User:FossilDS/sandbox2

The fossil wood of the Mississippi Petrified Forest are part of the Forest Hill Formation,^[1] a formation of fine sand and clay, deposited by an ancient river 33 million years ago, during the early Oligocene.^[2] The future site of the Mississippi Petrified Forest in the Oligocene was a floodplain, exposed by the retreat of global sea levels at the end of the Eocene where trees, such as firs, maples, and the extinct cypress Cupressinoxylon grew in an riparian environment.^[3] The species makeup of the forest suggests that the climate was cooler than modern Mississippi.^[2] The numerous trees of the petrified forest were thought to have been buried as part of a log jam, due to the lack of stumps and the lack of smaller limbs on fossil logs,^[2] and were buried by the meandering action of ancient rivers.^[3]

The trees underwent petrifaction relatively close to the surface, in the weathering zone of the Forest Hill formation. Sulfide minerals associated with lignite chemically weather, creating a hyper-acidic environment around the fossil wood, which allows silica in the surrounding sand to replace cell walls with minerals such as chalcedony and quartz.^[4] The now silicfied trees were exposed when the loess overlaying the fossiliferous layers erode away, creating a badlands terrain where fossil logs are exposed in the walls of gullies and cliffs.^[3]

The site features a museum with examples of petrified wood found in every state and from other countries. The samples include a variety of plant materials, including leaves, fruits, cones and bark. Other fossils and fossil casts are on display, including dinosaur footprints, whale bones and turtle shells.