Petrified Forest National Park
Petrified Forest National Park is located in Navajo and Apache
counties in Arizona. The park's headquarters are about 26 miles
east of Holbrook along I-40, which parallels a railroad line,
the Puerco River, and historic U.S. Route 66, all crossing the
park roughly east–west. Named for its large deposits of
petrified wood, the park covers about 146 square miles,
encompassing semi-desert shrub steppe as well as highly eroded
and colorful badlands. The site, the northern part of which
extends into the Painted Desert, was declared a National
Monument in 1906 and a national park in 1962. About 600,000
people visit the park each year and take part in activities
including sightseeing, photography, hiking, and backpacking.
Averaging about 5,400 feet in elevation, the park has a dry
windy climate with temperatures that vary from summer highs of
about 100 °F to winter lows well below freezing. More than 400
species of plants, dominated by grasses such as bunchgrass, blue
grama, and sacaton, are found in the park. Fauna include larger
animals such as pronghorns, coyotes, and bobcats; many smaller
animals such as deer mice; snakes; lizards; seven kinds of
amphibians, and more than 200 species of birds, some of which
are permanent residents and many of which are migratory. About
half of the park is designated wilderness.
The
Petrified Forest is known for its fossils, especially fallen
trees that lived in the Late Triassic, about 225 million years
ago. The sediments containing the fossil logs are part of the
widespread and colorful Chinle Formation, from which the Painted
Desert gets its name. Beginning about 60 million years ago, the
Colorado Plateau, of which the park is part, was pushed upward
by tectonic forces and exposed to increased erosion. All of the
park's rock layers above the Chinle, except geologically recent
ones found in parts of the park, have been removed by wind and
water. In addition to petrified logs, fossils found in the park
have included Late Triassic ferns, cycads, ginkgoes, and many
other plants as well as fauna including giant reptiles called
phytosaurs, large amphibians, and early dinosaurs.
Paleontologists have been unearthing and studying the park's
fossils since the early 20th century.
The park's earliest human inhabitants arrived at least 8,000
years ago. By about 2,000 years ago, they were growing corn in
the area and shortly thereafter building pit houses in what
would become the park. Later inhabitants built above-ground
dwellings called pueblos. Although a changing climate caused the
last of the park's pueblos to be abandoned by about 1400 CE,
more than 600 archeological sites, including petroglyphs, have
been discovered in the park. In the 16th century, Spanish
explorers visited the area, and by the mid-19th century a U.S.
team had surveyed an east–west route through the park and noted
the petrified wood. Later roads and a railway followed similar
routes and gave rise to tourism and, before the park was
protected, to private removal of the park's fossils. Theft of
petrified wood remains a problem in the 21st century.
