The Petrified Forest: A Library in Stone

Located in northeastern Arizona, visitors to the Petrified Forest National Park can drive a 28-mile one way trip back in time to an ancient landscape where the dinosaurs roamed.

Two hundred million years ago during the Late Triassic, the North American continent was several thousand miles southeast of its present location. Ancient Arizona was located near the equator with a warm tropical climate. Rains flowing down the surrounding mountains into streams and rivers traversed a low-lying plain. Floods deposited sediments across the plains creating swamps and small lakes teeming with prehistoric life.


A painted scene inside the Rainbow Museum and Visitors Center. Scientists piece together fossil remains to provide information to recreate the ancient landscape.

The Petrified Forest National Park is one of the world's largest concentrations of petrified wood and fossil remains of plants and animals. Ancient floods during the Triassic period trapped plant and animal matter beneath sediment compressing the cells and slowing decay. As water percolated through the mineral-rich sediments, minute silica crystals formed within the spaces of cell structures forming permineralized fossils. In the hollow cavities of buried logs, large crystals of amethyst and rock quartz formed. The rainbow of colors observed in the petrified logs indicate the elemental substances contained in the terrain from millions of years ago.

Minerals are represented by the color: Red, Orange, Yellow or Pink is iron, White is quartz, Blue is copper, Grey or Black is carbon manganese, Green is copper or chromium.


Quartz crystals in a petrified log in the Crystal Forest.

Nearly 200 species of plant fossils have been identified and less than a dozen are petrified wood. The largest group is spores and pollen grains. The rest of the fossils contain compressed leaves, stems, and seeds of mostly conifers, cycads, and ferns. All the fossilized plant species are now extinct.

Living among a stone library, Cholla Cactus or Cylindropuntia, is a native of the contemporary arid landscape that began about 60 million years ago. Over 400 species of plants, mostly grasses, are identified in the area today.

Visitors to the Petrified Forest traverse time and space to an alien landscape where the native people of the Southwest believed the petrified logs were the broken arrow shafts of their gods or the bones of slain monsters of legends. A trip to the park's fossil collection at the Rainbow Museum will convince that giant beings indeed once roamed the Earth.

My mother and I cast our shadows onto a petrified landscape.

The Petrified Forest is easily accessible from Highway 40 in Northeastern Arizona. Tourists can drive through both the Painted Desert and the Petrified Forest or spend the night in another world with a back country permit. Open daily with hours of operation depending on the season. Pets are welcome. Removal of the petrified wood is prohibited. For more information visit The National Park Service website or click here.

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