At night, he slept on a tiny platform. During the day, he climbed up the face of El Capitan, taking rock samples and detailed field notes along the way. (See "Climbing El Capitan.")

Putnam, a student of Allen Glazner, a professor of geology at the University of North Carolina, was gathering data for the first-ever high-resolution geologic map of El Capitan, one of America's most iconic natural landmarks and a jewel in the crown of Yosemite National Park in central California. The work was supported by the National Geographic Society.