The island was first recorded in the journal of Fr. Jacques Marquette, S.J., in 1673. The locals warned him of the dangers of navigating past the island, whose swift waters could easily cause shipwreck. More information is here.
Father Jean-François Buisson de Saint-Cosme, S.J. visited Tower Rock. According to a history written by James M. Gallen:
On the feast of the Immaculate Conception, December 8, 1698, St. Cosme said the first mass at what would become the mission of Sainte-Famille. After celebrating mass, St. Cosme and his party left the Tamarois on the afternoon of the eighth. Traveling down river, he mentions landmarks believed to be in Perry County, Missouri. He relates the passage of a rock about one hundred feet high which was said to create dangerous whirlpools during high water. This feature is now known as Tower Rock, and, on occasion, by other names, including Rock of St. Cosme. In keeping with the natives’ custom of offering sacrifice after a successful passage of the rock, St. Cosme and his party ascended the rock and planted "a fine cross on it, chanting the hymn Vexilla Regis, while our people fired three discharges from their guns."