Gila Ben

Petrified wood became the official state fossil of Arizona in 1988. Most of the petrified wood in Arizona can be found in the Petrified Forest National Park in the northeastern part of the state. Millions of years ago, much of the area was covered by swamps. When trees fell, they became buried under layers of mud. Slowly the living material of the tree was replaced with minerals, leaving a brightly-colored rock replica of the plant.

On December 8, 1906 President Teddy Roosevelt signed a proclamation establishing the Petrified Forest National Monument. In 1962 Congress passed a bill elevating the monument into a national park.