Petrified Forest National Monument

The most spectacular manifestations of petrified wood known in the world, as well as the most colorful portions of the Painted Desert, are included in the Petrified Forest National Monument, east of Holbrook in Northern Arizona. Unique in its vivid and varied colors, the petrified wood of this area has long attracted the interest of visitors from all parts of the world. Six separate "forests" within the boundaries of the Monument, and many regions containing fossil remains of animal life and other plant life besides the petrified wood, are all of great popular and scientific interest. There are more than a hundred pre-Columbian Indian ruins within the Monument in addition to thousands of Indian petroglyphs on the weathered sandstone cliffs.

Attention was first directed to the petrified forests of Northern Arizona in the 1850's, but it was not until 1906, in response to the petition of citizens of Arizona, that the area was made a national monument to protect the petrified wood from exploitation and vandalism. Covering an area of 141 square miles, the Monument is administered by the National Park Service, United States Department of the Interior.

About 160 million years ago Northern Arizona is believed to have been a lowland where shifting streams spread sand and mud over the plains. Trees, ancestral to the modern Araucarias of South America and Australia, grew in favorable spots, together with cycads, rushes and numerous kinds of ferns. Crocodile-like reptiles and giant salamander-like amphibians inhabited lowlands, rivers and marshes.

It was no sudden catastrophe, but rather the slow, natural processes, occasionally hastened by destructive fires and the ravages of insects, that are believed to have killed the trees even as these enemies kill forest trees today. Many of the trees, certainly, decayed on the ground, but others fell into streams and rivers and came to rest in bays or on sand bars where rapid burial by mud and sand prevented their decay. The deposits in which these trees were buried were eventually turned to hard sandstones and shales, and are now called the Chinle formation. The Chinle deposits were themselves buried at least 3,000 feet beneath layers of sand and silt spread by shallow seas.

While buried, the logs were saturated with water in which a mineral called silica was dissolved. Through some process the wood was removed, perhaps by solution, perhaps by a kind of decay, and as each wood cell disappeared, an equal amount of silica formed in its place. This substitution of mineral for wood was eventually so complete that not only was the form and shape of each log duplicated, but even the grain and microscopic cell structure in some specimens were perfectly reproduced. The silica was variously and beautifully colored by oxides of iron and manganese. The banded variety is called agate or onyx, the red opaque form is jasper, the translucent red is carnelian, and so on through a long series of colors and textures.

Long after the logs were buried the mountain highlands of Western America began to take shape and the Northern Arizona plateau was lifted several thousand feet above sea level. Immediately wind and water began to erode the thick burden of sandstone and shale from above the petrified forests. For nearly 60 million years this erosion has slowly progressed until during our own time certain parts of the forests are again being exposed on the surface of the earth. Many logs lie exactly where erosion has uncovered them, but in other places deeper erosion has caused some logs to sink to lower levels where broken fragments and sections accumulate in irregular piles. Doubtless much fossil wood has been completely removed by erosion, but just as cer-tainly much more remains still buried in the rocks.

Some of the shales formed during the Triassic period were exceptionally highly colored in red, yellow, blue and white.

The beautifully "painted" and carved badlands formed where these colored shales have been eroded into steep ravines, rounded knolls, turreted ridges and flat mesas, no doubt suggested to the early Spanish explorers the singularly appropriate name "El Pintado Desierto" or Painted Desert.

The ruins of pueblos built by Indians in pre-Columbian times, from 800 to 1,400 years ago, are scattered on nearly every mesa throughout the Monument. Low mounds, strewn with blocks of sandstone and bits of broken pottery, mark the fallen walls of these ancient homes. Sometimes these dwellings, such as the Agate House in the Third Forest, were built of blocks of petrified wood, and smaller fragments of this material were chipped into arrowheads, knives and scrapers. These Indians were undoubtedly related to the other pueblo builders and cliff dwellers of the times, and the modern Hopi and other Pueblo Indians are thought to be their descendants. Petroglyphs, graven on nearby sandstone cliffs, might tell something more of these ancient inhabitants if these picture writings could be interpreted.

The Puerco River Indian Ruins, located near the Ranger Station is the largest pueblo ruin accessible in the Monument. Three of its more than 100 rooms have been excavated. The Newspaper Rock, a cliff covered with petroglyphs has been called "the classic example of petroglyphs in the Southwest." Pictures of this sort have never been interpreted, but easily recognizable are representations of men and women, phallic symbols, antelope, lizards, snakes, birds, and geometric designs. The most brilliant section of the Painted Desert contains the Black Forest, a newly acquired section of the Monument and as yet, inaccessible. In this area, layers of highly colored sands, red, brown, blue, purple, yellow and white, appear in gorgeous terrace, mesa, hill and mound formations, and are viewed advantageously from the Painted Desert Rim Drive.

In the Blue Forest are badland erosional forms cut into the deep velvet blue and maroon shales which differentiate this particular area. Unusual pink-colored wood occurs here, and many logs may be seen in place embedded in the sandstone and in various degrees of resurrection and disintegration. Occasional pieces of fossil bones of prehistoric monsters are scattered on the ground.

For nearly 50 years, the Agate Bridge has been called "The most celebrated petrified log in the world." It spans a 40-foot arroyo carved in the white sandstone beneath to a depth of about 30 feet. The complete log is about 110 feet long and about four feet through at the base.

The First Forest, containing hundreds of practically intact specimens, is enhanced by the presence of a surrounding fringe of fantastic erosional forms. The attractive landscape is covered with fragments and large sections of highly colored agatized wood.

The Second Forest contains the finest examples of white and gray petrified wood together with an abundance of large, agatized and quartz-bejeweled logs.

The Third Forest covers the largest area and the logs are more concentrated and longer, as a rule, than in the other forests. The Agate House, a prehistoric Indian pueblo, is located in this forest.

The Rainbow Forest is comprised of innumerable petrified logs, unequalled in intrinsic design and brilliance of color. In a compact unit, it contains the famous Resurrection Log, Old Faithful, and many others. Old Faithful is one of the largest logs in the Monument. In the Rainbow Forest Museum are brilliantly polished sections of petrified wood showing all the colors of agate, chalcedony, jasper and onyx, form all parts of the Monument.

Information contained in this article from United States Department of the Interior Guide to the Petrified Forest National Monument, published by the National Park Service.

Some especially beautiful specimens of petrified logs in Arizona's Petrified Forest, which contains the largest number of such trees to be found on earth. The story of how nature created these semi-precious stone logs is fascinating-the process that changed this region from a forested land into the Painted Desert region. Josef Muench Kodachrome

Once a semitropical jungle of coniferous trees, rushes and ferns, inhabited by great reptiles and amphibions, river floods covered the region, with layers of mud and sand. Trees and bones absorbed minerals, turned to stone. Mountains uplifted the region, erosion cutting across many colored beds of shale and sandstone, producing "the Painted Desert".