Hear directly from four of our graduate students as they talk a little about what drives their research curiosity and how they're working to investigate a wide range of probing questions about the natural world.
During my PhD research in the Weiss Paleomagnetism Lab, I have been working to understand what magnetism can tell us about the evolution of stars, formation and evolution of planets, and conditions for the emergence of life. I focus on the magnetism recorded in micrometer-sized rock inclusions.
Magnets are everywhere. Our very own Earth is a massive one that produces a large-scale magnetic field detectable at the surface of our planet; its time origin, however, is unknown. Magnetic fields produced by planets can help shield their atmosphere from solar winds and radiation. This has immediate consequences for habitability conditions relevant, for example, for the early Earth. Understanding the timing of Earth's magnetic field can help constrain the conditions during which life emerged. Because very little of the rock record from the first billion years of the Earth is available, we have to use what we can—in this case, micrometer-sized minerals four billion years old—known to be the only survivors of these early years. The magnetic fields from these minerals can only be measured with a few magnetometers, like the one in our lab.
Another of my projects examines how our solar system formed, through the lens of magnetic fields; magnetic fields are thought to be the key for the formation of planetary systems. Measuring ancient magnetic fields that were recorded in very small inclusions located in some meteorites is helping us to understand this relationship.
I plan on pursuing this line of research further as a career, studying the connection between planetary formation, habitability, and magnetism.
What was the Earth like during the evolution of the first animals? My research in the Bergmann Lab to answer this question helps us understand how and why animals evolved on Earth. It may also help elucidate what conditions could lead to the emergence of complex life elsewhere in the universe.
I focus on Earth's surface environments about 550 million years ago. At this time, early animals lived in the oceans. The sedimentary rocks deposited in these ancient seas—like limestone, sandstones, and shales—record both physical and chemical information about the environments in which they formed. The global carbon cycle, erosion and weathering, and climate all had a role to play in shaping early animal habitats—and the rocks I study record evidence of these forces. I use field and laboratory techniques to test hypotheses about their role in shaping animal habitats. I also use radioactive isotopes within my samples to date events in the rock record. These dates are useful for understanding the relationship between animal evolution and other key changes in erosion and perturbations in the carbon cycle.
My efforts to understand the world of early animals has taken me to five continents, eight countries, the Arctic Circle, and many collaborators' labs. Unraveling this exciting story has required aerial drones and state-of-the-art mass spectrometers, as well as hiking boots and battered field notebooks, and I'm looking forward to where the adventure takes me next.
When most people think of fossils, they imagine the lithified bones of an ancient organism in a museum display. However, the fossils that I study from around Death Valley are drastically different; they are casts and molds of soft-bodied organisms, with no modern analog, which existed near the end of the Precambrian Era, about 542 million years ago. Soft-bodied preservation is rare within the fossil record, but is prevalent in this time period globally.
My work in taphonomy, the study of fossilization, is centered around understanding the biogeochemical processes controlling the preservation of these soft-bodied organisms. Specifically, I am interested in the interactions between microbes—which can act to both decay the organism and produce minerals which help preserve it—and clay minerals, which can shield soft tissue from microbial decay. What makes these fossils especially interesting is how well the structure of the organism is retained, even with a low abundance of replacive minerals produced by microbial processes. Scientists have proposed many hypotheses, such as the presence of microbial mats, to explain how this fossilization process occurs; however, experiments using soft-bodied marine organisms to elucidate the processes are lacking.
My research with Tanja Bosak is filling this gap by conducting informed taphonomy experiments analyzing the decay of scallops' flesh in the presence or absence of clay minerals, which we see within the fossils, and cyanobacteria (the microbes that predominated at the end of the Precambrian). These experiments help to tease apart the roles that the microbes and minerals play in the biogeochemical processes that occur during the initial decay of the organism, and help us to understand which conditions are conducive to preservation. By understanding these processes, we can better interpret the features within the fossils. This will allow for us to know more about these organisms which lived right before the Cambrian explosion.
State-of-the-art global climate models (GCMs) disagree on how tropical rainfall will change with climate change, especially the pattern of changes. Consequently, we look to simpler models as tools for understanding the underlying mechanisms.
Studying with Paul O'Gorman, my dissertation is focused on the dynamics of precipitation in the tropics. As the addition of greenhouse gases warms the atmosphere, the amount of water vapor (specific humidity) in the air increases. What effect does this additional water vapor have on rainfall over tropical oceans? Does rainfall over tropical oceans go up at the same rate as water vapor? Previous authors used simple models to learn that, on average, tropical rainfall does not increase as much as water vapor because the large-scale circulation of the atmosphere changes, too. The combined effects of changes in water vapor and the changes in the circulation contribute to complicated changes in rainfall which are very hard for state-of-the-art climate models (GCMs) to simulate.
Through the use of simple models, we are learning that the circulation changes are important for the pattern of rainfall changes over tropical oceans, but a source of disagreement in GCMs. Further, we are learning that these circulation changes are largely tied to horizontal gradients in temperature at lower levels of the tropical atmosphere. This work is very exciting because it contributes to understanding the complicated and nuanced ways that the climate responds to greenhouse gases, and why climate models sometimes disagree on aspects of these responses.
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