The Corps of Discovery passed this unique outcropping on May 31, 1805, which William Clark remarked in his journal, “high Steep black rock riseing from the waters edge.” He described it, but didn’t name it.
It would not be until the steamboat era nearly 50 years later when this fortress-like feature would be named Citadel Rock. Geologists will appreciate this igneous intrusion, originally covered with sandstone that washed away, leaving the harder basalt pillar to mark the curve in the river’s path.
It was near here that the men almost lost the white pirogue – when a tow rope snapped and the boat struck a large rock, nearly tipping over into the current. That rope was the final one made of hemp.
Learn more: http://www.lewis-clark.org/article/2910
Source: The Journals of Lewis and Clark and Lewis-Clark. org