Dr Nick Mortimer has been a New Zealand based professional geologist for more than 25 years. His areas of expertise include mineralogy, structural geology and tectonics. Hamish Campbell has been a professional geologist in New Zealand for more than 30 years and is best known for his role as geologist and science commentator at Te Papa. Margaret Low is happiest behind a camera and works as a science photo-librarian and photographer. All three authors are employed by GNS Science.