"Visitor Centers" Top 5 Page for this destination Petrified Forest National Park Things to Do Tip by BruceDunning

The visitor center at the south has a 20 minute film of the Triassic period when these logs were mostly formed. They fell into water and this was a jungle setting millions of years ago. When saturated, they fell to the water bottoms. Later silt covered the logs and that deprived it of oxygen. That then led to a chemical change where silicate (quartz) leeched into the wood and replaces the wood cellulose fibers. Minerals like copper, iron, and magnesium also leech into the wood but the tree structure remains intact. These minerals solidify and later harden, which creates the solid mass and the color. When ground upheavals later occurred, some of these logs popped up to the surface, and here they are today. A detail explanation is in the attached to better explain the process better than me.
While I was there only the Rainbow VC had the film available,; maybe that changes in the future where both VC have the film which is quite nice to see. The visitor centers are Rainbow at the south, and Painted Desert at the north, and Painted Desert Inn as an historic site. Rainbow has the museum and exhibits, while the Painted Desert is mostly gift shop and Fred Harvey restaurant.

Website: http://en.wikipedia.org/wiki/Petrified_wood