Petrified Forest

Visitor Center in the background

Trees do not "turn to stone" in the literal sense of the word. Many years ago a forest grew here. It was covered by ashes and mud from an active volcano. Water seeped down through this dust, carrying volcanic ash. Gradually the wood was replaced by the silica, in many cases cell for cell. So perfectly was this accomplished that very thin sections of the petrified wood can be studied microscopically and their structure determined. This process of petrification took a long time and gradually the mud and ash deposited ages ago were eroded away.

...at your feet is volcanic ash composed of sparkling glass shards and fine particles of volcanic dust. Silica is present in molecular form which is carried down by water through the ash toward the buried forest. Orange streaks and clusters present are concretions of iron.

These coastal redwoods fell like matchsticks in the direction of flow from a volcanic explosion.
The source of the blast came from behind the present-day Mt. St. Helena, seven miles to the northeast.
A blanket of volcanic ash covered these trees for several million years. The ground during this time became saturated with water containing dissolved silicon and oxygen or silica from the overlying ash.
The molecules of silica replaced the molecules of wood, turning wood to solid silica, quartz and stone. - From a trailside informational sign

Exposed length - 105 feet
Diameter - 6 feet
Species - California Coastal Redwood
Discovered - 1919