You are standing on the inside of a mountain. Not on top of one. Inside. The rock under these hills spent its early life twenty kilometers underground, inside a mountain range that is not there anymore.
To bury a rock that deep, you have to stack something enormous on top of it. Two continents did the stacking. Gondwana came up from the south. Laurussia held the north. Between them was an ocean, and the ocean was closing.
Push two carpets together on a floor and one slides under the other. That is what a sea floor does when a continent arrives. It bends, it goes under, and it carries seawater down with it. Water makes hot rock melt more easily. The melt rises, and the crust above it grows thicker.
Beds of rock that had lain flat for a hundred million years started to fold, the way a sheet of paper folds when you push both ends together. Where the folds reached daylight, the ground went up. The new range was so heavy it pressed the ground beside it down into a long trough. Rivers filled it with sand, grit and iron-stained mud. Every grain of it used to be mountain.
So how high did those mountains stand? Here is the honest answer: nobody can measure it. The summit is gone, and there is nothing left to hold a ruler against. Every height you have heard for this range is somebody's best guess, worked backward.
But the rock that is left can tell you how deep it was. Squeeze rock and heat it, and its minerals rearrange in a fixed order. About ten kilometers down, mud turns into a rock called schist, its flat minerals all swung into line, like dry spaghetti squeezed between your palms. Twenty kilometers down, rock stops splitting and starts to flow like warm putty. Forty kilometers down, nothing of its old texture is left at all.
The rock in the oldest core of this range reads twenty kilometers and deeper. That part is measured, not guessed. Nobody knows how tall these mountains stood. But their crust was thickened the way the biggest mountains on Earth are thickened.
Then the range came apart, and nothing about it was dramatic. Rain. Frost. Rivers. A mountain is not knocked down. It is carried off one grain at a time. In the Smoky Mountains today, that comes to about twenty-five meters of rock every million years. Eight floors of a building, every million years.
And underneath, something quieter was happening. A mountain range hangs a keel of thick crust down into hotter rock, and the whole block floats, like wood in water. Take the top off and the block rides up. Take enough off, over enough time, and the deepest part of the range arrives at the surface last.
Here is what is left. The highest point in the whole chain is Mount Mitchell, just over two thousand meters, with a road and a parking lot at the top. So look at these hills again. You are not looking at a small mountain range. You are looking at the bottom of an enormous one.