Petrified Forest National
Located in northeastern
Petrified Forest National Park is located between
Arizona, along I-40 and old
Route 66. The park is a surprising land of scenic
wonders and fascinating science featuring one of the world's largest and
most colorful concentrations of petrified wood, the multi-hued badlands of
the Chinle Formation known as the Painted Desert, historic structures,
archeological sites, and displays of 225 million year old fossils.
The park consists of two large areas connected
by a north-south corridor. The northern area encompasses part of the
multihued badlands known as the Painted Desert.
The southern area includes colorful terrain as well as several
concentrations of petrified wood. Several American
Indian petroglyph sites are also found in the southern
The natural world of Petrified Forest is far
more complex than it seems on the surface. Located near the southern edge
of the Colorado Plateau, the park is part of an amazing geological region
which also includes other famous geological parks such as the Grand
Canyon, also in
Bryce, and Arches National Parks in
Utah. Each has its own character, including which layer of the geological
story is featured by that park.
More than 200 million years ago, large trees
and rich vegetation flourished in northeast
that time, the region was a tropical wetland with abundant streams
and rivers. During heavy rains, the waterways would flood, sweeping fallen
trees into the sandy floodplains. Later, volcanic lava destroyed the
forest, and the remains were embedded into sediment comprised of volcanic
ash, mud, and water. Trees are transitioned to stone by the process of
permineralization, a process of fossilization in which the organic
materials are replaced with minerals, such as quartz, making a "cast" of
the original organism. Millions of years later, the petrified logs were
revealed by erosion.
Much of the striking
banded coloration of the Chinle Formation badlands that make up the
Painted Desert region is due to soil formation during the Late Triassic
period. The soil suggests that the climate was once dramatically seasonal,
with distinct very wet and very dry seasons. This climate was probably
similar to the modern monsoon of the Indian Ocean region.
The colorful mudstones and clays of the Painted Desert badlands are
composed of bentonite, a product of altered volcanic ash. The clay
minerals in the bentonite absorb water, and the expansion and contraction
properties of the bentonite cause rapid erosion. This prevents vegetation
from growing on the slopes of the hills.
Other prominent features created by erosion are the plentiful mesas and
buttes located throughout the park. Both have flat tops of more
erosion-resistant sandstone over softer clays. Mesas are quite broad but
not very tall, while buttes are taller and more narrow.
The Petrified Forest and
are also rich in human history, which dates back more than 13,000 years.
More than 600 archeological sites have been found in the park. Folsom-type
spear points, the earliest artifacts of Paleo-Indians, which lived during
the final glacial episodes, have been found, as well as many more
artifacts, petroglyphs, and the remains of pueblos from later inhabitants.
People of the
Painted Desert & Petrified Forest
From the 16th through the 18th centuries, explorers looking for routes
between Spanish colonies along the Rio Grande to the southeast and other
Spanish colonies on the Pacific coast to the west passed near or through
the area, which they called El Desierto Pintado, the Painted Desert.
However, the park's oldest Spanish inscriptions, left by descendants
of the region's early Spanish colonists, date only to the late 19th
The Petrified Forest area was designated a National Monument on
December 8, 1906. The Painted Desert was added later, and on December
9, 1962, the whole monument received
National Park status. Today, the
park covers 93,532.57 acres.
Desert Inn was built in 1924
on a high perch overlooking the Painted Desert
by a man named Herbert Lore in 1924. The two-story inn, nicknamed
named the Stone Tree House, due to the petrified wood used in its
construction, was operated as an inn and tourist attraction.
This isolated oasis was purchased
Petrified Forest National Monument in 1936 and began updating the
structure. It would later become the headquarters of the park and
service thousands of
travelers. It closed in 1963 and sat vacant and deteriorating for
years. Today, it is fully restored and serves as a museum. (see full
history of the
Painted Desert Inn on Page 2).
The petrified wood of the
Petrified Forest is the "State Fossil" of
The pieces of permineralized wood are from a family of trees that is
extinct in the Northern Hemisphere today, surviving only in isolated
stands in the Southern Hemisphere.
During the Late Triassic period, this
desert region was located in the tropics and was seasonally wet and dry.
In seasonal flooding, the trees washed from where they grew and
accumulated in sandy river channels, where they were buried periodically
by layers of gravelly sand, rich in volcanic ash from volcanoes further to
the west. The volcanic ash was the source of the silica that helped to permineralize the buried logs, replacing wood with silica, colored with
oxides of iron and manganese.
Landmarks in the park include the
Agate House Pueblo, built of petrified wood; the
Agate Bridge, a
petrified log spanning a wash, the
Painted Desert Inn,
designated on the National Register of Historic places, an old segment of
Route 66, and the
Puerco Pueblo, as well as numerous scenic formations and
Some 225 million years ago, numerous tall trees washed into the
floodplain, where a mix of silt, mud and volcanic ashes buried the logs.
The sediment cut off oxygen and slowed the logs decay. Silica-laden
groundwater seeped through the logs and replaced the original wood tissues
with silica deposits.
Eventually the silica crystallized into quartz, and the logs were
preserved as petrified wood. Later, centuries of scouring floodwaters
washed out the arroyo beneath this 110-foot long petrified log and formed
a natural bridge. The petrified log, harder than the sandstone around it,
resisted erosion and remained suspended as the softer rock beneath it
Enthusiastic visitors, fascinated by the bridge worked to preserve it
through the establishment of Petrified Forest National Monument in 1906.
Conservationists felt this ages-old natural bridge needed architectural
support and in 1911 erected masonry pillars beneath the log. In 1917 the
present concrete span replaced the masonry work.
Current National Park Service philosophy allows the natural forces that
create unusual features to continue. If discovered today, Agate Bridge
would be left in its natural state.
Agate Bridge before architectural support was added, photo 1895.
Agate Bridge in 1911 after masonry pillars were placed beneath it.
This image available for photo prints & commercial downloads
The ancestors of the modern Pueblo people used petrified wood for a
variety of purposes including tools such as projectile points, knives, and
scrapers. Agate House demonstrates another innovative use of petrified
wood, as a building material for masonry structures. The ancestral Pueblo
inhabitants constructed this small, eight-room pueblo about 900 years ago
in a location near to both agricultural fields and petrified wood
deposits. The size of the structure and time necessary to build and
maintain it indicates that this was not a temporary residence or field
house, but, more likely a year-round residential structure for a family
unit. Others have suggested that this structure served solely ceremonial
purposes and did not serve as the residence for a family group. Like most
structures from this time period it likely remained in use for less than a
generation or thirty years.
It is estimated that Agate House was constructed and occupied between 900
and 1200 AD. This determination is based on the ceramic assemblage
discovered at the time of excavation, including coiled utility ware and
various black-on-white painted ceramics with a few examples of
black-on-red. Most of the pottery appears to be associated with ancestral
Puebloan people (Anasazi), although some of the pottery has southern
origins, perhaps associated with the Mogollon.
According to the 1933-34 site excavation report, Agate House was
constructed using medium to large pieces of petrified wood, which were
presumably carried to the top of the knoll. The walls were originally
constructed of petrified wood held in place by mud mortar and chinked with
smaller pieces of petrified wood. The eight room
pueblo is thought to have been
occupied for a brief time due to the small amount of cultural debris
found in the area. Reconstruction of its rooms occurred after
archaeological excavation in 1934.
The Agate House is located on top of a small hill within the Rainbow
Forest. Some questions remain about the accuracy of this reconstruction,
but, it still enables us to envision the daily lives of the ancestral
Agate House was listed on the National Register of Historic Places in 1975.
To get to the Agate House, there is a two mile round trip trail from the
Rainbow Forest Museum parking area. The first half-mile of this trail is
paved and suitable for strollers and various mobility equipment (power and
manual). The rest of the trail may be negotiated out to Agate House, but,
it is narrow width and very rough surface, not suitable for some
wheelchairs and other equipment. Upon reaching the Agate House, leave all
archeological artifacts for all to enjoy. Also note, this dwelling is
fragile. Do not sit, stand, or lean on the walls.
Continued Next Page
From Legends' General Store
66 Books -
Legends of America and
Rocky Mountain General Store has collected a number of
Route 66 Books for our
enthusiasts. As great as
Route 66 is, if you aren't armed with a few good
tools on your journey, you'll miss great attractions, eateries, places to
stay, and wind up on the wrong path. To see this varied collection that
includes "how-to" books, travel guides, photograph books, attractions, and