Ginna Allen
News Editor
What if we could travel back in time to see what came before us? A long-term, place-based teaching and research project on the Mountain called “Domain 3D” may allow us to do just that. The project aims to explore the subsurface layers of the Domain through a unique form of seismic, non-invasive technology. After offerings of support by alumni donors and brainstorming by geology and forestry faculty, former Vice-Chancellor John McCardell took the project to the Regents in 2015 where it first came to be.
Vibroseis trucks, or more commonly called “Thumper Trucks,” will arrive in May after graduation to send these seismic waves 7,000 feet into the ground. Seismic data is collected by sending an acoustic signal into the earth and recording the reflected waves at the surface, similar to an ultrasound. This will then give way to an expanse of data that covers much of the Domain, with designated data lines planned to go from the gates in Monteagle to Breakfield Road, and then another from Jumpoff Road down to the Domain’s property lines in Cowan.
With the new data, students and professors can study never-before-seen views of the natural world below, including deposits, fossils and other hidden layers that date back long before Sewanee existed. The seismic findings will also support discoveries and research opportunities for students and faculty years into the future. This will include using the seismic data to identify drilling points to extract deep underground cores as a part of the plan to install a rock core library outside of Snowden Hall. These cores would then provide a lasting source of information and research opportunities that have not yet been available with previously available cores obtained from drilling of 110-foot water wells.
Photo credit by Ginna Allen
“The goal of Domain 3D is to use multiple geoscience data types to characterize the Domain subsurface in three dimensions, from the soil to the basement rock,” stated a briefing paper announcing the project. “Generations of Sewanee students have mapped the geology of the plateau from rock outcrops on the surface and the bluffs, but very little is known about how these formations extend and change in the subsurface.”
Dr. Martin Knoll, Professor of Geology and Chair of the Department of Geology, told The Purple that critical intervals between different rock formations shown in deep ground cores are especially exciting. “The boundary between the Pennington Formation and the Raccoon Mountain Formation is such an important interval because you go from an ocean, a marine deposit, to a land deposit with the swamps and the coal,” Knoll said. “So if you could get a core over a couple hundred feet there, or just a hundred feet, that would be amazing.”
While these technologies are commonly used by oil companies to seek drilling sites, Knoll noted that Sewanee’s seismic scans and core sampling are not in search of a lucrative source of oil or gas. Unlike oil exploration seismic studies, Sewanee’s project will be strictly for advancing education and understanding one of North America’s most diverse ecosystems and striking geologic displays.
Dr. Scott Torreano, Professor of Forestry, hopes the project will allow students to reach beyond what’s here on the Mountain. “This technology lets us look deep into the Earth, and this teaches students about not only what are the technologies available to do that, but also the skills of data interpretation, which is so important. That’s really what we do here in Snowden is we teach students how to interpret and manage natural landscapes, whether we’re here, whether we’re in Yellowstone or whether we’re in Tasmania.”
From its inception, the project has been built to offer students opportunities beyond traditional undergraduate liberal arts offerings. Dr. Knoll described how students will even be able to assist in the set up of equipment for the trucks in May. “We’ll get six to eight current students working to help actually lay out what they call the geophones that will be lined up in the woods and they’re wireless, so that when the shock waves go underground and bounce back up they are recorded by those geophones. The big thumper truck drives down the road and it’s got a big plate underneath it. They drive on the road’s shoulder, and they stop every few feet and they drop the plate. As the shockwaves hit different layers on the way down, some of them bounce back up, and that’s all recorded. And from that, you can make a detailed image of the stratigraphy and the layers,” Knoll said.
The unique experiences that the project will offer students — from fieldwork, to core retrieval and study, to data processing and evaluation — will equip them for life after graduation. “This technology, which is developing constantly, is very much like what our students would use when they move into the fields of geology, natural resource management and forestry,” Torreano said.
The project is the result of years of extensive work and planning. Efforts have been put towards inventorying forests and surrounding fauna, along with using Lidar technology to gather topographical data on the Domain. Similarly, the community announcement noted how “the first phase of the initiative from 2015 to 2020 yielded extensive data sets focused on the very shallow subsurface. These data have been used by faculty and students in geology, forestry, archaeology, and environmental science.” There was also a study a few years ago that involved collaborative efforts of Sewanee and the University of Texas to profile a hundred feet below the surface as a part of the larger Domain 3D project.
So, as preparations continue for the thumper trucks to arrive in May, the possibility of understanding the Domain’s past becomes a reality. “As the drill bit spins,” Knoll said, “you’re cutting through these sand grains from an ancient delta, and then you’re getting down to the limestone from an ancient seafloor, down, down, down, back in time.”