It isn't apparent with this photo, but if you look down at the point where the roots come off the main trunk, the roots form a ring. I can't be sure, but it appeared to me that this tree grew as a seedling in an old tree stump, sending its roots down through the rotted wood. In time, the stump rotted away, leaving the roots as you see them. There was no trace of the stump left. This photo was taken during a backpacking trip in the Red River Gorge Geological Area in Kentucky.
