The ninth book in the bestselling series tells the story of John Wesley Powell, the one-armed geologist who explored the Grand Canyon

John Wesley Powell (1834–1902) always had the spirit of adventure in him. As a young man, he traveled all over the United States exploring. When the Civil War began, Powell went to fight for the Union, and even after he lost most of his right arm, he continued to fight until the war was over. In 1869