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Using GPS to Study ice and Geology in Antarctica

Carol Finn 

Carol's work as a geophysicist involves reading the magnetic data of Antarctic rocks that lie below the ice's surface. Carol takes signals of the data from a plane and then analyzes this data to study how the Earth's plates move, and how and why the West Antarctic Ice Sheet may be changing.

Why should kids know about Antarctica?

"It is an exotic place almost untouched by humans. I think there is something about that kind of contact with nature in Antarctica that is fundamentally so human. It's a place that is still wild enough that you can test yourself against it."

How can students everywhere be good stewards of our least known continent?

"Recycling is a huge way to make a difference. I recycle more since I've been to Antarctica. NSF recycles 99% of all materials used in Antarctica, which is way more than any other program that I know. I think the nearest anywhere back in the States is 40%. That really increases your awareness of what can be recycled. Also, I know that the building growth in the west, where I live, is horrible. Places like Antarctica that are so pristine make you appreciate untouched places and how valuable they are. It makes you realize that leaving unspoiled places is really important."

More on Carol Finn the Person 

Field of Study Geophysics–uses rock data to investigate the stability of the West Antarctic Ice Sheet

Hometown Montclair, New Jersey

Thoughts on Middle/High School "Earth science just didn't appeal to me in school... now I use it every day, so you never know!"

Interests in Middle/High School "Started out with a rock collection, ended up with boys, the Beatles and being outside."

Interests Today Skiing, karate, mountain biking, rafting, hiking, golf

Life Lessons from the Field "In the field people are... totally focused on real issues, so there's no time for politeness... I've learned to take criticism in the right spirit and not get too defensive when suggestions are offered–I've also learned that I can figure out almost anything if I need to."

Major Influences "When I was in college, at Wellesley, they had a lab requirement so I took geology. We would go to the beach or on other great field trips, and my interest in rocks continued. At the time I was planning to go to law school, but geology classes were so much fun that I just kept taking more of them. I loved being outside."

Number of Trips to Antarctica So far five

AMNH: What's so important about your field of study in Antarctica?

Carole: Antarctica is the last continental frontier–most of the rocks are buried under a cover of ice and are completely unknown. I'm investigating the geologic formations under the ice in Victoria Land, Antarctica, to find out about the way Australia and Antarctica once fit together. This work is important because it can offer clues about early Earth climates and what may have influenced climate change in the past. Knowing how the continents fit together earlier in Earth's history may help us figure out the nature of the geology hidden by the ice. I'm also investigating how the West Antarctic Ice Sheet (WAIS) may be changing. Why does it move and under what conditions, and what influences its speed? We want to know why the ice sheets are moving so that we can better predict whether, and why, the WAIS is retreating or breaking up–and what will happen if it does. We hope to determine if the West Antarctic Ice Sheet is thinning, or if it's in balance with its environment. Predicting changes in the ice sheet is important: if it were to thin and break apart, sea level all over the globe could rise by about six meters.

AMNH: How do you look for answers?

Carole: I work in the Transantarctic mountains and near Byrd Station, using equipment that is carried in airplanes. These airplanes fly over study regions on the Antarctic ice sheet. The main piece of equipment is called a magnetometer, which detects the magnetic properties of the rocks under the ice sheet. My job is to interpret these magnetic data to determine the composition and structure of the rocks, what's in them and how they fit together. This field of study is called Aeromagnetics. In Victoria Land, we are looking at rocks that are 500 million years old; and very few are exposed at the surface. Remember, 97% of Antarctica is covered by ice, which makes investigating the rocks of Antarctica very challenging! The work is based on the theory of plate tectonics.

AMNH: What are plate tetonics?

Carole: This theory says that the Earth's crust is made up of a series of plates. These plates are constantly moving over each other and sliding by each other and spreading apart from each other. According to the theory, this movement has been going on for billions of years; at different points in history, the continents have been closer together, and at others, they've been farther apart. We are trying to reconstruct old "mega continents" that existed around 800 and 500 million years ago. They are called Rodinia and Gondwana. Australia and Antarctica were connected at these times. I'm working to see if we can figure out how these two continents fit together using the magnetic information in certain rock types found in both areas. Our discoveries can help us figure out what Earth's climate was like in the past–and what might have influenced that climate. Our work on the West Antarctic Ice Sheet also requires that we study the magnetic data of the material under the ice sheet. Usually it's hard rock or water or till–a mixture of different sizes of particles carried by the ice sheet. The magnetic data can tell me something about the type of rock that's under the ice sheet. For example, if the till is soft, it generally means that it has a lot of water in it. If we discover that the till is soft, we next need to find out where the water comes from. And if there was a lot of water, we know that there was a heat source–you need something to melt that ice! I look for magnetic evidence of a heat source, such as the magnetic signal given by volcanic rocks. If we can link faster moving ice sheets to areas with high heat flow, we know a little more about why the ice sheets are moving.

AMNH: What exactly are you looking for when you're looking at "magnetic data"?

Carole: We can figure out where the rocks came from by looking at the magnetic signal. The strength of the magnetic signal tells you about the number of magnetic minerals in the rocks; you might be familiar with that concept when you see a magnet. A big magnet exerts a lot of pull because it has a lot of magnetic material in it. Magnetic minerals usually have a lot of iron in them. Volcanic rocks contain more iron minerals, so if we see a stronger magnetic signal, we know we may be looking at volcanic rocks. Volcanic rocks are often located near a heat source called a magma source. That's where very hot rock, molten rock, approaches the surface of the Earth. Sedimentary rocks contain fewer iron minerals, so they have a weak magnetic signal. When I combine our magnetic data with my knowledge of geology, I can figure out a lot about the composition of the rocks.

AMNH: The signals tell you about the origin of rocks beneath the ice; how do you find out about plate motion using the magnetic data?

Carole: I look at plate motion by looking at the patterns on magnetic maps. These look like topographic maps, showing cones, valleys, and their amplitude and shapes. A big hill or cone means strong magnetism; that tells us something about the type of rock there. I can match up the patterns of rock type and magnetic signal.

AMNH: How do you collect and analyze the magnetic data of rocks below the ice surface. Aren't you up in a plane?

Carole: Remember, we're not actually collecting the rocks; we're using a magnetometer to measure the magnetic signals of the rocks down there. The magnetometer can be attached to the plane's wings, but we usually hang it on a cable from the bottom of the plane in a six-foot-long container that looks like a rocket. We call the container the bird. The magnetometer is a little tiny instrument that detects total magnetic field. I don't need to know the total magnetic field, just the magnetic signal of that sample, so I correct that result by subtracting the general Earth's magnetic field. That leftover field is the magnetic signal given by the geology, or the rocks in that area of the Earth's crust. The magnetometer readings are located using GPS data. Together, we obtain a data set that tells us the magnetic reading at a particular latitude, longitude, and elevation. This allows us to make maps of magnetic data.

AMNH: Do you mean you could'nt do this kind of research before GPS?

Carole: Before GPS, scientists did this kind of research with aerial photographs, and matched the features they recorded with ones in the photos to figure out where they were. But it was tough in Antarctica, because there aren't many features visible in aerial photographs, just lots of snow and ice, snow and ice. Therefore, the positions were not very accurate and only general magnetic maps could be made.

AMNH: With all that flying, you need to stay on top of the weather forecast?

Carole: Predicting the weather is definitely tricky in Antarctica. Most weather forecasts came from McMurdo, where the weather could be quite different than the remote camps from which we worked. Because the weather conditions can change so rapidly, there are always people on weather watches in camp while flights are out. If bad weather approaches a camp, and it looks like a flight won't be able to land, the weather watchers contact the plane. A few times, planes have had to land at other camps. But the pilots who fly us are very good.

AMNH: How much flying do you do during a typical work day in Antarctica?

Carole: When we're on the ice, the day might include flying for four to eight hours in a plane with lots of equipment. We cover a five-square-kilometer space, going back and forth to make a grid–with a total of 700 kilometers of lines! We collect magnetic data, gravity data, and information about ice thickness and surface elevation. Then we return to the camp, which is filled with lots of computers–and propane heaters!–and we spend lots of time analyzing and testing the data.

AMNH: Do things always run smoothly?

Carole: It's a lot easier for us than it was for the early explorers! We have engineers in the field, so often things can be fixed there, and we make sure to bring spare parts. But it's always important to be prepared. Sometimes we have software problems and our coworkers need to send patches from the States to fix the program. One time, I was joining the rest of the research team in Antarctica when they called me from the field to tell me we needed another GPS antenna. I had to drive to San Francisco, hunt down an antenna, drive back up, and catch my plane that afternoon. Another time our gravity meter broke. Someone had to fly back to the U.S. to find one and bring it back. But the experience of working in remote places in bad weather with limited grant money teaches you how to persevere. When equipment breaks or you run out of fuel, you can't let it get to you. You have to resolve the challenges any way you can and just keep going. When you're in the field dealing with hard science problems and your equipment breaks, you have to do whatever is necessary to fix it and get your data. This is getting back to perseverance, but I've also learned that I can figure out almost anything if I need to. It's also really important to learn how to deal with your colleagues. There can be plenty of arguments about the project because people have definite opinions about their work. You have to learn not to take things personally. In the field, people are blunt and honest and totally focused on real issues, so there's no time for politeness. My work in the field has taught me to take criticism in the right spirit and not get too defensive when suggestions are offered.

AMNH: WHat's your favorite area in Antarctica?

Carole: Going to the South Pole is very special. I've been there two times and there is no place like it on Earth. I think it is also a mental thing; the concept of being on the bottom of the world is pretty neat.

AMNH: What does the South Pole actually look like?

Carole: They're rebuilding the South Pole now, so I'm not sure if it's going to change, but it's really cool. There are cool flags surrounding the striped barber pole that's the symbolic location of the South Pole, and there's a big geodesic dome. The geologic South Pole moves every year, and the U.S. Geological Society comes down to survey and reposition it. The actual pole–the magnetic pole–doesn't move that much, but the ice that's over it does. That's why the stake needs to be repositioned on the ice.

AMNH: What other good memories do you have of Antarctica?

Carole: I remember seeing Adelie penguins on my first visit by ship. They were so funny. Each member of the penguin group was bowing to another group of penguins. I had just come from doing research in Japan and I couldn't believe what I was seeing–they seemed really to have human behaviors, bowing just as I had seen people doing in Japan. The penguins went on to be so funny, skimming along the ice on their stomachs and basically putting on a comedy show for us. The Emperor penguins were completely different, cool and beautiful. An unspoiled environment is wonderful and important. I believe that humans want to have contact with the environment. We need to leave open spaces. Antarctica is very special because it is the ultimate open space.

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