Petrified Wood
Petrified Forest National Park is a United States national park in
Navajo and Apache counties in northeastern Arizona. Named for its large
deposits of petrified wood, the fee area of the park covers about 170
square miles (440 square kilometers), encompassing semi-desert shrub
steppe as well as highly eroded and colorful badlands. The park's
headquarters is about 26 miles (42 km) east of Holbrook along Interstate
40 (I-40), which parallels the BNSF Railway's Southern Transcon, the
Puerco River, and historic U.S. Route 66, all crossing the park roughly
east–west. 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 800,000 people visit the park each year and take part in
activities including sightseeing, photography, hiking, and backpacking.
Averaging about 5,400 feet
(1,600 m) in elevation, the park has a dry windy climate with
temperatures that vary from summer highs of about 100 °F (38 °C) 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 Period, 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 area where the park is now located 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
large-scale removal of fossils. Theft of petrified wood remains a
problem in the 21st century.
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