Thoughts on Theses: Fiona Anstey

In this week's Thoughts on Theses, Adela Thompson Page ’26 interviews Fiona Anstey ’24, a senior double majoring in math and geology. Her paleoclimate thesis requires extensive fieldwork and unexpected adventures.

Thoughts on Theses: Fiona Anstey
Anstey’s thesis involves fieldwork, where she looks at faraway rocks. Photo courtesy of Fiona Anstey ’24.

Q: I’m really excited to hear about your thesis. Would you first tell me a little bit about yourself?

A: Yes! I’m Fiona. I’m a senior, I’m a math and geology double major. And let’s see, I was born in Washington, D.C., but I grew up for most of my life in Tokyo. My mom’s side of the family is from Spain, my dad’s American, so I usually say I’m from a mix of those places. And I am also on the crew team. This semester I’m trying out coxswaining, which is really fun.

Q: Will you give me a general overview of your thesis?

A: Yeah, so my thesis is a paleoclimate thesis. So I’m looking at reconstructing the climate of the past and learning about ocean chemistry of the past. And I'm looking at the specific time in the late Silurian, which is about 400-ish million years ago. And if you look at the carbon isotope record, there’s a big anomaly that happened there. It’s the biggest in the Phanerozoic Eon, so [the biggest in] in a very long period of time. And this spike in the carbon cycle is also associated with a big extinction event of marine biota. So a lot of scientists are trying to figure out why that happened, and how the two events are associated. I’m looking at stable carbon and oxygen isotopes in turbidites. They’re limestones from the Inyo Mountains in California, which is close to the border of Nevada ... I’m reconstructing the paleoenvironment and looking at the ocean chemistry because some people think that there was widespread anoxia during that time, which is partly why so many marine creatures died. But there’s some debate about that.

Q: That is fascinating. You and Sarah [Leibovitz ’24] and Breanda [Gomez ’24] went to do field work with Dave [Jones, professor of geology] last summer, right? Was that for your thesis?

A: Sure did! That was my first real fieldwork experience — like proper fieldwork experience. We went last summer with Dave, and it was an adventure. It really was. We flew into Las Vegas, and the cheapest hotels in Las Vegas are the casino hotels.

Q: Is that where you stayed?

A: Yeah, we stayed two nights in a casino hotel, and it was like nothing I’d ever seen before.

Q: You, Sarah [Leibovitz ’24], Breanda [Gomez ’24], and Dave in a casino hotel?

A: Yes ma’am. It was insane. The best part was, because we stayed [in the hotel] one night before we went to the field and then one night after. And it was hilarious walking into the hotel, checking in, and all of us hadn’t showered in a week.

Q: And you’re in Vegas.

A: We’re in Vegas. We’ve got our massive packs with our rock samples, dirt, and sunscreen, and sweat layered on our skin. And everyone else is dressed to the nines, you know, ready for parties and everything. It was so weird.

Q: That’s really funny.

A: Yeah. So then we drove — Dave did all the driving — which was amazing, we listened to a lot of music. We went out [in the field], met one of his grad school friends, and he lent us his truck. And then we continued going off into the Inyo Mountains. And then we were there for five days. We set up camp; there was no running water. And we would go up to the outcrop every day to take samples and measurements. It was a really cool experience. I loved it.

Q: Did you weigh all the samples at any point to know how much you brought home?

A: Well, so one of the surprising things that I’ve learned from my thesis is that you can send anything in the mail.

Q: Oh, you mailed them?

A: We mailed them back from the Las Vegas post office, and they only took two days. Two business days. I don’t remember how much they weighed in total but there were four heavy boxes.

Q: I’m glad you shipped them; I was picturing you guys carrying them all in your suitcases.

A: Well, another thing I’ve learned from my thesis is that — especially with geochemistry — instruments break all the time. And you have to kind of work around that. So, one example was the mass spectrometer on campus just has not been working. This whole time.

Q: Oh no.

A: I ended up having to send my rock powders to [Professor of Earth, Environmental, and Planetary Sciences at Washington University] Dave Fike. And he processed samples for me. That was for the carbon and oxygen isotope values.

Q: Could you give a brief overview of what a mass spectrometer does?

A: Yeah, so to use a mass spectrometer, first you powder your rock, and then you put those powder samples into the mass spectrometer. It will dissolve it, and then in the volatiles that come out — the gas — it measures the ratios of the different isotopes of carbon in the carbon dioxide that’s released from the acidification.  

Q: Was it fun to smash the rocks in the lab?

A: It was a lot of fun. The smashing happened more in the field.

Q: Wait, intentionally or unintentionally?

A: Intentionally yeah, because you go to the outcrop and then you have to take a sample of the rock from where it is — entrenched in the ground. So you get your rock hammer and you hit the rock, but the thing is, you need to remember which way is facing up so you draw a little arrow on it. I like to draw the arrow before, some people hit the rock, break it off and remember, and then draw the arrow after. I don’t find that very reliable.

Q: So that’s why there are little arrows on our samples in the lab.

A: Yes, exactly. That tells you which way was up.

Q: I feel like that should’ve been obvious, but I didn’t picture geologists drawing on rocks in the field.

A: Oh, yeah, we’d use Sharpies, and the thing about limestone is it does something called karstic weathering, so it’s very spiky. And so every single Sharpie out there was bristly when we were done. When we came back to the lab over the summer, we made billets for thin sections for all 126 samples.

Q: Could you explain what a billet is?

A: Yes, a billet is a rectangle of rock that you cut using a rock saw, then from that rectangle you’re able to make a thin section, which is a 30-micrometer slab of the rock that you put on glass. And then you can use that to look at the mineralogy and microstructures of the rock using a petrographic microscope.

Q: And it’s beautiful.

A: And it’s so beautiful! Although some of my thin sections are not too beautiful, because they’re really fine-grained.

Q: Sed rocks are —

A: Sed rocks are more boring. Rachel’s rocks are so beautiful.

Q: It’s true.

A: Yeah. But some of them, like my favorite thin sections, are ones that show the basal scour of the bottom of the turbidite. And that’s where you have more fine-grained stuff underneath, and then the coarser-grained — in this case very fossiliferous — unit on top is eroding into the one below, and a couple of our thin sections capture that moment. So you can see the bottom of the turbidity flow as it’s eroding into the layer beneath.

Q: That’s so cool. So Sarah [Leibovitz ’24]  is also doing a thesis with Dave, are you working on similar projects?

A: Yes, our projects are complementary. I’m looking at the carbon and oxygen record, I actually just recently started working on a new elemental proxy of iodine and calcium, and it’s a proxy for anoxia. And then Sarah is doing sulfur isotopes. So we’re working on the same rocks, and we’re both working on reconstructing this paleoclimate and paleoenvironment story, but looking at different chemical aspects.

Q: So have you been able to collaborate with each other at all? Or at least commiserate?

A: Oh definitely. That’s a big part of it.

Q: How did you know you wanted to do a thesis with Dave?

A: The point when I realized I wanted to do a thesis with Dave was during my junior fall when I took his sedimentology and stratigraphy class, and I loved it. There was a big field component to that class — we would go pretty much every week to a different location. And we would use everything that we learned in class to reconstruct the story of what happened in that place, and I love doing that. It made me realize that what I love about geology is that puzzle of decoding what’s written in the rocks. And I knew that I wanted to keep doing that. And so I thought, okay, I should work with Dave.

Q: What have been the steepest learning curves in working on your thesis?

A: Well, time management for sure, especially because this semester I’m taking an extra class.

Q: What?

A: Yeah, thesis counts for two in the spring, but I’m taking three other classes, which has been a lot. And I applied to grad school last semester. So that’s almost as if I’m taking another class because of that, too. So it’s just been a work in progress still, learning how to balance all of those commitments.

Q: That makes me wonder about how you’re on the crew team, which is also a huge time commitment. How do you balance all those things?

A: I’ve always seen crew as an outlet for stress relief. Especially because there’s an outdoor component. I’ve always loved being in nature. It’s part of the reason I knew from the beginning that I wanted to be a geology major.

Q: You mentioned grad school, can you talk about your plans for that and maybe even plans beyond that?

A: I applied to grad school. I knew I wanted to do that because I loved my undergrad experience. And I loved getting to start to graduate from a user of knowledge to a creator of knowledge, with my research.

Q: I love that.

A: I think that it’s very empowering, having your own project and getting to explore your interests as they develop, and I’ve been able to do that with my thesis, and so I wanted to continue to do that in grad school.

Q: Do you want to continue researching a similar topic?

A: Yeah, I want to continue researching the paleoclimate. I am looking to do a project that in some way is connected to the modern climate. I think that paleoclimate is a really cool field because, A, there’s a lot of fieldwork involved and I love fieldwork, And B, there’s so much that we can learn from the past that directly impacts our understanding of modern climate and also the future trajectory of Earth’s climate. And I also like interacting with people, like I work at the Beneski [Museum of Natural History], it’s been one of the highlights of my college experience. I love working there, and sharing my science with other people has been a big part of that. I think that in grad school, you get to learn how to do that even more because you’re a TA in classes for undergrads, and I think teaching could be in my future. I also can envision myself working in a natural history museum, doing research. I think there’s a lot of opportunity.

Q: Do you have any advice for people who might want to do a thesis?

A: Start talking to professors early. Because if they see that you’re interested, and they know what your interests are, they’ll start mulling in their minds some projects for you. And I think the most important thing in the thesis is A, your interest in the topic, and B, your relationship with your thesis advisor.

Q: Can you tell me what it’s been like working with Dave as a thesis advisor?

A: I’ve enjoyed it so much. He’s so supportive. And just a wonderful, very knowledgeable adviser, a great scientist. I’ve learned a lot from him in the field, in the classroom, and in the lab as well. He’s always very supportive. I feel lucky that he is here at Amherst.

Q: Is there anything I didn’t ask you that you wish I had? Or anything I missed about what you’re involved in on campus?

A: Sometimes I even forget, let me think. I’m also the president of the Sustainable Ocean Alliance Club. That’s been a lot of fun and a big part of my Amherst experience, too.

Q: Do you have a TGIRx date yet? And will you say briefly what TGIRx is?

A: TGIRx stands for “Thank Goodness It’s Rocks.” If you know me, you know that I talk about it all the time. Everyone should come to TGIRx, and everyone should take a geology class and fall in love with geology, and turn into a geology major.

Q: At any point.

A: Even if you’re senior, you should still come to TGIRx. We meet every Friday and the whole geology faculty is there, and friends of the geology department are always welcome. There’s dessert and we talk about what projects we’re working on. I’m doing one with Claire [Jensen ’24] and Francisco [Reyes ’24] on April 12 about applying to grad school — tips and advice, and then I'm also doing one on April 26 about my thesis. Fridays at 1:30 p.m.