The Heyburn Divide runs east from the main Sawtooth crest at Braxon Peak and encompasses some of the most challenging Sawtooth formations. This divide, its routes, and history are discussed in the book on Pages 171 to 176. The divide was the first to catch the interest of mountaineers following in the footsteps of the Underhills. The West Pinnacle and Mount Heyburn’s two summits crown the eastern end of the ridge. Between Braxon Peak and the West Pinnacle are five extraordinary granite formations that were first described by Robert Underhill: the Grand Aiguille, Small Aiguille, Black Aiguille, Split Tooth, Splinter Towers, and Peak 10014. The divides peaks and formations on the website are at this link: Heyburn Divide