Petrified Forest National Park was first established as a National Monument on 08 Dec 1906 when Teddy Roosevelt signed the proclamation. Congress passed a bill that elevated the monument into a national park in 1962.
Size and Visitation
Acreage - as of September 23, 2000
Federal Land - 93,532.57
Non-Federal Land - 0.00
Gross Area Acres - 93,532.57
About one half of the visitation occurs during June, July and August. The visitation for 1996 was 829,615. Visitation for 1999 was 666,978.
This high dry tableland was once a vast floodplain crossed by many streams. To the south, tall, stately pine-like trees grew along the headwaters. Crocodile-like reptiles; giant, fish-eating amphibians; and small dinosaurs lived among a variety of ferns, cycads, and other plants and animals that are known only as fossils today. The tall trees, Araucarioxylon, Woodworthia and Schilderia, fell and were washed by swollen streams into the floodplain. There they were covered by silt, mud, and volcanic ash, and this blanket of deposits cut off oxygen and slowed the logs' decay. Gradually silica-bearing ground waters seeped through the logs, bit by bit, encased the original wood tissues with silica deposits. Slowly the process continued, the silica crystallized into the mineral quartz, and the logs were preserved as petrified wood.
That was about 225 million years ago in the late Triassic. After that time, the area sank, was flooded, and was covered with freshwater sediments. Later the area was lifted far above sea level, and this uplift created stresses that cracked the giant logs. Still later, in recent geological time, wind and water wore away the gradually accumulated layers of hardened sediments. Now the petrified logs and fossilized animal and plant remains are exposed on the land's surface and the Painted Desert has its present sculpted form.
Today the ever present forces of wind and water continue to remove sediments. Erosion continues to break down the giant logs and reach for the logs and other remaining fossils still buried below the surface. In some places, up to 300 feet (90 meters) of fossil-bearing material remains. The petrified logs, and other fossils of plants and creatures that lived in the area, and the rocks locking them in places all testify to changed in the environment through millions of years.
The Painted Desert is an expanse of badland hills, flat-topped mesas and buttes. It is an arid land, sparsely vegetated and heavily eroded. The name Painted Desert refers to the rainbow of colorful sedimentary layers exposed in the austere landscape. It is represented by outcroppings of the Late Triassic Period Chinle Formation.
The Painted Desert is a narrow, crescent shaped arc, about 160 miles long which begins about 30 miles north of Cameron near Grand Canyon, and swings southeast just beyond Petrified Forest National Park. This arc varies in width from 10 miles wide in the Cameron area to about 35 miles wide at Petrified Forest. The Little Colorado River cradles the southern edge and the tableland of Hopi Mesas and buttes make up the northern boundary.
The landforms of the Painted Desert have been described as a multicolored layer cake. The variety of hues in the sandstone and mudstone layers of the Chinle Formation is the result of the varying mineral content in the sediments and the rate at which the sediments were laid down. When sediments are deposited slowly, oxides of iron and (hematite) aluminum become concentrated in the soil. These concentrations create the red, orange, and pink colors you see at the north end of the park. During a rapid sediment buildup such as a flooding event, oxygen is removed from the soil forming the blue, gray, and lavender layers. You will see these colors as you travel through the southern portion of the park.
Wind and rain, sedimentary composition of the rocks and the lack of protective vegetative, all contribute to rapid erosion of the Chinle Formation. Torrential rains of the Arizona monsoon hasten the erosion of the soft mudstone by cutting deep, narrow gullies into the steep slopes of the hills and the soft, rounded hilltops seem to melt as the soil is washed from the tops. As you drive through the park, you will notice that some of the clay hills have a layer of resistant sandstone, conglomerate or basalt on the top. These hills erode at a substantially decreased rate. Similarly, where well-developed vegetation grows, erosion is slowed. Erosion studies indicate that steep slopes may loose as much as 1/4 inch of soil a year. That small amount may seem insignificant, but geologically it is very rapid; each century one to two feet of surface material erodes away.
Have you heard the saying "Take only pictures and leave only footprints?" In the Painted Desert, even a footprint may cause damage. Although sparse, plant life helps stabilize the easily eroded soils. One of the more important and least recognized plant communities in this area is cryptobiotic soil. This plant community represents up to 70% of the living ground cover. These living crusts are comprised of cyanobacteria, lichens, mosses, green algae, microfungi, and bacteria. With rainfall they can swell up to ten times their dry size and serve to capture and store water. Cryptobiotic soils do not look like plants, but have a blackened crust-like appearance. People, unaware of what they are walking on, often crush these plant communities and cause damage that will take years to regrow.
Imagine a large basin area with numerous rivers and streams flowing through lowland. A lush landscape with coniferous trees up to nine feet in diameter and towering almost two hundred feet tall surrounds you. Ferns, cycads and giant horsetails grow abundantly along the waterway, providing food and shelter for many insects, reptiles, amphibians, and other creatures.
During the Triassic Period (200 - 250 million years ago) the Colorado Plateau area of northeastern Arizona was located near the equator and on the southwestern edge of the landmass known as "Pangea". (Eventually this super-continent separated to create our present continents.) This tropical location resulted in a climate and environment very different from today. Fossil evidence of this ancient land lies in the sediments called the Chinle Formation that is now exposed in Petrified Forest National Park.
Over time, trees died or perhaps were knocked over by floodwaters or wind. Rivers carried the trees into the lowlands, breaking off branches, bark, and small roots along the way. Some trees were deposited on the flood plain adjacent to the rivers and others were buried in the stream channels. Most of the trees decomposed and disappeared. But a few trees were petrified, becoming the beautiful fossilized logs we see today. Most of the fossilized logs are from a tree called Araucarioxylon arizonicum. Two others, Woodworthia and Schilderia, occur in small quantities in the northern part of the park. All 3 species are now extinct.
Some logs were buried by sediment before they could decompose while volcanoes to the west spewed tons of ash into the atmosphere. Winds carried ash into the area where it was incorporated into the deepening layers of sediment. Ground water dissolved silica from the volcanic ash and carried it through the logs. This solution filled, or replaced cell walls, crystallizing as the mineral quartz. The process was often so exact that replacement left a fossil that shows every detail of the logs� original surfaces and, occasionally, the internal cell structures. Iron rich minerals combined with quartz during the petrification process, creating the brilliant rainbow of colors.
Over time, this area has endured many changes. About 60 million years ago, after the Chinle Formation was deeply buried by younger strata, the region was uplifted as part of the massive Colorado Plateau. As time passed, many rivers and storms eroded the land, removing the layers of rock until, again, the Chinle Formation was exposed. Now fossilized logs lie strewn across the clay hills and are exposed in cliff faces. Most logs are broken into segments. Humans did not cut the logs. Because the sections are still in order, we know that the logs fractured after they were buried and the petrification process was complete. Since petrified logs are composed of quartz, they are hard and brittle and break easily when subjected to stress. Earthquakes or the gradual lifting of the Colorado Plateau may have produced such stress.
Petrified wood is found in every state and in many countries, so why was this place made a national park? It was originally established to protect some of the largest and most beautifully preserved concentrations of petrified wood in the world. We now know, however, that few places in the world have a fossil record of the Triassic Period that is so diverse and complete. These things make this park special.
Today all natural and cultural resources such as petrified wood, rocks, fossils, artifacts and plants must not be disturbed or removed. Unfortunately, in spite of severe penalties, written and verbal warnings and the opportunity to legally obtain petrified wood, thoughtless visitors continue to steal over one ton each month. (Petrified wood sold in local shops does not come from the park. It is obtained from private lands outside the park boundaries.)
Sites throughout the park tell of human history in the area for more than 2,000 years. We don't know the entire story, but there were separate occupations, a cultural transition from wandering families to settled agricultural villages, pueblos, and trading ties with neighboring villages. Then this story of early people, told by potsherds, rubble, and pictures on the rocks, fades around 1400 AD.
In the mid-1800's US Army mappers and surveyors came into this area and carried back East stories of the remarkable "Painted Desert and its trees turned to stone." Next, farmers, ranchers, and sightseers made their ways into the area. After a period of using the wood for souvenirs and numerous commercial ventures, territorial residents recognized that the supply of petrified wood was not endless. In 1906 selected "forests" were set aside as Petrified Forest National Monument. In 1932 some 1,000 hectares (2,500 acres) more of the Painted Desert were purchased and added to the monument. In 1962 the area became Petrified Forest National Park, and in 1970, 20,250 hectares (50,000 acres) were further set aside as wilderness.
The first historic record of petrified wood in this region came from a US Army officer who found it near today's Canyon de Chelly National Monument, Arizona. Abundant deposits were recorded south of the present Petrified Forest National Park in the 1850's. By 1900, removal of the wood led to calls for preserving areas with large deposits of it. The park exists for this purpose and there is no collecting or giving out of samples permitted. Petrified wood can be bought from commercial dealers who collect it from outside the park. The commercial wood is from the same geological deposits and of the same quality as the wood found in the park. Small pieces are sold, rough, tumbled, or polished. Artists and craftspeople work larger pieces into decorative objects. Jewelry, bookends and clocks are popular sales items. Minerals and impurities deposited while the wood was petrifying add the bright colors and interesting patterns.
The distinctive white layer interrupting the reddish base is sandstone. The cap of the Tepees is clay. Dark layers are caused by high carbon content. The darker red is iron-stained siltstone. The iron oxide is hematite. The reddish base is stained by iron oxide.
Thousands of prehistoric petroglyph sites are scattered throughout the southwestern U.S. on cliffs, boulders and cave walls. These images are composed of petroglyphs (rock carvings) and pictographs (rock paintings). For the vast majority of sites, the meanings and functions of these drawings have been lost. During the last 16 years, Bob Preston working largely in Petrified Forest National Park, has shown convincingly that many of these sites were used as "solar calendars" to track the yearly movement of the sun across the sky through the interplay of sunlight on the petroglyph. As long as time has not altered the alignments or surfaces of the rocks involved, these solar calendars function the same today as they did when they were created almost a thousand years ago.
When the Spanish explorer Coronado first came through this part of Arizona in 1540, it was essentially uninhabited. However only a few hundred years earlier, subsistence farmers, belonging to principally the Ancestral Pueblo People culture, occupied 600 known sites in the park. By 1450 A.D. they had moved away. Descendants of these early residents of Petrified Forest might be found in the historic pueblos in the surrounding region, the Hopi pueblos about 100 km to the northwest or the Zuni pueblos about 70 km to the east in western New Mexico.
Most petroglyph sites in the park date from about 1000-1350 A.D. The petroglyphs are primarily geometric designs with several basic design elements appearing frequently, especially spirals and circles. Petroglyphs were made by pecking away the dark surface (desert varnish) of the rock to reveal the lighter underlying rock, generally sandstone. Petroglyphs in Petrified Forest National Park are some of the best preserved in the Southwest, and provide an excellent source for scientific study.
Since the first European encounters with the indigenous Southwest pueblo cultures in the sixteenth century, there is no historic record to indicate that the descendants of the early pueblo cultures monitored the motion of the sun, moon and stars to regulate ceremonial and agricultural calendars, as is common in many pretechnological cultures.
The earth's equator is tilted with respect to its orbit about the sun by an angle of 23.4 degrees. Hence, on one side of the orbit the sun is over the northern hemisphere, reaching maximum latitude of 23.4 degrees on the summer solstice, while on the other side of the orbit the sun is over the southern hemisphere, reaching minimum latitude of 23.4 degrees. Therefore, the sun follows different paths in the sky throughout the year. In the summer the sun follows a very high path in the sky, with the highest track reached on summer solstice, usually June 21st (or December 21st in the summer hemisphere). In winter the sun follows a very low path, with the lowest track reached on winter solstice, usually December 21st (or June 21st in the southern hemisphere). Since the sun is in different positions during the year, the sunlit images (or shadows) it casts on rock faces are also in different positions at different times of the year. At the two solstices the sun reaches the highest and lowest points in the sky, and the sunlit images on the rock faces also reach their maximum positions on these dates. In March and September the sun is over the equator and its track is midway between the solstice tracks; these dates are known as eqinoxes.
Most people know that there are longer days in June than in December, and some may notice that the sun's sunrise and sunset positions are changing. In June the sun rises in the northeast and sets in the northwest, and in December the sun rises in the southeast and sets in the southwest. Since the angle between the earth's equator and its orbit changes slowly (about a tenth of a degree per 1000 years), the path of the sun on the solstices (or any other day of the year) is almost precisely the same as it was on that day the previous year (or even 1000 years ago). The tracks of shadows cast by the sun on rocks on a particular day also remain the same year after year (as long as the rocks don't move or erode).
In 1977 a spiral petroglyph at Chaco Canyon National Monument was discovered which displayed a precise interaction with sunlight at the time of summer solstice by means of a narrow shaft of sunlight that moved down a shadowed rock face to bisect the center of a large spiral petroglyph. Subsequent observations found that on winter solstice and equinoxes there were intriguing interactions of sunlit shafts with the large spiral and a smaller spiral nearby. No other example of a sunlight interaction with prehistoric or historic petroglyphs was known at this time. However, there was a tradition of Pueblo sun watching in historic times, particularly of the varying sunrise and sunset positions throughout the year, to set the dates for ceremonies.
As a result of the Chaco Canyon find, Bob Preston initiated a research project to determine whether other petroglyph sites in the Southwest functioned as solar "observatories." Over the last 16 years he has identified about 120 examples of similar solstice events at more than 50 petroglyph sites in Arizona, New Mexico and southern Utah. Evidence indicates that the phenomenon may have been spread over as much as a 1000-km region. These findings show clearly that certain petroglyphs were used by early pueblo cultures to function as calendrical markers for the winter and summer solstices. Petrified Forest National Park contains the greatest known concentration of solar calendars, with 16 of the sites being in or immediately adjacent to the park, and has been key to understanding their nature.
Shadows and sunlit images are found to move across petroglyphs due to other rocks being in the path of the sun's rays. As the sun's path across the sky changes throughout the year, the positions of the shadows and sunlit images change on the petroglyph panels. In many cases the petroglyphs have been placed on the rock faces in just the right position so that specific interactions occur on the solstices. The most common types of petroglyphs on which solsitial interactions have been identified are spirals and circles. The key to determining that these were intended and not by chance is that interactions are seen from site to site, and occur on the solstices more frequently than on other days of the year. These consistent interactions may involve a point of sunlight or shadow piercing the center or tracing the edge of a spiral or circular petroglyph; or shadow lines may suddenly appear or disappear at the center or edges of the petroglyph; or they may move up to the center or edge and then retreat. It is not uncommon for a single petroglyph to display multiple interactions of this type, either on the same solstice or on each of the solstices. In fact, at one site, there are five circular and spiral petroglyphs that show 15 interactions on the both solstices.
An intriguing question is whether types of petroglyph images were involved with specific dates. In several cases similar sunlight and shadow interactions occur on spiral and circular petroglyphs on the equinox, and distinctive interactions occur with other petroglyphs on the solstices and other dates. Clearly much of the puzzle remains to be unraveled.
This interdisciplinary research, linking the disparate fields of astronomy, archaeology and art, opens up a previously untapped source of archaeological data in the Southwest. The observed interplay of sunlight and petroglyphs are "slow motion movies" that have survived for a thousand years, providing a window into the ceremonial lives of these early people. Visitors to Petrified Forest National Park can visit Puerco Pueblo and experience the wonder of a functioning solar calendar during the ten-day periods proceeding or following the summer solstice.
Petroglyphs were pecked on exposed surfaces of boulders covered with "desert varnish." Desert varnish is a thin coating of iron or manganese, bacteria and other organic deposits, which slowly builds up on the rock surface, growing darker and harder with time. This dark layer provided the contrast to exhibit pecked figures.
Petroglyphs were made using two techniques. A direct blow to the surface of the boulder with a hand-sized hard, rounded rock called a hammer-stone removed the boulder's darkened surface but did not allow control in placing the peck mark. If a hammer-stone was used in conjunction with a chisel, however, greater control could be exercised, resulting in a superior effect.
To assure their figures were well drawn, they lightly pecked a preliminary outline. You sometimes see these outlines pecked on a rock. Solid figures tend to be smaller because of the greater amount of work involved, while outline figures may approach life size.
Interpretation of these figures is usually impossible. Petroglyphs may commemorate important events, facilitate record keeping, mark clan or other territorial boundaries and migrations, document natural events such as the summer solstice, or some may be doodles.
Determining the age of petroglyphs is difficult. Archaeologists might: assign an age which correlates with a nearby habitation site; evaluate the subject matter and style to determine how it relates to a specific time period; compare the sequence of design layering; or use technical dating techniques such as radiocarbon dating.
Archaeologists have categorized petroglyphs found in the park into six groups: anthropomorphs, zoomorphs, kachinas, hands\tracks, geometrics, and indeterminate.
Anthropomorphs and Kachinas represent the human form. Anthropomorphic figures may have complete bodies but generally lack facial features. Kachinas often take the form of heads or masks and most have facial features.
Zoomorphs include large and small animals, reptiles, and birds. Look closely and you will see cougars, birds, lizards, snakes, bats, coyotes, and rabbits on petroglyph panels at Petrified Forest.
Hands and tracks include bear paws, bird tracks, cloven hooves and human feet or handprints. Some human tracks even appear in pairs.
Geometrics consist of textile and pottery designs, spirals, circles, and other geometric shapes. You will see many of these elements at Puerco Pueblo and Newspaper Rock.
A variety of factors contribute to the erosion of petroglyphs including natural forces such as wind, rain, extreme temperatures, plant growth and rock type. The most devastating factor however, is humans. The removal of petroglyphs from public lands for souvenirs, and the defacement and vandalism that frequently occur must be stopped. Join Petrified Forest National Park in protecting and preserving these remarkable treasures. Please stay on the trail and remember, even the touch of your hand can eventually contribute to their destruction.
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