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PRI's Environmental News Magazine

Exploring the Ocean's Geology

Air Date: Week of February 25, 2005

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Living on Earth host Steve Curwood talks with scientists at sea in the eastern Pacific Ocean. With the help of a submarine named Alvin and a robotic craft called Jason II, they're exploring an underwater canyon called Pito Deep and hope to uncover some of the mysteries of the ocean floor.

Transcript

CURWOOD: Our next guests are a couple of scientists who have hit bottom. The bottom of the sea, that is. In their research vessel the Atlantis, anchored just west of Easter Island in the Pacific Ocean, they are exploring Pito Deep, an underwater chasm, to get a glimpse into the geology beneath the ocean floor. The research submarine Alvin and a robotic called Jason II, allow a small crew to travel about two and a half miles beneath the ocean surface to go into Pito Deep and take pictures and collect samples of rocks and lava from the earth's crust.

Emily Klein is co-chief scientist of the expedition and a geology professor at Duke University. She joins us now from aboard the Atlantis.

Professor Klein, welcome to Living on Earth.

KLEIN: Thank you for having me.

CURWOOD: Now, what's a group of geologists doing out in the middle of the ocean?

Alvin is launched from the Atlantis. (Photo courtesy of Woods Hole Oceanographic Institution.)

KLEIN: Well, 70 percent of the earth's crust is covered by water and so a great deal of geologic interest on the earth takes place on the ocean bottom.

CURWOOD: You're out at this deep underwater chasm, described as an underwater Grand Canyon, called Pito Deep. What actually is Pito Deep?

KLEIN: Pito Deep is an unusual place in the ocean where, if you can imagine that, imagine the ocean crust being something like a layer cake. Normally, you can only see the top of the cake, that is to say, the icing, but we're particularly interested in looking deeper into that cake into the known layers of the igneous crust below the surface and normally you can't see that. But there are certain places in the ocean where due to some unusual tectonic forces, in this case, a large fault, a rift, has opened up a deep, wide chasm that allows us to look at the deeper layers of this cake or this ocean crust. And the Pito Deep is one such place.

CURWOOD: So, these places are found only in the ocean? There's no place on land that you can see this kind of formation?

KLEIN: There are rifting places on land, certainly. East African Rift is one of those places, but the ocean crust is unique. It's different from the continental crust, entirely different in chemical composition and in structure. And so, if we want to look and study the ocean crust we have to go to the oceans.

CURWOOD: Professor Klein, your research ship, the Atlantis, is using two types of vehicles to explore the ocean floor and in a few minutes we're gonna talk with a scientist in Alvin the submersible, but there's also Jason, a robotic. Tell me about the differences between the two, what they're used for, what they look like.

The Jason II uses its robotic arms to collect rocks from the ocean floor. (Photo courtesy of Duke University.)

KLEIN: Jason II is a vehicle that is, basically, an extremely sophisticated camera package with both video and still camera capabilities, as well as mechanical arms for sampling. It's tethered to the ship so that through the cable we get real-time video images and still camera images of what Jason is imaging. So, if you can imagine again with the Grand Canyon analogy, suppose the Grand Canyon were filled with water and it were utterly dark and you couldn't see the stratigraphy, the layers of rock on the side. You might drop a fancy camera down into the water and with its own propulsion system and guiding it, direct it to traverse the canyon wall, stopping to take measurements, stopping to use its mechanical arm to grab samples and put them in a basket on the vehicle to recover later.

Now, it's a magnificent piece of equipment, but it is a fairly two dimensional image that you get back of the ocean floor. So that capability, Jason II capability, in conjunction with Alvin, really brings the richness of the structures and the relationships of the geology on the ocean floor to life because with Alvin, then you can go in and with real observers, two scientists and a pilot, really look at the three dimensionality, go around cliffs, take measurements that you couldn't take with the two dimensionality of the Jason vehicle.

The Jason II takes photos of the ocean crust. (Photo courtesy of Duke University.)

CURWOOD: How about we go down beneath the surface and speak to the Alvin crew now?

KLEIN: That'd be great.

CURWOOD: Hello, is this chief scientist Jeff Karson? Over.

[NOISY BACKGROUND AMBIENCE]

KARSON: Yes, it is Steve. I can read you loud and clear down here on the sea floor. Over.

CURWOOD: Dr. Karson, who's down there with you in Alvin? Over.

KARSON: Down here today besides myself is Duke University graduate student Meagen Pollock, who is studying the volcanic rock here. And also, of course, we have a veteran pilot, Pat Hickey, who has made over 500 dives in Alvin over his career. Over.

The Alvin submersible, carrying a pilot and two scientists, begins its hour-long descent to the ocean bottom. (Photo courtesy of Duke University.)

CURWOOD: What does it feel like to be in a submarine so deep beneath the surface? Over.

KARSON: It's extremely exciting. I often say that it's like being in a space ship going to a different planet. We're very aware of the huge pressure of the weight of the ocean around us, but basically we're so excited by looking at the geology, that we don't even think about that. Over.

CURWOOD: What' s exciting about the geology? Over.

KARSON: Well, today we're moving up a huge cliff face. It's several hundred meters high. At the top of the cliff where we are right now, we're sampling some lava that was erupted on the sea floor about three million years ago. Earlier today, deep down on the cliff face, we were able to sample these tabular rock bodies called "dikes." These are, basically, the frozen conduits through which the magma once moved as it was erupted on the sea floor. We're also looking at a number of fault zones that are full of interesting minerals. Over.

CURWOOD: And before we go, what's the biggest surprise so far? Over.

KARSON: I think the biggest surprise for us is just how beautifully exposed the sea floor is here. It's just opened up for us in a way that we can study in great detail and really learn a lot about how the sea floor is made. And it's just a remarkable place and, you know, it's just the kind of place that if it were on land, would probably be some sort of national park. Over.

CURWOOD: Thank you so much for taking this time today. Over.

KARSON: Thank you. It's been fun. By for now. Over.

CURWOOD: Professor Klein, what happens next? What do you do with all the rocks that you're bringing up from the ocean floor?

KLEIN: My particular emphasis is on the geo-chemistry of the lavas and dikes that we will be sampling, we have sampled. And we'll bring them back to my laboratory at Duke University. We will grind them up, analyze their chemical composition, and from that we will determine their what we call petro-genesis, the origin of these lavas, how they relate to one another, what they can tell us about how crust is created at mid-ocean ridges.

CURWOOD: Professor Klein, do you ever go in Alvin?

KLEIN: Yes, I have dove in Alvin on two different cruises previously and I'm slated to go in the sub next week.

CURWOOD: What's your favorite part of the expedition?

KLEIN: Oh, my. I find the descent in the dark to be an overwhelming experience. We keep the lights off. We don't want to use battery power on the descent down so it's done in complete darkness. Sometimes we put on music and descend the two and a half miles to the bottom of the ocean. And then just as you get to the bottom of the ocean, the pilot begins to turn on the lights on the outside and, suddenly, you're in a magnificent world that nobody has ever seen before in this place.

CURWOOD: And what kind of music do you play?

KLEIN: Sometimes we play classical music, but on a recent dive we put on the soundtrack to "O Brother, Where Art Thou?"

[MUSIC: Norman Blake "I Am a Man of Constant Sorrow" Soundtrack- O Brother, Where Art Thou? (Mercury) 2000]

CURWOOD: Duke University geologist Emily Klein is co-chief scientist of the Pito Deep expedition. Thanks for taking this time with us today.

KLEIN: Thank you.

CURWOOD: We also spoke with her colleague Jeff Karson, who also teaches geology at Duke.

For photos of Alvin and Jason II, as well as some of the expedition discoveries, go to our website Living on Earth dot org. That's Living on Earth dot o-r-g. Just ahead, an endangered status debate for the biggest predator on land or ice.

Keep listening to Living on Earth.

ANNOUNCER: Support for NPR comes from NPR stations and the Argosy Foundation Contemporary Music Fund, supporting the creation, performance and recording of new music; the Kresge Foundation, building the capacity of nonprofit organizations through challenge grants since 1924. On the web at kresge.org; the Annenberg Fund for excellence in communications and education; and the W. K. Kellogg Foundation, from vision to innovative impact, 75 years of philanthropy. This is NPR, National Public Radio.

[MUSIC: Tony Furtado & Dirk Powell "Courtney's Promise" Tony Furtado & Dirk Powell (self titled) (Rounder) 1999]

 

Links

Pito Deep Expedition

 

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