Petrified Forest

Deep in the rugged foothills of the Mayacamas Mountains, the Petrified Forest of Calistoga stands as a silent, stone-carved testament to a cataclysmic moment in Earth’s history. Located just a few miles from the steaming vents of Old Faithful Geyser, this site is famous for containing the largest petrified redwood trees in the world. Unlike many other petrified forests where the wood has been transported by water over long distances, the specimens here were preserved exactly where they grew millions of years ago. To visit this forest is to walk through a "fossilized snapshot" of a prehistoric ecosystem, frozen in time by the very volcanic forces that created the surrounding Napa and Sonoma valleys.

The geology of the forest dates back approximately 3.4 million years to the Pliocene Epoch. The preservation began with a massive eruption from nearby Mount Saint Helena, which unleashed a devastating pyroclastic flow—a fast-moving cloud of superheated ash and volcanic gas. This flow flattened the massive redwood forest, burying the trees instantly in a layer of ash that excluded oxygen and prevented decay. Over the ensuing millennia, silica-rich groundwater permeated the buried logs, gradually replacing the organic wood fibers with quartz crystals in a process known as permineralization. This slow chemical exchange was so precise that the intricate details of the wood—including bark textures and annual growth rings—were preserved in stone.

The discovery and history of the facility are as colorful as the stone trees themselves. The site was first unearthed in 1870 by a French immigrant named "Petrified Charlie" Evans, who noticed a hard, stone-like stump while clearing a pasture. Word of his discovery spread quickly, eventually reaching the famous author Robert Louis Stevenson, who visited the site in 1880 and immortalized it in his travel memoir, The Silverado Squatters. Since 1914, the forest has been protected and managed by the Bockee family, making it one of the oldest privately owned natural landmarks in California. Their stewardship has ensured that the site remains an educational sanctuary rather than a commercialized roadside attraction.

The facility offers several distinct trails that allow visitors to examine these giants up close. The most famous resident is the "Queen Tree," a petrified redwood measuring over eight feet in diameter and sixty-five feet in length. Another remarkable specimen is the "Giant," which stretches eighty feet long and provides a clear view of the massive scale these trees reached before the volcanic disaster. Along the paths, the facility features museum displays that explain the difference between the ancient Pliocene flora and the modern trees that now grow above their buried ancestors. The contrast between the living, green canopy and the grey, mineralized logs below creates a profound sense of deep time.

Beyond the sheer size of the logs, the Petrified Forest is home to unique paleontological details that intrigue researchers and tourists alike. Scientists have identified not only redwoods but also fossilized pine and oak, suggesting a more diverse climate in the prehistoric Napa Valley than exists today. Furthermore, the presence of ash layers visible in the hillside excavations provides a clear stratigraphic map of the eruption event. As visitors leave the shade of the modern forest to stand beside a tree turned to solid rock, they are reminded of the fragile boundary between life and geology. It is a hauntingly beautiful destination that captures the explosive and transformative power of the California landscape.

Fun Facts

The petrified logs at this site often contain obsidian, quartz, and opalescent materials, creating, in some cases, partially opalized wood.

Attraction Advice

Petrified Forest is open daily from 10 AM to 5 PM. Visitors should arrive by 4 PM to complete the trail before closing time. Admission is $14 for adults, $13 for seniors, $8 for students, and $6 for children 6 and older. Age 5 and under is free.