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 .
Hemmed-In-Hollow Falls
Hemmed-In-Hollow Falls is a single-drop waterfall located within the Ponca Wilderness Area of the Buffalo National River in northern Arkansas. The height of the falls is 209 feet (64 meters). According to the National Park Service, it is the "Tallest waterfall between the Rockies and the Appalachians."