Two petrified forests should be on every gem, mineral and fossil lover’s visit wish-list: the Petrified Forest at the Black Hills of South Dakota and the Petrified Forest National Park in northeastern Arizona. Over 1,100 miles separate the two parks, but the conditions that turned the ancient trees into petrified wood are similar. Ancient petrified forests are the perfect attraction for exploration, discovery, and education about petrification – the geological process during which organic material becomes a fossil.
Petrified Forest in South Dakota
The Petrified Forest of South Dakota is located at the scenic Black Hills near Rapid City, and rests on the Elk Creek Lodge Resort land. The lodge, cabins, Petrified Forest, museum, rock shop, camping ground and hiking trails occupy 150 acres of land. The Petrified Forest opened to the public in 1929 and is one of the largest outcroppings of fossilized wood in that area.
Evergreen trees cover the Blacks Hills of western South Dakota and from a distance the hills appear dark, hence the name “Black Hills”. They are considered a sacred site for the Native American Lakota people. The Black Hills were also the site for the 1875-1878 gold rush, when thousands of miners invaded the area forcing the government to break the previous treaties with the Native Americans.
At the time of the dinosaurs during the Cretaceous Period, the mountain range of the Blacks Hills we know today was a tropical swamp. The cypress trees were submerged into water, and over time, sand and silt permeated the wood and turned them into stone. Originally the logs were buried deep under the sediments but as the Black Hills formed, the former swamp rose and the petrified logs broke apart. Eventually the sand layers wore away and the Petrified Forest was uncovered. The ancient petrified trees lay exactly where they fell 120 million years ago.
Petrified Forest Tour & Museum
The Elk Creek Resort Petrified Forest offers a one-hour guided tour. The tour starts at the museum with a 15-minute video, which shares the history of the Black Hills and explains how the forest trees become fossilized or petrified. The tour continues through the museum, and then visitors can walk outside a mile loop to the Petrified Forest.
The museum houses an outstanding collection of cut and polished petrified wood specimens, local rocks and minerals, more than 3000 Native American artifacts, and a wealth of South Dakota fossils. Their Gallery of Stone rock shop specializes in petrified wood from the Black Hills, but also rocks and minerals from other areas.
The Petrified Forest is located at 8228 Elk Creek Road, Piedmont, South Dakota, Tel. 605-787-4560, www.thepetrifiedforest.net .They are open daily, April to November weather permitting.
Petrified Forest National Park in Arizona
The Petrified Forest National Park is famous for its fossils, especially fallen trees that lived in the Late Triassic Epoch about 225 million years ago. There are also badlands, buttes and mesas, ancient petroglyphs, museums, and vast vistas for all to enjoy. Visitors can drive around, stop at the overlooks, or hike the trails.
The Petrified Forest was first declared a National Monument in 1906 and a National Park in 1962. The park covers about 346 square miles in Navajo and Apache counties. It is located immediately outside the southern border of the Navajo Reservation, nineteen miles east of Holbrook. The park stretches 28 miles north to south, with two entrances, one in the north off I-40 at Exit 311, and the second in the south off Hwy 180.
Museums & Walking Trails
Near the park’s south entrance is the Rainbow Forest Museum with displays of many beautiful polished petrified wood and quartz specimens, dioramas and education charts explaining the formation of the petrified forests.
Visitors can walk several trails through the park. The Giant Logs Trails Loop is 0.4 mile in length and features some of the largest and most colorful logs in the park. “Old Faithful”, at the top of the trail, is almost ten feet wide at the base. The Long Logs Trail Loop is 1.6 miles in length and features the largest concentrations of petrified wood in the park.
A famous landmark within the park is the Agate Bridge, a 110-foot fossilized tree. Contrary to the current National Park Service philosophy of letting natural forces run the course, in 1911, masonry pillars were erected beneath the log, and in 1917, they were replaced by concrete.
The Petrified Wood Formation
During the Late Triassic, downed trees accumulating in river channels were buried periodically by sediment containing volcanic ash. Groundwater dissolved the silica (silicon dioxide) from the ash and carried it into the logs, where it formed quartz crystals that gradually replaced the organic matter. Traces of iron oxide and other substances combined with the silica to create varied colors in the petrified wood.
Much of the park’s petrified wood is from Araucarioxylon arizonicum, an extinct conifer tree. Most logs retained their original external form during petrification. At least nine species of extinct fossil trees from the park have been identified. Whole petrified trees fractured into segments lay on the ground reminiscent of fallen ancient Greek columns. It is a breathtaking site to see where hundreds if not thousands of logs are spread all over the ground.
It is strictly forbidden to pick up any petrified wood at the National Park. You can satisfy your needs at the nearby Painted Desert Indian Center, where petrified wood from land outside the park is sold by the pound or by specimen.
Newspaper Rock Petroglyphs
One of the largest concentrations of petroglyphs with over 650 images that adorn boulders is known as Newspaper Rock, located within the Petrified Forest National Park. The petroglyphs were created by people who farmed the Puerco River Valley 650 to 2000 years ago. They are carved through a patina called ‘desert varnish’ which forms on the rocks’ surface, a veneer of iron and manganese oxides, clay minerals, and organic material, revealing the lighter colored rock beneath. Visitors can also stop by the nearby Puerco Pueblo ruins.
The Petrified Forest National Park is open year round. For information visit www.nps.gov/pefo/index.htm
