The expedition moved on and camped near the place we now call Fort Benton on June 4, 1805. For about ten days at this camp, the captains and their men worried over a big question: at the fork in the river, which branch was the real Missouri that would lead them to the Great Falls and the Rocky Mountains? Choosing the wrong fork could have cost them many weeks of hard travel in the wrong direction. On June 7, near the cliffs by the mouth of the Marias River, Lewis and one of the men, Richard Windsor, nearly fell from a steep bluff but managed to save themselves and climb back to safety. In the end, Lewis and Clark decided the clear, faster south fork was the true Missouri and followed it toward the Great Falls of the Missouri, while the other fork was named the Marias River and later proved to be only a tributary of the Missouri.