A waterfall lacking the important attribute of water is called a dry fall. Georgia O’Keeffe responded to one with the painting Cliffs Beyond Abiquia, Dry Waterfall, and a dry fall in Grand Canyon’s Obi Canyon is often cited as a prime example. The most dramatic dry fall in the world, three and a half miles wide with a drop of over four hundred feet, is in Sun Lakes State Park, Washington. The skeleton of the greatest waterfall known to have existed on Earth, it is a feature of Grand Coulee Canyon, part of the Channeled Scablands that cover nearly half of eastern Washington. Though unenthusiastically described by some viewers as a wide, bare canyon-walled hole, Dry Falls has an impressive geological pedigree. Fourteen to sixteen thousand years ago, when vast lakes in present-day Montana repeatedly broke through glacial dams, the Missoula Floods raced across the Northwest. Tremendous waters pushed along the ancient course of the Columbia River, gouging rock and sculpting precipices. This ancient giant cataract was so powerful it couldn’t sustain itself. Retreating, it vanished.