Skip to main content

School of Mines Paleontologists Visit the Petrified Giant of Perkins County

Email share

"This is a huge, huge tree," says Dr. Darrin Pagnac. "Just eyeballing it, I'm thinking seventy, eighty feet long. And we are in what's called the Hell Creek Formation -- a series of rocks up here in Northwestern South Dakota that was deposited about sixty-five to seventy million years ago, during the end of the age of dinosaurs, the same group of rocks where we get things like Tyrannosaurus Rex, Triceratops, Hadrosaurs. We get all of them here. So this would have been a tree that was around at that time period."

Dr. Pagnac and Dr. Sarah Keenan, both paleontologists/geologists at the South Dakota School of Mines and Technology, recently visited the site of the enormous petrified tree in Perkins County. Locals have been aware of the tree since sheep ranchers George Jesfjeld and Charles Murphy discovered it in the 1930s. 

"Clearly this tree fell down in a part of the world back then where it was sort of quiet," explains Pagnac. "There wasn't a lot of rapid water flowing through. It probably didn't fall on a hillside because it would've rolled down and broken up. So this is really special in that you have a tree that is this intact, is this huge. So there is something unique about the preservation, about where it fell, and it had to have been buried fairly rapidly. Otherwise it would have deteriorated and fallen apart. So really this is a miracle of fossil preservation here. The chances of this happening are really, really, really slim."

The tree may have been a Metasequoia redwood, an ancestor of the giant redwoods in California. The environment in which it thrived was much different than what exists here now. 

"Hell Creek in general, I think was about seven to nine degrees warmer than it is today," says Keenan. "Much warmer than today. And you would have had a lot of access to water, which the tree needed to grow and you would have had a lot of other really cool vegetation around as well. So think a large flood plain area with these really large metasequoia trees. You also had a lot of fig trees. Those are really common in the hell Creek. So it was just a much warmer, much more humid, environment than we have here today."

Keenan said more may be learned about this tree with further study. "You can create thin sections of chunks of this tree. And from that, you can look at the microstructure and see what's actually preserved. What features still remain from the original tree itself? It would be really cool to have a masters student come out here and do a study on what was the exact environment, what other information can we get from it? How was this actually fossilized? What was the chemical process that led to the preservation of this tree? And so we could do that both by combining the thin section work and looking at what the minerals are and clearly identifying them and then trying to think big picture, like how do you get that mineral forming within this rock? And what would it have looked like in terms of the water and chemistry and stuff like that."

Keenan said finding a tree this well preserved is very rare in the Hell Creek formation. "It got really lucky. Cause you think about, you go hike in the Hills and you see a tree that falls and it dies. That tree starts to break down over time. So you have to have the right conditions, especially in an environment that's warmer and wetter, to prevent it from being degraded by fungi and bacteria. That's their job. So the fact that this entire thing was preserved really speaks to the unique environment that had to be present in order to preserve and protect it, like winning a lottery. It's the tree lottery."

Through the years, there were efforts to excavate the giant tree, which is partially buried on a small parcel of state land managed by the School and Public Lands program. "There was discussion about getting the tree hauled out of there and placing it somewhere else where the public could view it," says Mike Cornelison, Land Agent for School and Public Lands. Those discussions seem to have dwindled by the late 1960's.

Dr. Pagnac recommends leaving it where it lays. "Honestly, I'd leave it here. It's covered up enough that it's safe. Fully excavating it is going to expose it to the elements and that's going to make it erode away quicker. So I would actually probably keep it where it is. It's lasted this long, it's not going to go away overnight. And any science that we could do on it, we could do with little hand samples that aren't going to really detract from the overall appearance of this thing."

So stay tuned. SDPB will keep you posted as more is learned about the petrified giant of Perkins County.

Petrified Giant: The Almost Forgotten Petrified Tree of Perkins County