Petrified Forest National Park

Geology

Erosion has sculpted and shaped the intriguing landforms at Petrified Forest National Park

Erosion has sculpted and shaped intriguing landforms. The rocks reveal an enthralling chronicle of time that is unfolding and ever-changing. What can the rocks tell us? Think of the colorful layers as pages in a massive book.The first chapter of this geological text is the Chinle Formation.

Chinle Formation

The Chinle Formation was deposited over 200 million years ago during the Late Triassic Period. The colorful badland hills, flat-topped mesas, and sculptured buttes of the Painted Desert are primarily made up of the Chinle Formation, mainly fluvial (river related) deposits. Within Petrified Forest National Park, the Chinle Formation is further divided to include the Blue Mesa Member, the Sonsela Member, the Petrified Forest Member, and the Owl Rock Member.

Members Oldest to Youngest
The Mesa Redondo Member is the oldest member of the Chinle Formation exposed in the Petrified Forest, mainly in the Tepees area. The Mesa Redondo consists of dark red siltstones as well as sandy conglomerates. The top of the member is very colorful hard layer with yellow, red, and purple mottles. The Mesa Redondo was deposited between 225-227 Million years ago and represents floodplain deposits that were adjacent to the sandstone channels of the Shinarump Member.

The Blue Mesa Member consists of thick deposits of grey, blue, purple, and green mudstones and minor sandstone beds, the most prominent of which is the Newspaper Rock Sandstone. This unit is best exposed in the Tepees area of the park. The Blue Mesa Member is approximately 220-225 million years old.

The Sonsela Member is divided into three parts: 1) the upper Flattops One Bed, which consists of a thick cliff-forming brown, cross-bedded sandstone, 2) the middle Jim Camp Wash Beds of blue, grey, and purple mudstones and numerous small grey and white sandstone beds, and 3) the lower Rainbow Forest bed consisting of white cross-bedded sandstone and conglomerate of rounded pebbles and cobbles which contains the logs of the Rainbow Forest. This sandstone caps Blue Mesa, Agate Mesa, and the mesa north of the Rainbow Forest. The Sonsela Member is approximately 216 million years old.

The Petrified Forest Member consists of thick sequences of reddish mudstones and brown sandstone layers. This member is exposed in the Flattops and is the white and pink reworked volcaniclastic unit of the Painted Desert. It contains large amounts of petrified wood. The Black Forest Bed, part of the Petrified Forest Member north of Kachina Point, has been dated isotopically at 213 +/- 1.7 million years old.

The Owl Rock Member consists of pinkish-orange mudstones mixed with hard, thin layers of limestone. Lenses of selenite gypsum are scattered periodically throughout the Owl Rock Member representing the minerals left behind after evaporation of inland lakes. This member is exposed on Chinde Mesa at the northernmost border of the park. The Owl Rock Member is approximately 205 million years old.

The colorful layers in the Chinle Formation represent ancient soil horizons. The coloration is due to the presence of various minerals. While the red and green layers generally contain the same amount of iron and manganese, differences in color depend on the position of the groundwater table when the ancient soils were formed. In soils where the water table was high, a reducing environment existed due to a lack of oxygen in the sediments, giving the iron minerals in the soil a greenish or bluish hue. The reddish soils were formed where the water table fluctuated, allowing the iron minerals to oxidize (rust).

Bidahochi Formation
During the Late Miocene and Early Pliocene Epochs of the Neogene Period (4-8 million years ago) a large lake basin with ephemeral lakes covered much of Northeastern Arizona. Fine-grained fluvial and lacustrine (lake related) sediment such as silt, clay, and sand represent the lower part of the Bidahochi Formation. Volcanoes, both nearby and as far as the Southwestern Nevada Volcanic field, spewed ash and lava over the land and into the basin. Many of the volcanoes were phreatomagmatic, when ground or lake-water mingled with eruptive material (magma) to cause explosive eruptions. The resulting ash formed fine-grained deposits that were deposited within the lake sediments.

After a few million years of erosion, most of the Bidahochi Formation has been removed from the park area, leaving volcanic scoria cones and maars (flat-bottom, roughly circular volcanic craters of explosive origin). The vent from one of these maars is exposed on the Painted Desert Rim across the park road to the east of Pintado Point. The Hopi Butte Volcanic Field, which can be seen from the northern overlooks of the park extending northwest, is considered one of the largest concentrations of maar landforms in the world, covering about 965 square miles (2,500 square km). The erosion-resistant lava flows, such as Pilot Rock and the Hopi Buttes, protect the softer lake-bed deposits beneath.

Where the Bidahochi and Chinle Formations make contact is an unconformity. An unconformity represents missing rock layers which in turn represents missing time. It’s like a geology textbook with missing pages. You can tell that a page is missing but you can’t tell what was on them. The Chinle Formation was deposited over 200 million years ago but the Bidahochi Formation is only about 8 million years ago. The contact between the Bidahochi and Chinle Formations represents 192 million years of missing time!

Pleistocene and Holocene Sediments
Pleistocene and Holocene Epoch (1.8 million years ago to present) deposits of windblown sand and alluvium (deposited by flowing water), now cover much of the older formations of the park. At higher elevations in the northern part of the park, 500,000-year-old dunes can be found. Younger dunes, around 10,000 years old, are found in drainage areas that contain sand such as Lithodendron Wash. The youngest dunes are found throughout the park, in all settings, deposited around a thousand years ago. These dune deposits are largely stabilized by vegetation, especially grasses. While not as numerous as the fossils of the Chinle Formation, fossils have been found even in the quaternary sediments, including fragments of an ancestral proboscidean (elephants and their relatives, such as mammoths). The Little Colorado River and its tributaries, including the Puerco River, have cut their own valleys into the soft Chinle and Bidahochi Formations of the Painted Desert.

see original article here: https://www.nps.gov/pefo/learn/nature/geologicformations.htm

Native American History

Home of Folsom, Clovis, and later Paleoindians peoples

Paleoindian
13,500 to 6,000 BCE
At the end of the last Ice Age, the Southwest region was very different than today: higher rainfall, cooler average temperatures, green grasslands, wooded river bottoms. Paleoindians were highly mobile groups who gathered food and hunted large animals like mammoth and bison. They found the Petrified Forest area a highly attractive, resource-rich setting.

Paleoindian groups are known for their large, well-made projectile points used for hunting game. At Petrified Forest, the people used petrified wood to create a range of different types of stone tools. Early Paleoindian groups, with their distinctive elegant fluting of projectile points, help define the Clovis and Folsom Cultures of these ancient people. Folsom, Clovis, and later Paleoindian camps have been found within Petrified Forest National Park.

Archaic
6,000 to 500 BCE
The post-Ice Age climate became warmer and dryer, causing megafauna like the mammoth to go extinct. People had to broaden their food sources to include many different species of plants and animals. Though still mobile, they decreased how far they moved around the landscape. The decreased mobility and wider range of food sources set the stage for domesticating plants and animals. At the end of the period, corn was introduced from further south, starting a dramatic change in how people lived. Artifacts of this period are more diverse, including stone tools as well as one-handed manos and basin metates used to grind maize.

Basketmaker
500 BCE to 650 CE
By this period the park’s climate had become similar to what we experience today. The Basketmaker people built more permanent villages consisting of slab-lined pit houses. They focused on farming, growing corn, squash, and eventually beans. But the remains of small game (such as rabbits) show further diversity in their diet.

Sivu’ovi is the largest known Basketmaker II village in the park, consisting of at least 47 pit houses and numerous storage pits. It is currently thought that Sivu’ovi was occupied seasonally, when the surrounding lands could be farmed. Artifacts found there include Adamana Brown-style pottery, some of the earliest ceramics in northern Arizona.

Pueblo I
650 to 950 CE
The transition into Pueblo Periods shows that people were becoming even more fixed to one place on the landscape. People began to build more substantial above-ground structures, moving out of their pit houses and into the clusters of stone structures we call pueblos.

The use of ceramics for cooking and storage was very important. Today, these are the most common artifacts found at Pueblo sites. Ceramics changed from plain brown and gray vessels to corrugated varieties for cooking and storage, and more decorative types with intricate black-on-white designs.

Pueblo II-III
950 to 1300 CE
The Pueblo II and III periods span momentous times in the Southwest. The settlement at Chaco Canyon ushered a sphere of influence that spanned the Four Corners region, marked by increased village sizes, new architecture, and introduction of ceremonial kivas.

Ceramics during this period show increased diversity of designs, going from corrugated and black-on-white pottery to black-on-red and polychrome pottery as well. At Petrified Forest, the use of petrified wood as a building material became popular, creating the “agate houses” throughout the park.

Pueblo IV
1300 to 1540 CE
The Petrified Forest lies at the crossroads of major migration and trade routes along the Little Colorado and Puerco Rivers. This leads to an unparalleled diversity of ceramic types dating to this period. Types have been traced to groups hundreds of miles away throughout Arizona, New Mexico, and Utah.

Puerco Pueblo, founded during the Late Pueblo III period, is a fine example of a large village of its time. Consisting of over 100 rooms located on the banks of the Puerco River, it probably had a population of around 200 people. The inhabitants farmed along the flood plain and traded with their neighbors up and down the river. Puerco Pueblo and the Petrified Forest area were largely depopulated in the early 1400s due to a long standing drought that affected the agricultural-based settlements. The park was never fully abandoned, but there was a large movement of people to nearby larger population centers (Zuni and Hopi, for example).

The end of this period in the Southwest coincides with the arrival of Spanish explorer Francisco Vazquez de Coronado. His was the first European expedition to see the Grand Canyon and Colorado River.

see original article here: https://www.nps.gov/pefo/learn/historyculture/paleo-people.htm

Park History

How Petrified Forest became a National Park

Spanish Exploration
Standing at the edge of a colorful sea of badlands and mesas, a Spanish explorer named the region El Desierto Pintado–the Painted Desert–or so the story goes. No mention was made of petrified wood, but the Spanish of the 1500-1700s were focused on finding routes between their colonies along the Rio Grande and the Pacific Coast. Within Petrified Forest National Park, Spanish inscriptions have been discovered from the late 1800s, descendents of some of the earliest non-American Indian settlers in the region.

Whipple Expedition of 1853
After the Southwest became part of U.S. territories in the mid-1800s, the U.S. government continued to seek routes to the Pacific. U.S. Army Lt. Amiel Whipple led a route survey along the 35th parallel. Impressed with the Painted Desert landscape, Whipple named the seasonal river lined with petrified wood deposits Lithodendron (“stone tree”) Creek–the large wash that bisects the Painted Desert Wilderness Area today. The Whipple Expedition crew provided the first published account of petrified wood in what would become Petrified Forest National Park.

E. F. Beale and the U.S. Camel Corps
Can you picture a camel caravan at the edge of the Painted Desert? Experienced explorer, frontiersman, and retired military officer Edward F. Beale was hired by the U.S. Government to survey and build a wagon road following Whipple’s route along the 35th parallel. Between 1857 and 1860, Beale made several trips, building and improving the road. As part of a government experiment in desert transport, Beale used camels as pack animals. Though Beale became convinced of the camels’ value, the government did not choose to invest in camels. The old wagon road is still visible in spots across the Southwest, and part of it is on the National Register of Historic Places.

Homesteading
In the late 1800s, pioneers and private stage companies followed the routes of the 35th parallel and began to further settle the area. Homesteaders developed ranches that took advantage of the rich grasslands, which would forever after bear the mark of grazing. In 1884, the Holbrook Times noted: “…The whole northern portion of the territory seems to be undergoing a great change….Our plains are stocked with thousands of cattle, horses and sheep…” Cattle grazed in Petrified Forest until the mid-1900s. Some private ranches still neighbor park lands.

see original article here: https://www.nps.gov/pefo/learn/historyculture/explorerssettlers.htm

Attractions

The best things to do at Petrified Forest National Park

Many people don’t realize how much there is to do at Petrified Forest National Park! There is something to interest everyone here. Be sure to check our Calendar to see if something special is happening the day you will be here.

Hit the Road
A good starting point is a drive through the park, stopping at some of the overlooks.

Hit the Trail
There are maintained trails in the park that highlight topics like archeology, natural environments, and the famous petrified logs.

Hiking
The adventurous hiker will love wandering off trail in the Petrified Forest. For those that want guidance we have Off the Beaten Path routes as well.

Backpacking
Hiking and camping in the Petrified Forest National Wilderness Area is a great opportunity for solitude and adventure. Enjoy colorful sunsets, the incredible night sky, and inspiring sunrises.

Bicycling
The park road is great for exploring, but there are a few other routes you can take by bike.

Horseback Riding
Play cowboy! Enjoy a ride in the park–BYOH (bring your own horse!)

Geocaching

This worldwide game—or other similar pastimes—of hiding and seeking treasure can be played in some national parks, including Petrified Forest!

Guided Tours
Join a ranger—or scientist, volunteer, cultural demonstrator, reenactor, or other field expert—for a guided activity.

Dogs and Other Critters
Enjoy the park with your furry (feathered, scaled or…) friend or family member!

Visitor Centers and Exhibits
Stop at Painted Desert Visitor Center, Painted Desert Inn National Historic Landmark, and the Rainbow Forest Museum to plan your visit, ask questions, get your Junior Ranger booklet, and discover exhibits.

see original article here: https://www.nps.gov/pefo/planyourvisit/things2do.htm

Vegetation

Not all plants at Petrified Forest National Park are fossils

Not all plants at Petrified Forest National Park are fossils. Living plants are critical components within the grassland ecosystem found throughout the park. Plants capture particulate dust in the air, filter gaseous pollutants, convert carbon dioxide to oxygen, provide habitat for animals, and supply raw materials for humans.

Trees and Shrubs

Wildflowers

Cactuses

Grasses, Reeds, Rushes, and Sedges

Mosses, Ferns, and Allies

Lichens

Plant Adaptations

Plants of arid climates have adaptations which enable them to survive the extremes of temperature and precipitation. These adaptations can be grouped in two basic categories, drought escapers and drought resistors.

Escape
Drought escapers are plants which take advantage of favorable growing conditions when they exist, but go dormant when those conditions disappear. They are usually annuals, growing only when enough water is available. Seeds produced under good conditions can lie dormant for years if conditions are not favorable for germination. Most grasses and wildflowers are drought escapers.

Resistance
Drought resistors are typically perennials. They have mechanisms for reducing the damage a drought can cause. For example, some will drop their leaves if water is unavailable. Many have small, hairy leaves which reduce exposure to air currents and solar radiation and thereby limit the amount of water lost to evaporation.

Cacti, yuccas and mosses are examples of drought resistors. Yuccas have extensive taproots which can reach water beyond the ability of other plants. Mosses can tolerate complete dehydration. When rains return after extensive dry periods, mosses green up immediately.

see original article here: https://www.nps.gov/pefo/learn/nature/plants.htm

Animal Life

There is an abundance of wildlife at Petrified Forest National Park

Animal life at Petrified Forest includes amphibians, birds, insects, spiders, mammals, and reptiles. Birds, lizards and rabbits are seen most frequently, though seasons and weather play a large role in determining what animals are active.

For many animals, activity occurs during a particular temperature range. Crepuscular animals are active at dawn and dusk, the coolest times of day. The half-darkness makes prey animals less visible, yet visibility is good enough to locate food.

Activity can change with the season, too. Snakes and lizards are diurnal (active during the day) in late spring and early fall, but they become crepuscular during the heat of summer.

Many animals in the park are nocturnal (active at night). This is an adaptation not only to avoid high summer daytime temperatures, but also to avoid certain predators.

You are much more likely to see animal life in the park if you come as early as park hours allow and stay as late as allowed. These are also the times when the angle of the sun makes the views and colors of the Painted Desert most spectacular.

Whenever you are in a national park, do not approach, feed, or harass any wildlife. Help your parks reduce the impact of human visitors to the homeland of many wild species.

see original article here: https://www.nps.gov/pefo/learn/nature/animals.htm

Hiking Trails

The best hiking trails at Petrified Forest National Park

Looking for an off-trail adventure? You can hike throughout the park, as long as you are safely and legally parked. (While in developed hiking areas, stay on designated trail though.)

Off the Beaten Path
Backcountry hiking offers the opportunity to visit sites seldom seen by most visitors. Check out the “Off the Beaten Path” suggested routes. Some destinations are found off an old road or trail no longer maintained; others may require route finding skills.

Wilderness Area
Designated Wilderness Areas are protected and valued for their untrammeled, natural, undeveloped, and secluded qualities. The Petrified Forest National Wilderness Area was one of the first to receive this designation in the National Park System. The Wilderness Act (and our designated Wilderness Area) celebrated its 50th anniversary in 2014. Learn more about what it means to be designated Wilderness.

The Petrified Forest National Wilderness Area that has two units: one in the north allowing hikers to roam the red and orange part of the Painted Desert; and one in the south showcasing highly eroded landscapes, badlands, and petrified wood.

Camping
Go to the Backpacking page to learn about spending the night in the Wilderness Area.

Wilderness Recreation Information
No permits are required for day hiking (except for Devils Playground). Day hikers must be back at their vehicles by the park’s posted closing time.
A permit for camping is required for overnight use and can be obtained on the day of activity.
Be prepared! There is no water and little shade in the backcountry.
Follow Leave No Trace principles
Motorized vehicles and bicycles are not allowed in Wilderness.
Horses and other pack animals are allowed in Wilderness.

While exploring outdoors, it is tempting to take a small piece of petrified wood, but remember removal of petrified wood or other natural and cultural artifacts found in the park is prohibited by law. Gift shops inside and outside the park sell petrified wood collected from private land outside the park boundaries.

see original article here: https://www.nps.gov/pefo/planyourvisit/hiking.htm