The Arizona petrified forest is probably the best known in the world due to its vibrantly colored “rainbow wood” and the Petrified Forest National Park. This petrified forest extends over a huge area, around 100k acres, but only a small portion is located within the national park. The fossilized wood found in the Chinle Formation is Late Triassic in age, or approximately 225 million years old. The dominant tree species in the forest is Araucarioxylon arizonicum, a type of conifer related to the living “Monkey Puzzle Tree”.
What Gives Arizona Petrified Wood Its Vibrant Coloration?
Often referred to as rainbow wood, much of the petrified wood from Arizona comes in very vibrant red, orange, yellow and purple hues. The reds, oranges and yellows are produced by various, large particulate forms of iron oxide. The yellow being from limonite inclusions and the red/oranges being from hematite.. Rarer purple and blues are produced by manganese dioxide. This is a secondary material formed when water leaches manganese from igneous rock and re-deposits it as a concentration of manganese dioxide.
How Was The Petrified Wood Formed?
The forest originally formed in the Upper Triassic, about 225 million years ago in the Northwest area of the supercontinent Pangaea. The area had a tropical climate and a vast forest grew upon a relatively flat-lying terrain. Downed trees that accumulated in river floodplains and channels were periodically buried by floods carrying fine, volcanic ash.
Because of the rapid burial and lack of oxygen the wood did not decay as it would if it was on the surface. Minerals, including silica dissolved from volcanic ash, absorbed into the porous wood over hundreds and thousands of years. It crystallized within the cellular structure, replacing the organic material. Other minerals such as iron oxides also were deposited along with the silica providing the color. These petrified logs became buried under thousands of sediment over time but uplift and erosion eventually re-exposed them at the surface where they are found today.
What Species Of Wood Are Found In The Arizona Petrified Forest?
Araucarioxylon arizonicum - 95%+ of the fossilized wood found in the Arizona petrified forest is from Araucarioxylon arizonicum a type of conifer that could grow up to 200 feet tall. It is the state fossil of Arizona and is related to the monkey puzzle tree living today. All of the rainbow wood is of this species.
Woodworthia arizonica - The second most common species in the petrified forest. It is characterized by circular small scars on the outer surface of the tree rounds. In cross-section view these scars usually appear as white veins radiating outward from the central core of the tree. It grew to about 100 feet tall.
Schilderia adamanica - One of the rarer woods in the petrified forest. Its classification in relation to other members of the plant Kingdom is uncertain. In cross-sectional view, it is recognized by its numerous thin veins radiating outward from the central core. It grew up to about 120 feet tall.
At least nine species of fossil trees from the park have been identified, all extinct as well as other plants including lycopods, ferns, cycads and ginkgoes.
Does Your Petrified Wood Come From The Petrified Wood National Park?
No, it is illegal to collect or remove petrified wood from within the National Park. The entire forest expends over nearly 100k acres with only about 5% being located within the park. The petrified wood we carry is collected from private ranches in the area of Holdbrook, Arizona.
Washington state has now joined over a dozen other states to put in place “shelter in place” or “stay at home” orders. While we agree this is the correct course of action, it will have a substantial impact on our business. It effectively shuts down much of our company for several weeks.
We will continue taking orders on our website and we will have a single staff member at our warehouse to facilitate shipping of these new orders. Depending on the order volume this may mean that we do experience some shipping delays, particularly with large or fragile items that require more packaging time.
These shutdowns are particularly devastating to all small businesses who don’t have significant cash reserves and rely on constant cash flow to pay their fixed expenses (payroll, rent, loan payments, etc) We hope that you will continue to support us and satisfy your fossil fix during these trying times.