Petrified+Forest

= **__Petrified Forest__** = By: Adam Walsh and Sam Harada

Introduction
Petrified Forest National Park, established in 1962, is located in northwest Arizona, near Holbrook. 5 It covers 342 square miles of land in total. Its large quantity of petrified (transformed into stone) wood makes it unique among the U.S. national parks; such a concentration is difficult to find anywhere else in the world.

Wood Petrification
These logs were transported through large river system that had forests upstream. When a 'log jam' occurred, the logs were stopped and then buried under sediment and minerals. This allowed for petrification of the wood. Wood becomes petrified when its structure and cell walls have been replaced with silica. For this to occur, the wood must be buried where no oxygen can reach it, preventing decay. Silica solutions enter the wood and crystals are left on the cell walls. Often, petrified wood is vibrantly colored; substances such as iron oxide can stain it. 2

Highlights

 * The Agate Bridge, formed by the ground eroding under a petrified log. 1
 * The Agate House, a building made almost entirely of petrified wood. It was created by the Pueblo. 1

Images

 * [[image:800px-PetrifiedWood.jpg width="320" height="240" caption="A section of a petrified log. The colors are due to mineral staining.   5"]] || [[image:onyxbridge.jpg width="305" height="235" caption="The Agate Bridge.       5"]] ||
 * [[image:http://upload.wikimedia.org/wikipedia/commons/7/7d/Petrified_Forest_National_Park_AZ.jpg width="321" height="245" caption="The landscape of the park.           5"]] || [[image:http://www.nps.gov/pefo/historyculture/images/AgateHouse_285px.jpg width="319" height="242" caption="The Agate House.        1,9"]] ||

At one time, the park contained an extensive stream system. The streams both deposited and eroded sediment, forming such features as the Agate Bridge and transporting the logs that would eventually become petrified. The dry channels remained.

Biome
The park, along with most of the rest of Arizona, is a desert biome. Plant life is sparse (though not nonexistent) and the soil is exceedingly dry.



Human Impact
The region was inhabited by Native Americans and later 'discovered' by Spanish explorers and then the U.S. army. American entrepreneurs started breaking up petrified wood formations to look for valuable gems inside. By 1962 3, this caused the government to designate the area a protected area to preserve the wood.

Additionally, theft of petrified wood from the park by visitors is ongoing. The government has allowed the sale of wood from outside the park in an effort to reduce theft.