The beauty of that dance can be difficult to capture, however. More than 35 trillion tons of water are released into the world's oceans each year through river channels. Nowhere is the immense power of that weight felt more strongly than at waterfalls. Stand at the lip of the Lower Falls in Yellowstone at high water and the rocks tremble beneath your feet. It is a power that can sculpt landscapes.
Geologists say that water flowing just one foot per second can move gravel.
This is the power that has created many of our backcountry waterfalls. Some falls, particularly in the high country, are the result of valleys that were left hanging high above a canyon floor when a glacier barged through. As water moves across land, softer rock layers erode more quickly than hard layers. If the soft layers lie downstream of more resistant rock, an inclined riverbed is formed, increasing the speed of the flow, which in turn increases the cutting power of the water. That increases the incline, which in turn again increases the cutting force in the water.