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Petrified Wood from the Miocene Era

Miocene Forest
How Fossils Are Made

The Miocene Forest, located in the Helen N. Jewett Basalt Gallery, features 15-million-year-old trees. They were dug out of a ridge in the Yakima Valley and rebuilt inside the museum. A mural showing Yakima during the Miocene era surrounds the trees, and you can examine polished cross-sections of different types of petrified hardwoods. This unique exhibit provides a glimpse of prehistoric Yakima.

While grading his Yakima Ridge property for a new driveway in 2003, Clyde Friend struck something harder than basalt with his excavator. He had no idea that this was only the tip of the iceberg—or, more accurately, the top of the tree trunk! He had discovered the first of many tree trunks that would transform his backyard into "a forest of stone." Two years later Clyde shared his discovery with the Yakima Valley Museum...and so began the planning for The Miocene Forest.

The forest represents something truly unique in the display and understanding of petrified wood. Instead of displaying the fossil wood as geology specimens, alongside other rocks, this exhibit uses these fossilized trees as evidence of the past world that was the Yakima Valley. It was a mixed hardwood forest that existed in a warm, wet temperate environment over 15 million years ago (similar to forests that exist today in the American Southeast).

The exhibit is also unusual because it displays the trees standing up—just as they were found. Of course, when the trees died they eventually fell over, but later movement of the earth pushed them upright again.

In addition to fossil wood, our museum also has fossil bones of various animals that existed in this same ancient world. A prehistoric horse (Equus simplicidens) and camel (megatylopus), an ancestor of the sabre-tooth cat (pseudaelurus), a giant ground sloth (megalonyx), and a strange pig-like beast with no living descendants (oreodont). Their fossil bones are on exhibit in the museum's Time Tunnel, but they can also be seen in a painting in the Miocene Forest exhibit.

The exhibit itself is stunning—several petrified tree trunks stretch over twenty feet high. Behind these, a cave-like niche opens a window into the Miocene Forest. A large mural depicts a dark forest extending into the distance, with beasts hidden in the shadows. In front of this niche, replicas of living tree trunks paired with polished slices of fossil wood describe a forest filled with ancient relatives of hickory, locust, maple, oak, elm, fir, and sweet gum trees. Across from the niche, is a massive one-ton fossil stump of a honey locust tree, complete with petrified bark, splinters, and sap.

This exhibit took more than two years to produce and required the cooperative efforts of many people with varied knowledge and skills. For scientific accuracy, we consulted with paleobotanist Tad Dilhoff and geologist Nick Zentner. For advice on installing the massive specimens, we turned to structural engineer John Tate. Construction wizards Kip Fletcher and Jerry Orthmann of G.H. Moen Construction reassembled and installed the large trees.

None of this would have been possible without a grant from the M.J. Murdock Charitable Trust and the generous support of many donors, who provided the funds to purchase the fossil wood specimens.


What is Petrified Wood?

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Miocene Forest Petrified Wood
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