Hike Yellowstone National Park’s Fossil Forest

Petrified trees
See what the climate was like in Yellowstone Country 50 million years ago on this hike through Fossil Forest.

The Skinny:
START: Four miles east of Tower Junction on the Northeast Entrance Road (last pullout on the right side (SE) of the road before crossing the Lamar River). There is no trailhead sign nor is there a marked trail to follow. Therefore, it is important that you spot your destination before leaving the highway. As you drive east along the Northeast entrance Road, you will pass a number of small glacial lakes about 2.5 miles from Tower Junction. Look ahead on the right (SE) to Specimen Ridge. Near the top, you should be able to pick out two large outcroppings of brown dirt, separated by a patch of trees that rise to the top of the ridge. Near the top of the east outcropping lies a fine collection of fossilized trees. If you have binoculars, you should be able to spot some of the stumps that protrude from the bare cliff. On your TOPO map this area lies just northeast of the letter ‘p’ in the word ‘Specimen.’
END: Same as start.
DISTANCE: 3 miles
ELEVATION CHANGES: A steep 1,100 foot climb.

TIME REQUIRED: 3.5 hours

Leave the highway, cross the sagebrush flat, pass a number of large granite boulders (left behind by glaciers) and climb the open meadow to the top of the ridge that runs northeast from the desired outcropping. Once on the ridge, you should have no trouble following a fairly well traveled trail up the ridge through a stand of trees and out to the Fossil Forest area. You will first spot a huge petrified stump with two tall petrified trunks just below. The huge stump is the remains of a giant redwood tree. It has a circumference of 26.5 feet and probably stood 200-300 feet high when living. The two trees below are pine. An early visitor to the park’s Fossil Forest once commented that they “stand like columns of a ruined temple.”

Around 55 million years ago, Yellowstone entered a volcanically active phase. Ashes, mudflows, and breccia from the vicinity of the Absaroka Range entombed the trees that were thriving in this area.

As the volcanic matter cooled, cracks formed and water seeped through. This water picked up silica from the surrounding rock and was then soaked up by the tree material, causing the silica to be deposited in each dead tree cell. Over a long time the tree decayed away entirely, leaving only the hard rock behind. Much later, glaciers excavated these specimens as they cut through the Lamar Valley.

The fossilization is very extensive, and it is even possible to count the growth rings and observe the microscopic details of the trees’ cellular structure. Geologists have pieced together an entire forest containing over 100 different types of vegetation. The most prevalent trees discovered include: walnuts, magnolias, maples, oaks, redwoods, dogwoods, and pines. From this it is clear that Yellowstone 50 million years ago had a drastically different climate, probably lying no more than a few thousand feet above sea level and receiving 50-60 inches of rain each year. Thus, Yellowstone’s fossil forests provide geologists with a “window to the past” that cannot be matched anywhere in the world!

Another factor that makes Yellowstone’s Fossil Forest unique is that many of the specimens are still standing in upright positions with their roots imbedded in the ground right where they grew millions of years ago. This rarely occurs in other fossil forests.

Before descending through the fossil area in search of other specimens, you should make a short side trip to the top of Specimen Ridge. It’s an additional 200-foot climb, but the spectacular views of Mount Washburn, the northern terminus of the Grand Canyon of the Yellowstone, and some beautiful open meadows make it worth your effort.

Professor Erling Dorf of Princeton has theorized that these specimens do not merely represent one entombed forest but rather include trees from 27 separate forests (the most in the world), each stacked on top of the other, layer by layer, to a thickness of 1,200 feet. He explains that the Absaroka volcanism lasted for 15 million years. In that time, there were alternating periods of activity and dormancy. The active periods caused trees to be encased and eventually fossilized. During the ensuing dormancy, new trees grew up on top of the old, only to be encased by the next volcanic activity. Thus, as you make your decent, you are really passing through many different forests, each older than the last.

Mountain men who visited the Yellowstone region created tall tales concerning these petrified trees. They claimed a Crow Indian Medicine Man cast a spell upon this mountain and instantly everything turned to stone. There were petrified trees still standing in their original positions. There were petrified bear, and moose, and elk standing just as they were when caught by the petrifying force. There were petrified birds… still in flight… singing petrified songs; and petrified flowers which smelled of a petrified perfume. Even the sun and moon shone upon this mountain with a petrified light. From this story, one could easily have accused mountain men of being petrified liars.