Desire: In my world, I would like to have a (potentially unreasonably) large mountain range that is so large both in height and width that it is both entirely impassable, and disappears into the clouds with unseen peaks, even when viewed from miles off.
Confession: My knowledge of the science on this is shaky at best. I found another answer on this site that asked for hard science, and yielded that on earth the tallest possible is around 10 km, but I would like to make it much larger, preferably without handwaving.
Goal for Answer: I have no problems with coming up with fantastical ideas for how it became that tall (Massive flooding event that crashed tectonic plates together, remains of an unimaginably large asteroid, etc.), but I am weak in an actual scientific basis. I don't need "hard science" per se, but would like an at least semi-plausable way to explain how it's possible without simply being logistically inane. I'm concerned this size might warp the rotation of the planet, or cause other issues I'm not thinking of, as I'm simply a lowly politics major ;)