This is a nicely written book that investigates the Permian mass extinction event approximately 250 million years ago that wiped out 90% of all species on Planet Earth. The author starts with the history of geology and paleontology, and describes the various historical means of approaching geological problems. The author also takes a look at the Cretaceous mass extinction which killed the dinosaurs. This is an up-to-date (2015) edition of the book that includes new information on what caused the Permian mass extinction and how life recovered afterwards. There is a fair amount of technical terminology at the beginning of the book, but this doesn't detract from the beautiful writing and fascinating information.