Ribbon Fall, cataract on the west slope of the Sierra Nevada in Yosemite National Park, east-central California, U.S. With a drop of 1,612 feet (491 metres), it is one of the world’s highest waterfalls—said to be the highest single fall in the United States—and one of the park’s most scenic features. Reaching a peak volume during May and June, it is fed mainly by melting snow; hence, it is sometimes dry for brief periods in midsummer. See also Bridalveil Fall.