Yellowstone National Park
Yellowstone National Park has one of the world's largest petrified forests, trees which were long ago buried by ash and soil and transformed from wood to mineral materials. This ash and other volcanic debris are believed to have come from the park area itself as the central part of Yellowstone is the massive caldera of a supervolcano. The park contains 290 waterfalls of at least , the highest being the Lower Falls of the Yellowstone River at .
Horsetail Fall (Yosemite)
This waterfall descends in two streams side by side, the eastern one being the larger but both quite small. The eastern one drops , and the western one , the highest fully airborne waterfall in Yosemite that runs at some point every year. The waters then gather and descend another on steep slabs, so the total height of these waterfalls is to . The image shown here is taken during a brief time during the winter, near February 21 at sunset, made famous by Galen Rowell's photograph.