The Green River in Labyrinth Canyon showing the saddle of the Bowknot, photographed by John K. Hillers during Powell's 2nd expedition in 1872. The saddle of the Bowknot. Major John Wesley Powell was a soldier who lost his arm in the Civil War, and went on to become a geology professor, American Indian expert, western conservation advocate, and an explorer who's most famous expedition was a 900-mile journey on the Green and Colorado Rivers in 1870.