The primordial past comes to life at Petrified Forest National Park, in remote northern Arizona. Created in 1906 by President Theodore Roosevelt, this park preserves the Chinle escarpment, a globally significant fossil repository stretching for 22 miles. The huge formation—once a verdant woodland—contains plant and animal remains dating back 220 million years, from crocodile-like phytosaurs to armored, plant-eating aetosaurs. Even if you’ve visited the park in the past, it has been gradually growing thanks to support from the Conservation Fund and other organizations—more than 45,000 acres have been added to the park since 2007. Archeologists are discovering petroglyphs, paleontologists are surveying new lands, and recent discoveries await every visitor.