Yellowstone Falls consist of two major waterfalls on the Yellowstone River, within Yellowstone National Park, Wyoming, United States. As the Yellowstone river flows north from Yellowstone Lake, it leaves the Hayden Valley and plunges first over Upper Yellowstone Falls and then a quarter mile (400 m) downstream over Lower Yellowstone Falls, at which point it then enters the Grand Canyon of the Yellowstone, which is up to 1,000 feet (304 m) deep.Upper Yellowstone FallsThe upper falls are 109 feet high. The brink of the upper falls marks the junction between a hard rhyolite lava flow and weaker glassy lava that has been more heavily eroded.Lower Yellowstone FallsCascading from the 590,000 year old Canyon Rhyolite lava flow, Lower Yellowstone Falls is the largest volume waterfall in the Rocky Mountains of the United States. These falls are 308ft high, or nearly twice as high as Niagara Falls. The volume of water flowing over Lower Yellowstone Falls can vary from 680ft3/s in the autumn, to 8400ft3/s at peak runoff in late springtime. The flow rate of Lower Yellowstone Falls is much less than that of Niagara Falls, as the Yellowstone River is only 70ft at the point at which it goes over the lower falls, whereas the Niagara River is 2600ft in width as it approaches the crest line of Horseshoe Falls.
