In The Mysteries of Terra Firma, Powell — the author of Night Comes to the Cretaceous and Grand Canyon: Solving Earth's Grandest Puzzle, as well as the former president and director of the Los Angeles County Museum of Natural History — describes the development of our understanding of the history of the earth by focusing on three themes: Time, Drift, and Chance. For a lucid explanation of the dating techniques used to establish the age of the earth, the revolution wrought by Wegener's theory of continental drift, and the role played by chance asteroid impacts in the history of the earth, look no further. "An accessible, lively account of the biggest questions in earth history," writes the reviewer for Booklist.