Petrified forest

Petrified forest, stone-covered trunks of coniferous trees. The trunks were buried in mud, sand, or volcanic ash and mixed with running water, which carried dissolved minerals. The result is stone that shows the detail of the original wood. Many logs are rainbow colored as a result of oxidation. The most famous such forest is in Petrified Forest National Park in eastern Arizona.

See also: Fossil.