Fort Bridger Field Trip -- Hayden Yellowstone Expeditions

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 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.

The survey officially began on June 8, 1871 when it departed Ogden, Utah, although many survey members were already making observations and collecting specimens while the team was assembling in Salt Lake City and then Ogden. The party traveled north reaching Taylor's Bridge Idaho Falls) on June 25, 1871. On June 30, 1871 the survey party had reached into Montana, camping just over the Continental Divide near Monida Pass. Hayden and his survey party reached Virginia City, Montana on July 4, 1871 and Fort Ellis near Bozeman, Montana on July 10, 1871. By this time, Thomas Moran, the guest artist has joined the survey.

The expedition went into the Yellowstone area from Paradise Valley.

On the return -- the party went to Fort Ellis;  they camped on Medicine Lodge Creek in Idaho. They followed Medicine Lodge Creek down into the Snake River plain arriving at Fort Hall on September 18, 1871 camping where they had camped during their inbound journey on June 21, 1871.

By September 29, 1871 the survey party had reached Evanston, Wyoming Territory where they boarded a Union Pacific Railroad train to Fort Bridger, arriving there on October 2, 1871. At Fort Bridger, Hayden officially concluded the survey and disbanded the survey team. Hayden and Peale made their way to Salt Lake City and then back to Washington, D.C. Jackson and Charlie Turnbull at the urging of Hayden traveled to Nebraska where there photographed Pawnee Indians on the Omaha reservation.

(http://en.wikipedia.org/wiki/Hayden_Geological_Survey_of_1871#Survey_route)