Yup, Treehands is dead right, sand has killed more dogs than rock ever did!
As for rock dogs, my first good terrier was born out of rock dogs. Big Kev Stone from Wigan bred him, out of a Tyson dog Jack, to a Cowan bitch Lassie.
Jack was your text book digging dog, a good finder, staying till dug, in big places, a black n tan that was both a looker and a real worker. He looked and worked every inch the line he was from, big boned, hard coated and dead steady. A bayer that loved to get a grip when you broke through.
Lassie was a bit different, though still black n tan, she was light boned,