Professor, students study carbon-rich rocks for clues to mass extinction
The burrows of ancient, squishy animals, preserved in what now is black shale in Upstate New York, may tell SUNY Oswego paleontologist Diana Boyer and some of her students part of a story of marine life extinction more than 300 million years ago.
Boyer, an assistant professor in the college’s earth sciences department, recently won a $50,000 American Chemical Society grant to help her and students investigate oxygen levels in Late Devonian black shale—brittle rock in thin layers made of inland sea sediments in prehistoric times.
“The theme is: Why was there a mass extinction?” Boyer said. “There was massive loss of life across the board. We are testing low oxygen levels as a mechanism for the extinction.”
A traditional fossil record largely is not part of this project, she said. Many marine animals of the Late Devonian, living in a shallow sea across New York and the Appalachian basin, didn’t have bones or shells. But they did burrow through sediments whose chemical composition gives clues about how much oxygen was in the water of that period.
Lab, field work
For the study, geology majors Ellen Wilcox and Marc Collins join Boyer in the rock preparation lab in the basement of Hewitt Union, where they cut and polish samples of black shale. The layers are so thin and brittle that the rocks have to be duct-taped before study can begin. The students wet the smoothed face of each rock to examine subtle features, such as flaws that can be animal burrows or discolorations that can indicate oxygen levels.
What makes black shale black? Wilcox vividly recalls coming home from rock-collecting trips smelling like oil, because of the high carbon concentration in the rock. It’s indicative of low to no oxygen in the sediments that created the layers.
Before scientists can speculate on causes for the oxygen deficiency, researchers have to decide whether there really was no oxygen in the ocean 300 million years ago.
Boyer, who has studied the Late Devonian die-off for years, said her research shows there were low levels of oxygen, alternating with periods of higher levels. “I think it’s more of an off-on mechanism,” she said. “Perhaps this study will help us understand the mechanism.”
The paleontologist suggested some implications of her work for today’s environmental challenges. “In today’s oceans, there are lots of areas where, through human impact, there are low levels of oxygen,” Boyer said. “Understanding the historical record can help us understand the impact on bays of Long Island Sound and Chesapeake Bay, for example—help us better understand the biological response.”
Wilcox and Collins began working with Boyer under the college’s Summer Scholars Program.
Collins, a junior who also has a minor in physics, said he joined two expeditions this summer to collect samples in shallow streambeds southeast of Buffalo. Black shale also is familiar as the face of waterfalls in Letchworth State Park and in the Ithaca area.
Wilcox, a senior who minors in mathematics and philosophy, is working on a senior capstone research project that overlaps Boyer’s research.
“I was never a geology major before,” Wilcox said. “One of my favorite parts about switching to this department is that it’s small enough we have all kinds of opportunity to work with professors.”
Wilcox plans to make a presentation next spring at Quest, SUNY Oswego’s day of celebration of student and faculty scholarship. Boyer, who is starting her third year at the college, said the goal of her study is publication in a peer-reviewed journal.
PHOTO CAPTION: Diana Boyer, left, assistant professor of earth sciences, and geology majors Marc Collins and Ellen Wilcox work with black shale samples as part of a study funded by a new American Chemical Society grant. They look for clues to oxygen levels in the 300-million-year-old sediments that formed the rocks, part of the effort to understand what caused a mass marine extinction.
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(Posted: Sep 16, 2010)