As new as the Chinle Formation is, there is an even younger layer that can be seen in places. After the Chinle sediments were put down, a layer of lava from long gone, but formerly local volcanoes, created another layer called the Bidahochi Formation. It is aprox. 12 million years old and can be seen at Pilot Rock in the Painted Desert and a few other places. It is basically basalt.
You will occasionally see a butte in the park. How are they formed? It was a question that interested me. A butte is basically harder rock than that which is around it. The softer stone erodes away leaving the spire. Also some of them are old lava tubes from volcanoes. (This is essentially how the petrified logs were exposed again after such a long period of time. They are very hard rock surrounded by essentially sandstone which is very soft!) The rubble deposits of the actual volcanic cone have completely eroded away leaving the lava filled tube standing by itself. I didn't know this, but there are over 200 existing volcanic cones in northern Arizona and one, Sunset Crater, erupted only 1000 years ago. The area is considered to still be active.
Results 1-3of 3 Reviews
June 26, 2006
From journal Driving Across the USA
St. Louis, Missouri
August 30, 2003
From journal Petrified Forest-Shadows of a Long Time Past!
by Amy Travels
Bethel Park, Pennsylvania
December 30, 2000
Since we were approaching the park from Holbrook, which is to the west, we entered at the south entrance, off of Highway 180. If you are entering the park this way, I recommend fueling up in Holbrook, since Highway 180 is pretty desolate.
We stopped at the Rainbow Forest Museum and Visitor Center upon entering the park. This gave us a good background on how the petrified wood came about. Giant Logs Trail is located behind the museum/visitor center. This easy trail takes you through one of the highest concentrations of petrified wood in the park. I recommend this trail.
Other points of interest in the park are Agate Bridge, the Badlands area, the Tepees. You can also find petroglyphs at Newspaper Rock and Puerco Pueblo areas of the park.
On the northeastern end of the park (near I-40 entrance) are the Painted Desert overlooks. While there were at least five overlooks, we only stopped at two because it looked pretty much the same from both. The Painted Desert Visitor Center is located in this area of the park.
The entrance fee for the park is $10 per private vehicle. This is good for seven days. Or, if you have the National Park pass, admission is included. Removing petrified wood from the park is illegal. While at the Rainbow Forest Museum, we enjoyed reading letters from visitors who experienced lots of bad luck after removing petrified wood from the park. Instead, purhase petrified wood at the gift shop located across from the Rainbow Forest Museum. This petrified wood was removed from private land.
From journal Driving through Arizona