It’s Friday afternoon, and geology professor Alan Chapman is crouched in the corner of his office, tinkering with a gravimeter, which measures minute changes in the earth’s gravitational field.  By testing it out in Olin-Rice and around the state, his Geophysics students will see complex formulas in action. We asked Chapman what he hopes students take away from his courses, how he brings his own research into the classroom, and why leading a class is not unlike playing a guitar for a crowd.

How did you get into geology?

For a lot of people, geology isn’t on their radar until someone or something alters their trajectory. For me, it was taking an introduction to geology class as an undergrad at the University of Minnesota. At the time, I knew I wanted to study science, and I was majoring in astronomy, but something wasn’t clicking. I was having a great time in this intro course, and I talked to an advisor and told him I have this hard decision to make between astronomy and geology. He said, “It sounds like an easy decision to me.”

I found my niche in an area of geology that attempts to understand mountains: how mountains form in the first place, what processes happen along the edges of continents. As you go farther west, the area gets all crunched up. I try to understand those faults, folds, and volcanoes—and their role in shaping the continental crust.

What do you love about teaching?

Before my teaching career, I enjoyed playing music. Teaching is not unlike when you’re up in front of a crowd playing the guitar. You can tell whether the audience is into it, bobbing their heads—and you can tell if something’s off about your delivery or sound and you need to adjust. I get the same vibes from students as I got from a crowd. It’s not like standing up and giving a speech and feeling like it doesn’t matter whether the audience is along for the ride. I like the mixture of preparing and observing. If I’m teaching a class on gravity and everyone’s going to show up and not ask any questions, it wouldn’t be as fun. I prepare in advance, I learn a lot in advance, and that’s exciting. Communicating that material is exciting, and so is the improvisational piece.

How has your teaching style evolved?

I started out doing PowerPoint-based lectures. And for a lot of people, that “sage on a stage” approach works. I also know a lot of folks who like to completely flip the classroom and have it be totally student-focused. At some point, I started incorporating more active learning techniques. I found a mix that seems to work for me. There’s certainly a place for delivering some material, chewing on this big chunk of knowledge that I’m putting out there, and then reconvening and applying it.

What are your classes like, and where does the gravimeter come in?

Geophysics is a very quantitative class, Mondays are mostly lectures with a small activity: we’ll talk about a formula and then manipulate a data set.

On Wednesdays I like to do a longer activity. For example, we’ll use the gravimeter to take a measurement on each floor of Olin-Rice. Gravity falls off not just with the distance to the center of the earth, but the distance squared, and the gravimeter is so precise that it can measure perceivable differences 10 feet up from the ground floor. Gravity is different on the third floor of Olin-Rice than the first floor! It’s all geared toward a better understanding of the formula we’ve talked about on Monday.

On Fridays, we do a Paper of the Week. For example, we’re talking about a paper on gravity in the state of Minnesota. There’s something in Minnesota called the Midcontinent Rift, where 1.1 billion years ago, the middle of the continent tried to split apart. All along this fault, there’s a big pile of basaltic rock where the continent almost turned into an oceanic basin like the Atlantic Ocean. It’s called a failed rift. The hope is, at some point during the semester, to go from one side of the rift to the other with the gravimeter to see the fault underneath us.

What kind of assignments do your students like best?

In my Structural Geology and Tectonics classes, it’s Rock of the Week. I bring a rock in a box and provide a map showing where it’s from, and the students’ job is to describe the rock using a series of questions. That part is free of interpretation. The second part involves thinking about the processes behind the rock. A sandstone might have little ripples on top, which probably means it was at the bottom of some old river, so you can say something about what way the water was flowing when the rock was hardening. Those assignments are some of their favorites.

What do you hope students learn from your class?

After an introductory-level class, I hope the takeaway is that we have this fragile earth and we should respect it. We approach that from many angles: the water underneath us in aquifers, climate, energy, erosion. We think about the earth as a system that can be tinkered with—and we need to make sure we’re not tinkering with it too much.

In upper-level classes, there are big concepts about processes that occur deep within the earth, like how the earth gives off its heat through convection cells in the mantle. But then there are also marketable skills to be acquired that they can mention in interviews. They can say, “I’ve used a magnetometer and a gravimeter,” or in instructional geology, “I know how to draw a geologic cross-section.” Those skills can be used if you’re trying to figure out where an aquifer runs or if you’re interested in exploring for ore minerals.

What are Mac students like in the classroom?

I’ve taught at institutions where I’ve had a much harder time getting class discussions off the ground. With Macalester students, there’s an enthusiasm—if everyone doesn’t share it at the beginning of class, they’re going to share it by the end. That’s infectious. They’re very intelligent and very excitable, and as a result, some component of what I do involves turning the teaching over to them.

How does that happen?

I like to do field trips. Last semester, my Tectonics students and I went to Michigan’s Upper Peninsula to look at rocks from the Midcontinent Rift. I organize most of my field trips by handing out some field guides to my students in advance, and then they become the experts. Each student is responsible for one field trip stop. I tell them before the field trip, “Look, as soon as we get in the van, I’m a chauffeur. I’ll be sitting here with a pastry and some coffee, and I’m no longer the expert. You’re the expert.” We walk up to an outcrop, and they can tell us about what’s going on there. I wouldn’t feel as confident about doing that at other institutions. And it gives them a sense of ownership about the field trip.

How does your research inform your teaching?

The most “Wow, that’s amazing” moments in class happen when I talk about some aspect of my research. That’s not necessarily because my research is particularly exciting, but because I’m particularly excited about it. I put a spin on it that you wouldn’t be able to get out of a book. I bring rocks to class from my personal research, as well as data sets that I’ve gathered from those rocks. I’ve calculated ages from that rock by extracting tiny minerals. There’s a whole suite of information available to students by looking at a rock and knowing the ages, and that’s a quick way for students to envision the entire scientific process and method. Seeing the scientific method laid out as an active piece of study is an eye-opener.

What are you working on now?

My most active project right now focuses on rocks that we find blasted to the surface of volcanos. We find them in Arizona, but we don’t expect to find them there. We find similar rocks in central California. Since there isn’t a volcanic arc in Arizona to which we can attribute this, the idea is that something like an oceanic plateau collided with the edge of the continent and bulldozed material that was at the base of the crust eastward into Arizona. We test rocks from Arizona and California: are they the same age? If so, when we crush them up, are they chemically similar? I have three Mac students working on this project.

What do you like to do for fun?

I like to play with my kids. I have a six-year-old and a three-year-old, and they’re at fun stages of their lives. The other day I was driving with my six-year-old, and we’re on first-name basis somehow. He said to me, “Alan, I was just curious what people that study volcanos are called.” I said, “Those are called volcanologists,” and he said, “I want to be a volcanologist.” I tried not to react too positively and yell, “Yes!” But I felt a bit proud in that moment.

January 10 2018

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