Petrified Conifer, Arizona wood disc, Araucaria

A polished wood slice of petrified conifer wood from Arizona, from the Triassic genus Araucaria. A cross-section through a tree trunk from a forest that lived 220 million years ago.

Petrified wood from the Petrified Forest National Park is about 220 million years old. The trunks of the Araucaria genus lay in volcanic ash. Silicic groundwater penetrated the wood, replacing the organic material cell by cell with quartz, chalcedony, or opal.

The red-brown color bands are caused by embedded iron oxides. Each ring documents a year of growth during the Triassic period, a paleontological teaching board in stone.

The deposit is one of the oldest and richest in the world. Today, retrieval in the park area is prohibited. Well-preserved material comes from historical collections or neighboring private lands.

A paleontological collector's item with museum presence and 220 million years of Earth's history.