Rock likely 2.87 billion years old

John Foster, curator of paleontology at the Museum of Western Colorado’s Dinosaur Journey in Fruita, holds a rock chunk from western Wyoming. The exterior looks more like petrified wood than native rock.

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Christopher Tomlinson

John Foster, curator of paleontology at the Museum of Western Colorado’s Dinosaur Journey in Fruita, holds a rock chunk from western Wyoming. The exterior looks more like petrified wood than native rock.

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Monday, January 2, 2012

While rocks have been pulverized into sand, fired to incredible heat or have simply withered away, worn down molecule by molecule, a chunk of rock that lay unchanged for nearly 3 billion years is now in the custody of Dinosaur Journey.

The rock, hacked from a boulder in Goldman Meadows Formation in the Wind River Mountains of western Wyoming, was formed on the bottom of a primeval, surreal ocean and was thrust to the surface as part of the core rock of what was to become North America, said John Foster, curator of paleontology for Dinosaur Journey, a branch of the Museum of Western Colorado.

“North America is made up of a number of the big chunks of these pre-Cambrian rocks that got kind of all mashed up together,” Foster said.

To be sure, the rock, which was sliced and polished by the donor to the museum, typifies the kind of molten twisting and pressure of the earth nearly 2.9 billion years ago.

Its exterior looks more like petrified wood than native rock, but a look at the cross-section shows it’s layered like a thick caramel poured out and folded in on itself.

So, it might well have been the more precise 2.87 billion years ago that the rock took its shape, Foster said.

Then, the atmosphere and the oceans were nothing as they are today, Foster said. The iron-laden rock took its shape before it slowly was driven upward toward the surface of the Earth.

It’s largely the same as it looked when it cooled, Foster said, noting it had metamorphosed little, if at all.

At 2.87 billion years of age, the rock predates dinosaurs, even the first trilobites, he said.

The only life reflected in such rock was in tiny bacteria and similar organisms, Foster said.

Foster hopes to place the rock on display later in 2012, once a display of Tyrannosaurus Rex teeth is returned to its owner.