That's a good point, George, although depth below the entrance is a
practical measure for cavers because that is how far they actually travel,
no matter how far below the surface they are.
I disagree with Mary, though. I think they do intend to portray how far
below ground the deep caves and
Actually, several of the caves (and probably some of the mines) are
misrepresented. The bottoms of very few deep caves are as far below the
surface directly above as their depth indicates, because caves don't go
straight down and the surface also goes up and down. Many deep caves have
entrances
