Have you ever thought about time travel? Though the future may be hard to see, in Yellowstone opportunities abound to glimpse the past. Specimen Ridge, east of Tower Junction, is home to the world’s largest concentration of petrified trees. Over 100 fossilized plant species have been discovered over 40 square miles.

The fossil forests were created 50 million years ago when a series of volcanic eruptions covered live trees in ash, mud and debris. Deprived of oxygen, the wood was prevented from decaying. Silica soaked up into the trees, filling spaces among wood cells and then hardened to stone. Erosion by glaciers, water and wind is slowly uncovering them.

One excellent specimen is easily accessible at the Petrified Tree exhibit. Here, an ancient redwood stands upright, frozen in time. It is enclosed in a fence to protect it from the tragic fate of other petrified trees nearby that were completely removed piece by piece by thieves collecting illegal souvenirs. Another petrified stump has been placed in front of the Albright Visitor Center at Mammoth. Look closely and you will see the trees rings preserved in the stone.

The forests of stone are direct evidence of Yellowstone’s violent volcanic past but when you look closer, they reveal even more about the ancient landscape. The petrified trees aren’t lodgepole pines like the trees currently blanketing the park. Some of the petrified trees are sequoia, maple, dogwood, magnolia, walnut, hickory, oak and breadfruit—deciduous trees of a much warmer, wetter climate than we have here today.

The volcanic nature of this place has been known to obliterate the landscape and yet it has preserved some aspects for us to experience millions of years later. Please remember, it is illegal to remove any features from the park. The park belongs to all of us and we’d hate to rob future generations of a rare peek at the past.