Appalachian Trough
Some routings of the Trail have been in the same location for so long, seen so much foot traffic, or eroded such that it's a twelve inch wide trail by eight inches DEEP. This section, just before the final climb up this hump that hides the Dome, is a good example.
The hump in the distanct is blurry from my horrid camera (or the lackluster skillset of the photographer), but illustrates the spruce fir biome dominating the highest peaks of the Smokies.