Northern Prairie Wildlife Research Center
In 1856, Hayden was appointed to be the chief naturalist on the Warren expedition. This was a military expedition with orders to explore the Yellowstone River. However, the expedition first made a brief trip up the Missouri by boat about 60 miles above Fort Union and then returned to Fort Union where they were able to purchase some of Sir George Gore's wagons and supplies. They then slowly traveled up the Yellowstone to the mouth of the Powder River (Figure 15). In addition to fossils, Hayden collected plants, mammals, birds, fishes, reptiles, and amphibians. Although the Warren Expedition did not achieve its military objective, it produced a wealth of natural history information. Warren also led expeditions into the Dakota and Nebraska territories in 1855 and 1857. In this latter year, he was within sight of the Black Hills but was turned back by Souix Indians.
Schubert, F.N., ed. 1981. Explorer on the northern plains: Lieutenant Governor K. Warren's preliminary report of explorations in Nebraska and Dakota in the years 1855-'56-'57. Engineer Historical Studies, No. 2. Office of the Chief of Engineers, Washington DC. Warren, G.K. 1858. Preliminary report of explorations in Nebraska and Dakota in the years 1855-'56-'57. U.S. Govt. Print. Off., Washington DC.