From October 9 to 12, 1939, a Sierra Club climbing team including Brower, along with Bestor Robinson, Raffi Bedayn, and John Dyer, completed the first ascent of Shiprock, the erosional remnant of the throat of a volcano with nearly vertical walls on the Navajo reservation in northwestern New Mexico. This climb, rated YDS III, 5.7 A2, was the first in the United States to use expansion bolts for protection.