Hayden Geological Survey of 1871

The Hayden Geological Survey of 1871 explored the region of northwestern Wyoming that later became Yellowstone National Park in 1872. It was led by geologist Ferdinand Vandeveer Hayden. The 1871 geological survey was not Hayden's first, but it was the first federally funded geological survey to explore and further document features in the region soon to become Yellowstone National Park, and played a prominent role in convincing the U.S. Congress to pass the legislation creating the park. In 1894, Nathaniel P. Langford, the first park superintendent and a member of the Washburn-Langford-Doane Expedition which explored the park in 1870, wrote this about the Hayden expedition:We trace the creation of the park from the Folsom-Cook expedition of 1869 to the Washburn expedition of 1870, and thence to the Hayden expedition of 1871, Not to one of these expeditions more than to another do we owe the legislation which set apart this "pleasuring-ground for the benefit and enjoyment of the people"