Lushington D. Brady: Scientists Drill Deep into the Earth’s Mantle

In C S Lewis’ The Silver Chair, a gnome from the land of Bism, at the bottom of the world, scoffs at surface-dwellers’ mines. “I have heard of those little scratches in the crust that you Topdwellers call mines.”

“Scratches in the crust” is putting it mildly. The deepest mine on Earth, the Mponeng gold mine, is four kilometres deep.