The United States Congress designated the Petrified Forest National Wilderness Area (map
) in 1970 and it now has a total of 50,260 acres
All of this wilderness is located in Arizona
and is managed by the National Park Service.
About 225 million years ago this area was a vast floodplain crossed by many streams. Tall, stately, pinelike trees grew here, sheltering a myriad of reptiles. When the trees fell, they washed into the water to be buried under silt, mud, and volcanic ash. Groundwater seeped through the logs, bearing silica that later crystallized into quartz, which ultimately petrified the wood. After centuries of burial and upheaval, the land became the high, dry Arizona tableland seen today. While the forces of erosion sculpted the Painted Desert, they also brought the petrified wood slowly to the surface. In 1906, the United States established Petrified Forest National Monument. By 1962, the area had been expanded and its name was changed to Petrified Forest National Park. Over half of the park has been designated Wilderness.
Interstate 40 cuts through the park. North of the highway lies the protected portion of the Painted Desert, most of it preserved as Wilderness. A large piece of the southern portion of the park, primarily along Puerco Ridge, has also been designated. In addition to the petrified wood logs, visitors can observe remnants of petro-glyphs and stone houses built by early human settlers to this region, dating back approximately 2,000 years. Wilderness backpack camping is allowed in the National Park.