Desert Messenger

16 www.DesertMessenger.com January 7, 2015 SEE PETRIFIED WOOD PAGE 18 Looking out over the vast expanse of desert covering much of Arizona, it is diffi cult to imagine a landscape cov- ered with dense tropical forest. But in reality, from 250 million years ago to about 5 million years ago, the desert southwest was tropical, full of trees and volcanoes; and it was because of that tropical, forested environment that Arizona has its state fossil. Pet- rifi ed wood was designated the state fossil of Arizona in 1988. Petrifi ed wood is wood that has been changed to stone through processes known as permineralization and replacement. By Jenn Jedidiah Free for RocksInMyHead™ The fine art of petrification Two specifi c conditions must exist in order for a fallen tree to turn into petri- fi ed wood. First, the fallen tree or limb must get buried in an environment de- void of oxygen, like mud or heavy sedi- ments. In an anaerobic environment, the organic matter will not decompose. The second condition is that there must be mineral-rich water fl owing through the sediments and the wood. Permin- eralization occurs as minerals fl ow into the original tissues of the wood and replace the organic matter molecule by molecule. Empty spaces in cells are fi lled with crystals. The original shape and structure of the wood is retained, though all organic matter has been re- placed by minerals. This process can take anywhere from hundreds to thou- sands to millions of years, depending on environmental factors. Petrifi ed wood is found throughout the world. Here in Quartzsite, Petri- fi ed Wood can be found locally along the Colorado River and Martinez Lake. Another site nearby is Alamo Lake, where gorgeous specimens of Petrifi ed Palm Wood can be found. The most well-known, largest, and by far the most beautiful Petrifi ed Wood found in Arizona is in the area in Eastern Arizona located near Petrifi ed Forest National Park. Referred to as "Rain- bow", the famous specimens from this area near Holbrook and Winslow are clearly some of the most beautiful pet- rifi ed wood in the world. The color of petrifi ed wood depends on what minerals are present when it is forming. Typically it is some form of quartz or chalcedony with various oth- er minerals found in trace amounts. In the Holbrook area, a silica solution produces specimens with varieties of quartz such as agate, jasper, and some- times opal, or even pockets of clear quartz crystals or purple amethyst. The colors in petrifi ed wood are the result of the trace minerals in the solu- tion. Copper, cobalt, or chromium pro- duce a green or blue color for example. Iron oxides create reds, browns, and yellows. Manganese produces pink and orange, while blackish/yellow and First locally-owned and operated music station in Quartzsite, Arizona. Proudly serving the communities of Quartzsite, Bouse, Brenda, Rainbow Acres, La Paz Valley and beyond, since 1988. Quartzsite Radio • Quartzsite's Favorite "CLASSIC HITS" • Local Information • Weather • 24 Hours Day / 7 Days Week! KBUX 94.3 FM 928-927-5111 http://kbuxradio.com ADVENTURES WITH ROCKS sometimes green comes from manga- nese oxides. Black is the result of an abundance of carbon, brown and grey is produced by magnesium, and white is created by an excess of silica. The geology of the Holbrook area is rich and varied. The deposits left from ancient rivers and sea beds created the Chinle formation, which consists of colorful Badlands, fl at-topped me- sas, and sculptured buttes. Within the Chinle formation are layers of volcanic tuff, mudstone, and sandstone. The sandstone layer consists of reddish mudstone and brown sandstone, and it is this layer that contains the large amounts of beautifully colored petri- fi ed wood known throughout the world as "Rainbow". The petrifi ed wood found in this layer has been dated to the Jurassic Period around 213 million years old, give or take a couple million years, and has been identifi ed as gink- go and conifer. Other fossils found in this area are of giant reptiles and am- phibians, such as Postosuchus, a huge pre-historic crocodile. The petrifi ed Ironwood of the Colo- rado River Basin is found in the basal carbonate of the Bouse Formation, a volcanic layer of basalt containing high amounts of atmospheric carbon diox- ide. The fl ood basalts of the Colorado River Basin are lava fl ows from the

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