Flagstaff Mountain rises in northeastern Washington southwest of Northport, with a summit of 4,255 feet and more than 3,000 feet of relief above the valley below. Its steep, rugged profile reflects a long geologic history. The mountain consists of Paleozoic sedimentary and intrusive igneous rocks that were later metamorphosed, faulted, and eroded into its present form. Near the summit, the Hubbard and Flagstaff Mountain Barite mines reflect the area’s mining past and its place within the mineral-rich geologic belt known as the Kootenay Arc.