.  Great video.
cute