Mississippi "Petrified Wood" !

After considerable discussion about minerals, rocks and gems, the Mississippi State Legislature recognized Petrified Wood as the state stone on May 14, 1976.

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Petrified Wood in Mississippi comes in several varieties: a nondescript type called "silicified wood," a denser type called "massive silicified wood," and a third type known as "petrified palm wood." Because it is difficult to know exactly which trees these woods came from, they are assigned to paleobotanical form genera with the suffix -oxylon (meaning "looks like") -- hence wood which resembles that of modern palms is called Palmoxylon, but may or may not be from trees closely related to modern palms. Most of the best petrified wood from Mississippi comes from trees which grew in the state during the Oligocene Epoch, around 30 million years ago. The Gulf of Mexico's shoreline extended further north at that time, which explains why the wood is found in the more northern parts of the state. The only one of its kind in the eastern half of the United States, the Mississippi Petrified Forest is a privately-owned Registered National Landmark featuring 35-million-year-old fossilized logs. Once part of a massive primeval forest, the trees were uprooted by a large flood that eventually turned the wood into stone at the bottom of the river. Most of the logs are now between five and 10 feet long, but they were over 100 feet high and perhaps 1000 years old.

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Washington's "Petrified Wood" !

Because of the abundance and popularity of this item, the Washington State Legislature designated Petrified Wood as the state gemstone in 1975 (though rock-hard and beautiful, petrified wood is not actually a gem but a fossil).

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The most popular and abundant fossil to garner state honors is Petrified Wood. Most of the petrified wood in Washington grew during the Miocene Epoch, some 5 -12 million years ago, when the state was swampy and mild, and played host to vast forests of cypress, oak, elm, and ginkgo trees. Petrified wood forms when logs are buried, and their organic matter is replaced by minerals in the groundwater, primarily silica. Although much petrified wood is buried in river sediments and is thus found in mudstone or sandstone, the trees in ancient Washington grew next to large volcanoes which spewed tons of ash into the air when they erupted. This volcanic ash settled and buried the trees in place; sometimes they were even engulfed by lava flows. The major petrified wood-bearing unit in Washington is the Columbia Plateau basalts. The most famous petrified wood site in the state is Ginkgo Petrified Forest State Park near Vantage. Many types of wood are preserved there, but the abundance of Ginkgo wood gave the park its name. Ginkgos are gymnosperm trees (non-flowering plants in the same grouping as pines, spruces).

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Although Petrified Wood occurs in the western portion of the state, it is rarer than in the east. The western portion of North America is a newcomer by geological standards, consisting of a mèlange of terranes which have been splatted up against the ancient core of the continent by plate tectonic action. Thus the eastern portion of the state has been dry land for a longer period of time, and has had more time than coastal regions to develop forests and fossils.

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Petrified wood of different varieties are also the state stone of Texas, and the state fossil of North Dakota and Louisiana.

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