The Yellowstone River roars over Lower Falls on its way through the Grand Canyon of the Yellowstone. Every second 37,417 gallons of water plunges over the falls. The Lower Falls at 308 feet is the second, and taller, of a pair of falls along the Yellowstone River. One quarter mile upstream is the Upper Falls which is 109 feet in height. The Grand Canyon of the Yellowstone stretches for approximately 20 miles from Upper Falls to Tower Junction. The depth of the canyon ranges from 800 to 1200 feet.