Scientists have identified several hundred species of fossil plants and animals in Petrified Forest ... the area was designated a national monument in 1906 and a national park more than a half ...

Under a swath of Kentucky hills and hollows is a limestone labyrinth that became the heartland of a national park ... belly-crawling Wild Cave Tour, offered daily in summer and weekends year ...

Four types of volcanoes—shield, composite, cinder cone, and plug dome—can be found in Lassen Volcanic National Park, where they literally bubble and steam.