 The expedition recommenced its explorations in May 1860 . Raynolds led a party north and west up the upstream portion of the Bighorn River , which is today called the Wind River , hoping to cross the mountains at Togwotee Pass in the Absaroka Range , a mountain pass known to expedition guide Jim Bridger . Meanwhile , Maynadier led his party back north to the Bighorn River to explore it and its associated tributary streams more thoroughly . The plan was for the two parties to reunite on June 30 , 1860 at Three Forks , Montana , so they could make observations of a total solar eclipse forecast for July 18 , 1860 . Hampered by towering basaltic cliffs and deep snows , Raynolds attempted for over a week to reconnoiter to the top of Togwotee Pass , but was forced south due to the June 30 deadline for reaching Three Forks . Bridger then led the party south over another pass in the northern Wind River Range that Raynolds named Union Pass , to the west of which lay Jackson Hole and the Teton Range . From there the expedition went southwest , crossing the southern Teton Range at Teton Pass and entering Pierre 's Hole in present @-@ day Idaho . Though Raynolds and his party managed to get to Three Forks by the scheduled date , Maynadier 's party was several days late , which prevented a detachment heading north to observe the solar eclipse . The reunited expedition then headed home , traveling from Fort Benton , Montana , to Fort Union near the Montana @-@ North Dakota border via steamboat . It then journeyed overland to Omaha , Nebraska , where the expedition members were disbanded in October 1860 . 
