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 .
Yosemite Valley
Yosemite Valley ( ) is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about 7.5 miles (12 km) long and approximately 3000–3500 feet deep, surrounded by high granite summits such as Half Dome and El Capitan, and densely forested with pines. The valley is drained by the Merced River, and a multitude of streams and waterfalls flow into it, including Tenaya, Illilouette, Yosemite and Bridalveil Creeks. Yosemite Falls is the highest waterfall in North America, and is a big attraction especially in the spring when the water flow is at its peak. The valley is renowned for its natural environment, and is regarded as the centerpiece of Yosemite National Park, attracting visitors from around the world.