Petrified wood is a type of fossil formed when the organic material in wood is replaced by inorganic materials, such as minerals. It is commonly found in regions with volcanic activity, mudslides or other land displacement in which wood may be buried.
When wood is buried under sediment deposits, it prevents decomposition from exposure to oxygen and other elements. This allows the wood to be preserved for the necessary time needed to become fossilized. Petrification occurs when minerals are dissolved into water and contact wood buried underground. The mineral solution may then replace portions of the wood and harden into mineral structures, preserving and fossilizing any organic material that remains.