Julie Bowles is a University of Wisconsin-Milwaukee associate professor of geosciences. What you might not have guessed from that title is that she spends some of her research time studying volcanoes at the seafloor of the Pacific Ocean.
That’s where the Earth’s crust is broken up into a bunch of pieces that Bowles compares to “a jigsaw puzzle.” Those pieces move together, pushing into, over and under each other, making new crust from material deep under the crust—Earth’s mantle. And this is where new surface for our planet is made and why it’s important to study.
WUWM’s Jimmy Gutierrez talks to Bowles about her research and what these volcanoes look like so far underwater.
This conversation has been edited for length and clarity.
Julie Bowles: It looks like a linear mountain range that just extends for miles and miles and miles. It's maybe a couple of miles tall and has volcanoes at the top. You can't see very far in front of you because the light doesn't penetrate that deep in the ocean. So when you're right at the summit, it looks like a bunch of gray volcanic rocks that have some sediment piled up on top of them. Some of them look a little glassy.
There's often fissures, collapse pits. If you're really lucky, you might see a hydrothermal vent community. That’s when the cold ocean water gets down into the crust through the faults and cracks, and it heats up because of all the hot volcanic activity below. Then the water exits the seafloor [and looks] like a geyser.
That’s where you get these amazing biological communities that thrive around these vents.
Jimmy Gutierrez: Can tell us about the last time you visited the Pacific Rise and what you were looking for?
This last expedition was a collaboration with some colleagues at Scripps Institution of Oceanography. And some colleagues at Boise State University in Idaho. So, we all met up in San Diego and then we spent 11 days basically driving down to the South Pacific.
Once we got there, we were interested in looking at how often these eruptions happen, how big they are, are they clustered together in time, and if so, how are they clustered together in time? So in order to do that, we had to actually get samples from the seafloor, and we had to be able to see the seafloor as well to have an idea of what the seafloor actually looks like.
We had a couple of different specialized scientific vehicles that we were working with. One is called an autonomous underwater vehicle, and this particular one is named Sentry. So, Sentry is like a robot or a drone and it collects information about the shape of the seafloor—that gives us a high resolution picture of where there are small volcanic mounds, where there's faults, where there are fissures. It helps us to decide where we might want to go to collect samples and to look more closely.
Our target was the summit of this ridge. And ideally, we would want to collect actual rock samples and we would want to see with our eyes as well what's down there.
So there's a small submersible, like a little mini submarine that fits three people. There's a titanium sphere that the people sit in and that sphere was actually forged right here in Milwaukee, which is pretty cool. I got to sit in the Milwaukee sphere and go to the bottom of the ocean. And the submersible has these robotic arms that lets you collect samples that we could take back home and work with scientifically.
What we do is measure the magnetic properties of those samples and that tells us something—a little bit about how old they are. And it's kind of crazy when you think of the timescales involved. As a geologist, we talk about something that's a few hundred years or a few thousand years, like that's really young.
You're in the middle of the ocean doing this study for not a short amount of time. What did you see when you're out there that made the research more difficult?
We definitely ran into more challenges than we were expecting. It's really only safe to launch both of these vehicles when the waves aren't too chaotic or too big, and when the winds aren't too high. We definitely had a few days where there was a lot of movement on the ship [impeding this]. So we had tons of bad weather.
We finally ended up having a decent window of a few days towards the end of the cruise, where we could get maybe 3 or 4 dives in a row. But then unfortunately, there were two or three sharks in the area, which is not unheard of. The ship is sitting there for a long time. The lights attract kind of squid and smaller fish and then the sharks are attracted by those because they feed on them.
And at first the sharks were just kind of curious and they weren't really a concern. But towards the end, there were kind of more sharks coming, and they were starting to display more aggressive behavior. Curious sharks aren't really a problem for the swimmers, but sharks that are coming at you, it's a little bit more of a concern. So at that point, the decision was made to not put people in the water, no more dives. It's not worth risking anybody's life or health for this.
So you had this expedition to the summit, faced all these obstacles and challenges along the way. It also looks like you had an incredible pingpong tournament, too, based on the pictures. A lot of this work is very analytical and research-heavy, but do you ever find yourself inspired by the time that’s passed or what you’re seeing down there?
It's kind of crazy. I mean, people have certainly done work in this general area before, but the specific places that we went to and where we were able to dive down in the submersible, literally no person has ever laid their eyes on that spot on Earth before. And it's just kind of crazy to see this thing that is this eerie, otherworldly place that no one's seen before and very few people get the privilege of seeing.
For us in Milwaukee, we have Lake Michigan so close, which is great for study and access. Locally, I think we appreciate the smaller bodies of water in the state. But something we might not think about as much is how the oceans—these ginormous bodies of water, as you said, covering 70% of the Earth—affect us, including in our everyday lives with things like climate. What should we know more about the ocean?
Thinking of a couple different time scales; so if we're talking about the volcanic process and plate tectonics, this kind of overturning of Earth's mantle, that process over millions of years or hundreds of million years is part of the process that cycles carbon into and out of the atmosphere in between the deep Earth. So, over very long timescales, that's kind of helping to moderate our climate on Earth.
If you want to talk about shorter timescales, the water has a huge role on Earth's climate. So the water, whether it's in the ocean or whether it's in Lake Michigan water, actually can absorb a ton of heat without changing temperature. And compared to the land, the water can absorb a lot more heat. So it's this big heat pump and absorbs a lot of heat at the equator. Then the ocean currents redistribute that heat around the Earth.
If we didn't have the ocean currents, the temperature would probably be hotter at the equator, and it would be a lot colder at the poles. So it also has kind of a big moderating influence on our climate in addition to being a big carbon sink as well and affecting climate that way.
