Growth: Development | Progress | Extension
Ok, not really on prompt, however this is what I'm going with. This is the Lower Yellowstone waterfall where it enters the Grand Canyon of the Yellowstone. Guess this canyon has taken a long time to form.
Some information from good old Wikipedia:
The lower falls are 94 m high, or almost twice as high as Niagara. The volume of water is in no way comparable to Niagara as the width of the Yellowstone River before it goes over the lower falls is 22 m, whereas Niagara is 800 m. The lower falls descend from the 590,000 year old Canyon Rhyolite lava flow. The lower falls of the Yellowstone is still the largest volume major waterfall in the Rocky Mountains of the United States. The volume of water flowing over the falls can vary from 240m³/s at peak runoff to 19 m³/s in autumn.