Crystal Forest Trail, Petrified Forest National Park

The Triassic-era conifers that comprise most of the fossilized logs in Petrified Forest National Park were buried by stream-deposited sediment, including volcanic ash, then gradually turned to stone by the slow replacement of organic matter by silica, to form quartz. For most of the logs in the park, the mineral is massive, lacking obvious crystalline faces, but in one section the fossils contain cavities in which actual crystals were found, a mix of clear quartz and purple amethyst - a region that became known as the Crystal Forest.

Although all the best specimens were removed long ago by souvenir hunters, some of whom even blew up large logs using dynamite to extract the crystalline inclusions, a few small examples remain, while the area also has many more conventional logs, typically large, varied in form, and beautifully coloured.

The Crystal Forest may be viewed along an easy, paved, three quarters of a mile loop trail, one of the most popular paths in the park, across flat terrain of small mounds and little gullies, with the fossils strewn all around. All the bedrock hereabouts is from the Blue Mesa Member of the Chinle Formation, a mix of sandstone and mudstone.