When the mountain is both tall & too steep, it quickly crumbles. This sets something of an upper limit on how tall the mountain can be. Indeed, many of the wor

When the mountain is both tall & too steep, it quickly crumbles. This sets something of an upper limit on how tall the mountain can be. Indeed, many of the world's tallest mountains are more massive than they are steep. For extra credit, here's another competing theory: https://en.wikipedia.org/wiki/Glacial_buzzsaw https://en.wikipedia.org/wiki/Glacial_buzzsaw In short, glaciation & associated erosion grows significantly more aggressive with altitude, creating a sort of asymptotic limit to the height of a mountain.