On July 3, 1806, Capt. Clark and 12 members of the Corps left Traveler's Rest to explore the Yellowstone River, intending to canoe its entire length, but Clark found no timber sufficiently large for his purpose. On July 18, near present-day Columbus, Sgt. Gibson was seriously injured, forcing Clark to stop the next day south of Park City and construct two small dugout canoes, and the party proceeded on July 24. The actual location of Canoe Camp had interested Lewis and Clark historians and local enthusiasts since 1893, and beginning in 2010 an intensive study using additional information and modern mapping equipment and technology made it possible to position Clark's camp symbol more accurately and identify a promising location for archaeological investigation. An archaeology study begun by MSU Billings in 2011, with funding from the Lewis and Clark Trail Heritage Foundation, National Park Service, MSU Billings, and the Rochejhone and Headwaters Chapters, with assistance from MSU Billings students, the Boy Scouts of America, and others, led to a confident identification of the site. Recovered artifacts including mercury and lead matched the expected military camp layout of the fire pit, latrine, and distance from the river; mercury, used as a medicinal salve and in Dr. Rush's pills called thunderclappers, was considered positive evidence because it was used only by the Corps, and the lead composition matched material found at Traveler's Rest and from Kentucky mines known to have supplied lead for the expedition.