Dr. Ferdinand Vandeveer Hayden was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union Army during the Civil War.
In 1871, Hayden led a geological survey into the Yellowstone region of northwestern Wyoming. The survey consisted of some 50 men which included notables such as Thomas Moran, painter and famous frontier/Civil War photographer William Henry Jackson. The following year Hayden and his work Preliminary Report of the United States Geological Survey of Montana and Portions of Adjacent Territories; Being a Fifth Annual Report of Progress was instrumental in convincing Congress to establish Yellowstone as the first U.S. National Park, aided by Jackson's stunning large-format photographs and Moran's dramatic paintings. These publications also encouraged the westward expansion of the United States.
From his twelve years of labour and annual survey journeys there resulted a most valuable series of volumes in all branches of natural history and economic science; and he issued in 1877 his Geological and Geographical Atlas of Colorado. The last of the annual survey journeys was in 1878. As a result of Hayden's extensive geological work, he uncovered numerous dinosaur fossils which he brought back east with him for further scientific study. Much of what he brought back is still housed in the collection of the Smithsonian Institution. American paleontologist Joseph Leidy obtained most of his fossil specimens from Hayden.