Petrified WoodPetrification is the process by which organic material is converted into stone by impregnation with silica. It is a rare form of fossilization. Petrified wood is the most well known result of this process, but all organisms from bacteria to vertebrates can be petrified. Petrified wood can be found in every US state and in many countries around the world. During the late Triassic Period, much of Northern Arizona was a heavily wooded tropical floodplain. Period flooding and erosion interspersed with volcanic activity from the south and west carried sediments and ash downstream, settling over fallen trees in this area. In some cases trees were buried quickly and deeply enough to deprive them of oxygen, thus significantly slowing the natural decomposition process. Over time, ground water dissolved silica from volcanic ash into the porous body of fallen, buried trees. This solution formed quartz crystals that filled hollows and cracks in the logs, eventually petrifying them by encasing and fully replacing the trees' organic material with minerals. The wood's brilliant colors come from impurities in the quartz, such as iron, carbon, and manganese.