Thomas Moran, Zion Valley, 1873, Gilcrease Museum, Tulsa, Oklahoma

Despite the enormous size of his most famous works, Moran may have been at his best in the small watercolor sketches he produced in the field. Nowhere perhaps is the romanticism of the age summarized more elegantly than in the small watercolor based on field studies Moran created in 1873 of the tiny boats carrying the Powell expedition down the Rio Virgin between the walls of Zion Canyon.