Once most of the major mountains were climbed, thrill seekers turned to another form of conquering peaks: falling from them. Jumpers would scale any fixed surface high in the air, from skyscraper roofs to bridges to cliffs, and jump off, opening their parachute in mid-flight. The practice came to be known as B.A.S.E jumping, the acronym standing for Buildings, Aerials, Spans (bridges), and Earth (cliffs), and was pioneered by Mike Pelkey, Brian Schubert and Jim Cleary, the first ones to parachute off from the “earth” — a 3,000-foot cliff in the Yosemite valley known as “El Capitan.”

On this day, July 24, in 1966, with no experience in jumping from cliffs, and missing much of the gear standard for base jumpers today, Pelkey and Schubert, both 26, hiked up the trail to the top of El Capitan, threw off their hiker disguises, and jumped off the top.

Both men deployed their parachutes without a hitch, but the gusty winds in the valley proved tough to ride out in their modified military parachutes. Schubert slammed into the cliff about 50 feet from the ground and rode down the first of the way feet-first, while Pelkey fractured his ankle in a collision with the cliff after he tried to maneuver himself into the wind. Both men spent some time in the hospital, but both came away happy having made the first ever base jump from a cliff.