Marcie Occhi (B.S. ’09, M.S. ’11, geology) digs her work mapping the ancient history of Virginia’s rocks and minerals.
Sometimes a career path winds its way to you rather than the other way around. That’s what happened to Marcie Occhi (B.S. ’09, M.S. ’11, geology), who supervises geologic mapping for the Virginia Department of Energy.
“I graduated high school at 16, and I wasn’t ready at that point to decide anything about the future,” she said. “So, I spent four years dabbling in all kinds of things at community college, trying to figure things out.”
To complete her associate’s degree at Anne Arundel Community College, Occhi was required to take a lab science. Meteorology sounded intriguing.
“But meteorology was full,” she said. “Geology had openings.”
For Occhi, that shift in plans proved life changing. Not only was the physical geology course taught by University of Maryland alum Alicia Siegrist (B.S. ’75, geology), “it was the first time I couldn’t wait to attend class, couldn’t wait to dig into the homework,” Occhi said. “That’s where my love for geology started.”
UMD beckons
Occhi knew she’d need an advanced science education to pursue geology professionally. She was already intrigued by UMD because of Siegrist’s connection to the university, but a trip out west gave her the push she needed to apply.
“I went to visit my brother in the Teton area of Wyoming, and we went rafting down the Snake River with this wonderful guide who had a geology background,” she recalled. “He was talking about all these rock formations and how the river responds to different forces, ultimately shaping the landscape. I get goosebumps now thinking about how momentous that experience turned out to be.”
Occhi applied and was accepted to UMD soon after that. She knew the geology program would be rigorous.
“It requires a senior thesis research project that most universities don’t ask undergraduates to do,” she said. “That turns out to be an incredible opportunity to work directly with faculty on interesting projects, which benefits the students in so many ways.”
As an undergrad, Occhi investigated how rain, runoff and groundwater discharge move through the Anacostia watershed with Karen Prestegaard, an associate professor in the Department of Geological, Environmental, and Planetary Sciences.
“We collected a lot of novel data using stream gauges to figure out how impervious surfaces like paved roads change the routes water takes into streams during storm events,” Occhi explained. Such data can also help scientists trace pollutant movement, she said.
To complete the research, Occhi decided to pursue her master’s at UMD. But first she returned to Wyoming to take a special field-methods course with the University of Wyoming.
“I loved being out there camping and learning what I thought was a bygone art—mapping the geology using paper maps, hammers, drills and little hand lenses,” she said.
The hands-on course honed skills Occhi later applied during her master’s at UMD, then to her Ph.D. research at the University of Pennsylvania—analyzing stream sediments in the Luquillo Critical Zone Observatory in Puerto Rico—and finally in her work with the state of Virginia.
“Much of my career has been spent drawing detailed geologic maps, using mapping and graphic design software, that show in two dimensions the different rocks and sediments at Earth's surface and how they relate to one another,” she explained. “They also communicate information about natural resources, mineral potential, legacy mining, water resources and geologic hazards like landslides.”
What has changed most over the years is how the team presents the data to clients and the public.
“Nowadays we package our map data into digital formats for people to ingest into their own spatial software systems,” she said, “but we still make printable maps—the old-fashioned paper kind.”
In one especially memorable map-making project in partnership with the U.S. Geological Survey, Occhi helped to describe an entirely new terrane—a crust fragment formed on one tectonic plate that later fused to another while retaining its own geologic history—in Virginia’s Piedmont region.
“When you're making a geologic map, there's flexibility to investigate something that is interesting to you,” she explained. “In this case, there was one band of rock that everybody lumped together as one unit with what was around it. But the age data told a different story, so we took more samples and investigated further.”
The new terrane lies in an area hundreds of millions of years older than the surrounding rocks.
“This sort of discovery helps us better understand the order in which things happened as the continent formed, refining our knowledge of the relationship between the rocks under our feet,” she said.
No walk in the park
Now the supervisor of the mapping section in Virginia Energy’s Geology and Mineral Resources program, with a focus on the state’s Piedmont and Coastal Plain provinces, Occhi has found that mapping in Virginia has special challenges.
“In the Appalachians, you have three different mountain-building signatures—the overall configuration, orientation and geometric arrangement of the rock’s internal components—which are shaped by three episodes of continental collision and reported in distinctive mineral content and physical fabric,” she explained. “Having these stacked imprints can make it tricky to interpret things like which fabric came first. I like to think that if you can map the complex geology in Virginia, you can map anywhere else in the world.”
She describes her team’s work—which is used in developing mineral, energy and water resources, land-use planning and environmental protection, erosion mitigation, predicting natural hazards and more—as multiple sciences packed into one.
“Geology borrows from physics, chemistry, biology and math; it’s this wonderful conglomeration that uses the other hard sciences to understand the Earth,” she said.
Occhi’s work lets her dig deep into the origins and evolution of Virginia’s rocks and minerals. But her favorite natural form in the landscape isn’t land at all.
“I have a special fascination for rivers,” she said. “They’re such a formidable force in shaping the land. That rafting trip in Wyoming introduced me to their power, and I’ve been rapt ever since.”
That’s why when she’s not working, “you’ll probably find me exploring the local rivers,” she said. “I love teaching my kids about how rivers, pulled by gravity, are rain’s conveyor belt to the ocean, shaping the continent as they flow.”
