Petrified Forest National Park

History: How the Petrified Forest Was Formed

©2006 National Park Service These and other great trunks line the landscape of the Petrified Forest.

The history of the Petrified Forest area goes back more than 225 million years. Scientists believe that, eons ago, great herds of dinosaurs roamed through forests of tall conifers, while nearby rivers teemed with armor-scaled fish. The great columns of petrified wood scattered across the desert date from around that time.

Nature produced the mineralized wood under very special circumstances. The trees were uprooted by great floods or perhaps flows of lava, then washed down from the highlands and buried by silt and volcanic ash. Water seeping through the wood replaced decaying organic material cell by cell with multicolored silica.


Eventually, the land where the great logs were buried was lifted up by geological upheaval, and wind and rain began to wear away the overlying sediments, finally exposing the long-buried, now petrified wood.

Each piece of wood is unique, burning with the colors of the Painted Desert, of which Petrified Forest National Park is a part. Some of the great trunks still bear the annual rings that reveal their life histories in prehistoric times.

Petrified Forest History: Inhabitants and Exploration

The Paiute believed that the petrified logs were the great arrow shafts of their thunder god, Shinauv. The Navajo said they were the bones of a mythological giant, called Yietso.

After American explorers found these great "stone trees" in the mid-nineteenth century, a steady stream of visitors began making the trek to Petrified Forest. A military survey party passed through the region in 1851, and its members filled their saddlebags with pieces of the petrified wood.

By about 1870, great quantities of glistening rock were being carried off by souvenir hunters and commercial developers, who cut slabs from the logs for tabletops and mantles. Petrified wood was also blasted apart in search of valuable amethysts or quartz crystals that some of the wood contains.

A mill was built to grind the great logs into abrasives. Concerned citizens went to the Arizona Territorial Legislature to seek federal protection for the area, and Petrified Forest was declared a national monument in 1906.

So take a road trip and check out what the U.S. government so rightly wanted to protect. It's not every day you can witness natural beauty that's more than 200 million years old.

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