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.
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.
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.
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.
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.
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.