Career
He is principally known for his habit of leaving carved inscriptions in rock faces in Utah and Colorado on his travels, with at least eight such locations attributed to him, four of which are listed on the National Register of Historic Places. Julien apparently lived in Saint Louis in the 1790s. Denis witnessed the 1815 Iowa Treaty and traded on the upper Missouri River in 1816 and 1817.
In this time he was connected to the Chouteau and Robidoux families of Saint Louis.
In 1827 Julien made his first trip to the far West with Francisco Robidoux. They passed through Taos and went to "the land of the Utes," in the general area of Southern Utah and Colorado.
From that time Julien is known only by his series of rock inscriptions. He was the first to leave a dateable mark in the land in the area.
He left marks in 1831, 1836 and 1844, apparently traveling up and down the Colorado and Green rivers in a boat, apparently assisted by sail, since one of his inscriptions depicts a boat with a mast.
A Denis Julien inscription from 1836 was found in lower Cataract Canyon by Otis R. Marston in 1964. This inscription is now buried under the reservoir behind Glen Canyon Dam.