Identifying a geological fault in the earth’s sub-surface might seem above the expertise of most college-age kids, but geology students at BYU are learning that it’s definitely doable.
Students have been working with professors John McBride, Steve Nelson, Dave Tingey, and Department lab manager Kevin Rey in an outdoor-size laboratory—the Sevier Desert in central Utah—learning about the different kinds of faults there. Students can observe active geology within a couple hours’ drive from BYU.
“We can take students out and show them a range of geological phenomena,” McBride said. We can show them active faults, we can show them geologically recent lava flows that interact with the faults. . . . It’s a good place to show students a range of geologic processes as they are happening.”
McBride compared recognizing a fault to breaking a brick with a hammer, then displacing the pieces and putting the brick back together with the layers misaligned. Images of the layers of earth around a fault would look similar to the interior of the brick.
“You notice . . . the layers of the brick don’t line up,” he said. “So geologists look for these offsets to identify a fault. That’s how you identify a fault in the first place: something doesn’t match.”
While BYU professors have been taking students to the Sevier Desert for more than 30 years, McBride, Nelson, Tingey, and their students have been studying specifically the variation of geological deformation in the area. They use sound waves to create images of what the earth looks like below the ground surface.
With these images, they can recognize relationships between different deformation episodes and rock layers and determine whether or not the fault is active. McBride said in the language of geology, “active” is a relative term, but it has to do with whether or not the land is changing enough—or has the potential to change enough—to be hazardous to human life and infrastructure.
If the earth hasn’t had time to erode away a deformational feature like a fault scarp (an embankment or ridge), it may have happened recently enough to be of interest to building planners, as well as geologists.
“As soon as you produce an elevation in topography, nature wants to erode it away,” said McBride. “So if you see a landform related to faulting that’s still there, that means that it’s geologically recent.”
In the case of the Sevier Desert, visible fault scarps mean that the geological deformation is relatively recent.
“We know we have an active geological process because that scarp is still there,” McBride said.
The BYU research group has concluded that the Sevier Desert faults are part of a complex system, linked together throughout the area. In certain places, the land continues to deform by a “creep process,” slowly and gradually.
McBride came to BYU in 2002 from the Illinois State Geological Survey and the University of Illinois at Urbana-Champaign. He has emphasized the difference in the dramatic geology that can readily be found in Utah to the subdued surface geology found in Illinois. The rugged mountainous landscape of Utah is evidence of recent geological activity.
“Utah has a lot of active faults and geological activity, and nature hasn’t had a chance to remove all of it.” He said. “Mountains eventually get eroded away, ‘shall be made low,’ as it says in the Bible. The high places will be made low and the valleys exalted. Everything gets evened out.”
Until that happens, McBride and his students will continue to use the visible geology in the Sevier Desert for all its worth.