Wild About Utah: Petrified
“Charlie climbed onto the bed and tried to calm the three old people who were still petrified with fear. ‘Please don't be frightened,’ he said. ‘It's quite safe. And we're going to the most wonderful place in the world!’
Author Roald Dahl uses the word petrified as being motionless, stonelike, frightfully frozen, as he describes Charlie Bucket’s puzzled grandparents and his own excitement about a trip to Mr. Willy Wonka’s Chocolate Factory.
Utah’s San Rafael Swell rates as one of the most wonderful places in my world, and not because of an abundance of chocolate or gleeful oompa loompas. Beneath the towering spires on my bucket list-quest to see desert bighorn sheep in the wild, I’ve wandered among the petrified wood fragments scattered in the desert sand, so many that I almost forget to appreciate them for what they are.
Petrified wood is a fascinating fossil, colorful evidence that what is now desert was once lush forest. We’ve set aside places like Petrified Forest National Park in Arizona, and Utah’s own Escalante Petrified Forest State Park boasts something like five and a half million tons of fossil wood.
When I adventure through and research Utah’s geologic history, it makes sense that the Chinle layer is a major host rock for petrified wood and uranium in the San Rafael Swell. Let’s go back in time to find out why.
Over 100 million years ago, an ancient sea covered much of Utah. The San Rafael Swell was a large island where tall conifers lined its riverbanks and dinosaurs slogged through its swamps. Evidently, as understood by radiation specialist Ray Jones in a 1997 Deseret News feature titled “Hot Spot”, “uranium isotopes dissolved in water tend to bond chemically with decaying material, like branches and logs.”
Uranium prospectors in the early 1900s would follow petrified branches in the San Rafael Swell to uranium ore-bearing larger stumps buried with almost Geiger-counter precision. It’s no wonder that uranium mines dot the hills and debate continues about mineral resource rights in the area.
The Greek root petro means “rock,” so petrified wood is prehistoric vegetation “turned to stone.” Permineralization is this process when minerals replaced the organic tree material when the organism was buried in water-saturated sediment or volcanic ash. Without oxygen, the logs, stumps, tree rings, knots, and even bark were preserved, giving paleobotanists clues to relationships between prehistoric plants and those we have today. According to Dr. Sidney Ash, we even find evidence of busy bark beetles in the petrified specimens in the Wolverine Petrified Wood area of Grand Staircase-Escalante National Monument.
In “Petrified Wood: Poetry Written by the Earth” released by the Myanmar Geosciences Society, I learn there are sacred shrines erected in Thailand’s petrified forests attracting visitors praying for protection. Thai legend states that touching petrified wood will give a person long life. Charles Darwin also mentioned his fascination with prehistoric plants and upright fossilized tree stumps in his naturalist journals during his expeditions, and we know he gathered and catalogued specimens.
It may be bad luck, however, to move a petrified fossil from where it lies, a superstition shared by many Escalante Petrified Forest State Park visitors who have ignored the “leave only footprints, take only photographs” warnings. It seems that the park rangers receive packages from petrified offenders returning the fossil shards with apologetic notes, wishing they’d just admired the artifacts in their natural Utah settings.
I’ll admit that, had I been able to lift the massive specimen I stumbled upon while I was Behind the Reef this spring, I might have been tempted to take it home. The magic for me, though, is imagining a dense forest once where cactus and rabbit brush now thrive. Whether one uses the word to mean frozen as stone from fear or geologic processes over time, and whether one is searching for uranium or a glimpse into prehistoric biomes, petrified wood is a symbol of long-lasting wonder.