Uncovering the Back Story of Earth's Varied Landscapes

Karin Lehnigk’s interest in geology was first piqued during her family’s frequent hikes around northern Virginia, where she grew up just 20 minutes outside of Washington, D.C. She was hooked on the subject after a high school internship at the U.S. Geological Survey near her home, where she studied microfossils in sediment cores from the ocean floor.

“It can be really tedious work, but I found it extremely fun. It was like, ‘Wow, this stuff was on the ocean floor for millions of years and I’m the first person to see it,” said Lehnigk.

She went on to do her undergraduate studies in geology at William & Mary, during which she traveled around her home state learning about the different landscapes that shaped the cultures, industries, and economies of each region. For her graduate studies, she was drawn to UMass Amherst after learning that Isaac Larsen, assistant professor of geosciences in the College of Natural Sciences, was studying the Channeled Scablands in eastern Washington state, a landscape that had long fascinated her.

The Channeled Scablands are notable for their giant canyons and eroded topography, created by massive floods at the end of the last Ice Age, around 21,000 to 15,000 years ago. Lehnigk became part of Larsen’s first cohort of students, and has spent the past several years exploring the question of how large the floods had to be to carve the canyons present today. They try to answer this question by running computer simulations of floods, and collect samples from rocks transported by floods, to measure how long they have been sitting on the surface of the landscape.

“While at UMass, Karin has mastered two very different skills—numerical flood modeling and isotopic dating—and is using those skills to determine both the magnitude and timing of some of the largest floods known on Earth,” said Larsen, who is Lehnigk’s graduate advisor. “Her work is addressing big questions regarding the role ice age floods played in shaping Earth’s topography.”

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You’re here for four to six years; make the most of it. I think I can say that I’ve done that, and that’s a pretty good feeling.

Karin Lehnigk

While the Channeled Scablands are interesting to study on their own, Lehnigk explained that understanding the circumstances that formed them can also shed light on other landscapes.

“Today, we see these same types of floods at work on a smaller scale in places like Greenland and Scandinavia, where climate change is producing conditions similar to what was going on when floods were occurring in the Channeled Scablands,” she said. “The Scablands are also frequently used as a reference point for landscapes on Mars, where we see similarly shaped and sized canyons. If we know how big a flood needs to be to carve these canyons on Earth, we can extrapolate to how large floods may have been on Mars in the even more distant past.”

Lehnigk has had the opportunity to study Mars herself through a six-month internship at the Smithsonian National Air and Space Museum (NASM). In spring 2017, she received a National Science Foundation (NSF) Graduate Research Fellowship (GRFP), which provided funding for three years of graduate education and made her eligible for other opportunities through NSF. In 2021, she was awarded funding from NSF’s INTERN program, which enables graduate students to get research experience and training in a non-academic setting. In her NASM internship, Lehnigk is running computer simulations of ancient floods on Mars to figure out how big they were and where the water might have come from.

“Geoscientists and planetary scientists do a lot of similar work, but don’t often talk to each other,” said Lehnigk. “I thought it would be cool to bring the main finding in our study of the Channeled Scablands—which is that you can carve canyons on Earth with smaller floods than what it would take to fill them up all the way—and see what the implications are for Mars.”

In addition to her academic work, Lehnigk has been involved in the Department of Geosciences’ efforts to address issues of diversity and accessibility, in connection with a worldwide effort known as Unlearning Racism in Geoscience (URGE).

“Our department has been putting a lot of thought, effort, and action into making sure that labs are accessible and that everyone can be safe when they’re out in the field,” she said.

Lehnigk plans to defend her thesis in spring 2022. After graduating, she hopes to continue working for the government in some capacity.

Reflecting on her graduate career, she described her attitude as, “You’re here for four to six years; make the most of it. I think I can say that I’ve done that, and that’s a pretty good feeling. I really look forward to what’s next.”

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This story was originally published in November 2021.