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 .
Multnomah Falls
Multnomah Falls is the tallest waterfall in the state of Oregon. It is credited by a sign at the site of the falls, and by the United States Forest Service, as the second tallest year-round waterfall in the United States. However, there has been some skepticism surrounding this distinction, as Multnomah Falls is listed as the 156th tallest waterfall in the United States by the World Waterfall Database (this site does not distinguish between seasonal and year-round waterfalls). The World Waterfall Database disputes claims that Multnomah Falls is the fourth-tallest waterfall in the United States, which has been claimed in such sources as the "Encyclopedia of World Geography" (2014).