Mount St. Helena buried an entire redwood forest alive and you can walk through it today

Petrified Forest of Calistoga

The Petrified Forest of Calistoga showcases massive ancient trees turned to stone. A violent volcanic eruption 3.4 million years ago buried these giants, preserving redwoods that once stood 8 feet wide and 120 feet tall.

The site ranks among the world’s best examples of a preserved ancient forest. Visitors today can walk among these stone giants and touch trees that grew when mastodons and early camels roamed California.

Mount St. Helena’s Explosive Origin

Mount St. Helena stands 7 miles from the petrified forest. This now-quiet mountain was once an active volcano with a violent past. The Wappo people named it “Kanamota” or “Human Mountain.”

Spanish settlers later renamed it Mount Mayacamas before Russians gave it its current name in 1841. The mountain unleashed numerous powerful flows of hot gas and volcanic matter during its active years.

The Cataclysmic Eruption

The mountain exploded 3.4 million years ago during the Pliocene Epoch. The blast hit with such force that it knocked down every tree in the forest in a southwest to northeast pattern.

Many of these redwoods had already lived over 2,000 years when the eruption struck. The trees fell like dominoes, all pointing away from the volcano’s center.

An Ancient Redwood Forest

The buried trees belonged to Sequoia langsdorfii, direct ancestors of today’s coastal redwoods. Unlike modern redwoods that grow near the Pacific coast, these prehistoric trees thrived further inland.

This difference helps scientists track how California’s climate changed over millions of years. Researchers also found one petrified pine tree among the redwoods, showing the forest had some variety.

Rapid Burial in Volcanic Ash

White ash shot from Mount St. Helena during the eruption. As it cooled in the air, this ash settled over the fallen trees and buried them completely. This quick burial created an environment without oxygen around the wood.

Without oxygen, the bacteria that normally rot fallen trees couldn’t survive. This immediate preservation was the first step in turning wood to stone.

The Chemical Transformation Begins

Once buried under ash, a slow chemical change started. Rain and groundwater seeped through the ash, picking up minerals as it moved downward. This mineral-rich water soaked into the buried trees.

Silica, the main ingredient in glass and quartz, became the primary mineral in this solution. The water carried silica into every part of the wood, setting the stage for preservation.

Permineralization Preserves Cellular Detail

The mineral solution soaked into the trees down to their cells through permineralization. As water dried up, silica and other minerals filled the empty spaces in the wood. These minerals formed a perfect copy of the tree’s structure.

Silica attached to the cell walls and replaced the wood material as it broke down. This process kept even tiny details of the original trees intact.

The Trees Turn to Stone

Over thousands of years, minerals replaced all the wood. The tree molecules disappeared, but their exact shape remained. This change produced stone copies harder than steel.

The petrified wood consists mostly of quartz, one of nature’s hardest materials. For 3.4 million years, these stone trees stayed buried, waiting for someone to find them.

"Petrified Charley" Makes a Discovery

In 1870, Swedish immigrant Charles Evans found something strange while working in his Calistoga pasture. A hard object that looked like a log stuck out from the ground. When Evans examined it, he realized it was stone.

News of his find spread quickly, and locals nicknamed him “Petrified Charley.” His chance discovery soon caught the attention of scientists from across America.

Scientists Confirm the Extraordinary Find

Evans’ find attracted prominent researchers to Calistoga. Yale University paleontologist O.C. Marsh studied the site and wrote about it in 1871. Marsh confirmed these stone logs were actually petrified trees from an ancient forest.

His article brought scientific recognition to the site. Later, UC Berkeley scientist Diane Erwin proved these trees show how redwood habitats shifted over millions of years.

The Giants Receive Their Names

As workers uncovered more petrified trees, the most impressive ones got names. “The Queen” spans 8 feet across and stretches 65 feet long. This giant lived about 2,000 years before the eruption ended its life.

Other notable trees include “The Giant,” “The Pit Tree,” and “The Robert Louis Stevenson Tree,” named after the author who visited in 1880 and wrote about the forest.

Visiting The Petrified Forest of Calistoga

You’ll find the Petrified Forest at 4100 Petrified Forest Road in Calistoga, California.

Two main trails take you through the stone forest – the Main Trail showcases the largest petrified redwoods, while the Meadow Trail offers views of Mount St. Helena, the volcano that buried these giants 3.4 million years ago.

Daily guided tours explain the petrification process in detail. Don’t miss “The Queen,” an 8-foot-wide redwood giant, or the Ash Fall display showing actual volcanic ash from the ancient eruption.

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