"This is not a geology book. Well, okay, this is a geology book. But I'm not a geologist: I'm a hillwalker who likes to know what's going on under my feet." (Granite & Grit: Introduction)

Over 30 years of walking, scrambling and climbing over Britain's geology – in the utterly confusing Lake District and the helpfully colour-coded hills of Torridon – I was waiting for the non-technical book with plenty of pictures to explain it all. In the end, I wrote it myself. And since then I've been studying, explaining, and photographing the rocks of the UK's mountains and seaside.

Geology is more than just learning the names and how many million years. It's looking at a rock and working out how the heck it got there, and what it tells about the very ancient history of this world we walk on, climb over and lie on top of on a beach towel.