Over time, trees dried or were knocked down by flood waters or wind. Rivers carried the trees into the lowlands, breaking off branches, bark, and small roots along the way. Some trees were deposited on the flood plains, while others were buried in the stream channels. Of these, some were petrified, creating the fossilized logs of today.
Before some logs decayed, volcanic ash was deposited in the sediment. Ground water dissolved silica from the ash. The solution crystallized as mineral quartz in the walls of the logs. Minerals containing iron combined with the quartz, creating colour in the fossilized logs.
Over further time, uplifting of the land’s surface exposed the fossilized logs, strewing them about. They are brittle and easily broken. As more erosion caused by wind and water occurs, more logs are exposed.
In Petrified Foest National Park in the US State of Arizona, the fragments are considered by some visitors as a souvenir source, even though it is illegal to remove anything found in the park. It is reported that more than one ton of petrified wood is removed each month by them. Should this not be a concern to visitors?
Return to Petrified Forest National Park, in the Parks section of this website.
(This page was updated in November 2012.)