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 .
Yellowstone Falls
The upper falls () are 109 feet (33 m) 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.