A river you could wade across in September carved a canyon deep enough to hide a skyscraper. That contradiction is where this book starts, and it takes about 180 million years to explain. Written for readers ages 9 to 12, this is the full history of a canyon in southern Utah — the sand sea that became its walls, the dinosaur tracks pressed into mud beneath them, and the people who have been standing at the bottom looking up for at least ten thousand years. Families farmed the canyon floor and built stone pantries into the cliffs. The Southern Paiute knew every spring and every route to the rim, and their descendants live an hour up the road today. Then came settlers, surveyors, a painter who made the place famous, and a president who signed a name onto it that nobody had checked with the people whose language it came from. A teenager spent twenty-five years building a two-thousand-foot cable to bring lumber down a cliff. Crews with dynamite dug a mile-long tunnel through solid sandstone by rappelling in from the side. Nineteen-year-olds in the Depression built trails that millions of people walk without knowing who laid the stone. Thirty chapters cover geology, archaeology, engineering, disaster, and the argument now underway about what happens to a park that five million people want to visit at once. Where historians disagree — whether a climber really reached a summit in 1927, what the canyon was called before 1909 — the book says so instead of picking the better story. Includes a timeline, a glossary, brief biographies, and a guide to what's still standing.