Petrified Forest

Located in Arizona, Petrified Forest National Park is known for its large deposits of fossils, notably petrified wood. These trees lived about 225 million years ago, during the late Triassic Period. First named a national monument in 1908, the area became a national park in 1962. Petrified wood is a specific type of fossil in which a tree or treelike plant has completely transformed into stone by a process in which minerals replace the organic materials. Streams deposited fallen conifer trees, which were buried so quickly in the sediment along with the remains of plants and animals also in the water that they did not decay. As the stream ran over the trees, silica from volcanic ash in the sediment transformed into quartz crytals and replaced the organic matter in the logs. Iron oxide, manganese oxide, quartz, and other minerals created the colors we see today; the brown colors seen here indicate the presence of iron oxide.