Joel Duff

From the Introduction: "The Grand Canyon of the Colorado River is one of our plant's most compelling and recognizable landforms. ... It is the rare individual who, upon seeing the Grand Canyon for the first time, does not ask, 'How could this have formed?' ... It took centuries, even millennia, for humans to comprehend that the history of our planet is contained in rocks, but once this insight was achieved, the story of planet Earth began to be understood....