Emerging research on the Tetons’ geologic past might hold important implications for the future.
On Tuesday the Geologists of Jackson Hole club will host Ryan Thigpen, assistant professor of earth and environmental sciences at the University of Kentucky, to give a talk about emerging research on the geologic history of the Teton Range and the implications for future hazard planning. The talk will begin at 6 p.m. in the Ordway Auditorium at Teton County Library.
Thigpen and his wife, Summer Brown, have been working since 2008 on a hypothesis about the timeline of geologic events in the Teton region. Their research suggests the migration of the Yellowstone hot spot is responsible for erasing a northern section of Tetons.
“Rather than the hot spot causing the mountain range to form, we’ve almost flipped it the complete other way, where the mountain range actually forms and then the hot spot comes in and wipes it out,” Thigpen said.
Geologic models show both that most of the fault uplift that created the Tetons occurred about 17 million or 18 million years ago and that the Yellowstone hotspot migrated to its current location about 2 million years ago, meaning it can’t be responsible for creating the Tetons.
Across the Snake River Plain and along the migration route of the Yellowstone hotspot, Thigpen said, mountain ranges with origin stories similar to the Tetons’ seem to be abruptly cut off.
“It almost looks like a giant pencil eraser just coming through and erasing the topography,” he said.
In the past, other geologists have suggested that the hotspot may have removed the northern section of the Tetons, but those speculations have remained hypotheses.
“This might be our first chance to definitively prove that this actually has occurred,” Thigpen said.
To do that Thigpen and Brown have been collecting data about all the slip events along the Teton Fault, both to map the history of the fault and to understand its present-day length and seismic activity.
Thigpen said that when faults accumulate displacement, or the plate on one side slips under the plate on the other, they expand. He and Brown have found the amount of displacement in the Teton Range to be more than what geoscience would suggest based on the length of the Teton Fault as it’s currently understood.
They have also found that the biggest displacement along the range is actually not at the Grand Teton, where people think the center of the fault is, but at Mount Moran, suggesting a center farther north.
If the fault does continue farther north, that would help to prove there were once mountains there that have since been erased.
“It takes tens of millions of years to get rid of a mountain range in the fastest case, so to have one disappear in just a couple million years, if that’s what really happened, is really incredible,” Thigpen said.
Besides being an exciting scientific discovery, the research could influence hazard planning in the region. If the fault does extend farther north, and if Thigpen and Brown find that section of the fault to be still active, it could have implications for earthquake mitigation.
Thigpen is careful to highlight that their findings and their hypothesis are still in the preliminary stages, and they have a lot of work left to do.
Still, Thigpen said his and his wife’s initial findings are exciting. Geologic data sets tend to be imperfect and difficult to interpret, but the data they have collected has proved the opposite.
“This has been one of the coolest geology projects I’ve ever gotten to be a part of, because things just keep working out,” Thigpen said. “Some of this stuff has lined up so well that it almost makes us uncomfortable.”
A team of interdisciplinary researchers from the University of Kentucky joined Thigpen and Brown in Jackson for the first time last summer. They will return to Jackson in July and August to collect cores on both sides of the fault where it runs under Jackson Lake. Those efforts are intended to date the seismic events and confirm that they line up with what has previously been documented.
It’s an exciting time to be doing work on the Teton Range, Thigpen said. There is a lot of energy around this research and a lot of people traveling to the area to contribute.
“We’re seeing a lot of the old guard and a lot of the new folks coming together doing all these really interesting multidisciplinary things,” he said.
“It’s sort of a modern-day geological renaissance, if you will.” ￼