On its journey to the Pacific Ocean, the Lewis and Clark Expedition camped near here on September 2, 1804. At this camp, the explorers’ imagination and knowledge of military fortifications misled them into concluding that sand ridges and mounds left by Missouri River floods were an ancient fortification. Captain Clark made a detailed survey of these natural features. Clark also recorded his concern for Private George Shannon, the youngest member of the Corps of Discovery at 19, who had been missing for five days after going in search of stray horses and was not found until September 11. Clark wrote that Shannon had been 12 days without anything to eat but grapes and one rabbit, which he killed by shooting a piece of hard stick in place of a ball, and that, supposing the boat to be ahead, he pushed on as long as he could until he became weak and feeble and decided to stop and wait for a trading boat.