Actually from the window in the TurtleBack Rock pic I posted in another topic, you can look through and see the mouth of a branch, up this branch is a area where you can find a very small hole in the ground. It actually drops down about 10ft like Swift describes and levels off. It's a dangerous cave with the creek running underground and huge sink holes and drop offs. I've been in this cave once, but that was before I got into the Swift legend.. Area fits the description of the middle mine location.