A Piece of the Mantle


Traversing the cliffs and craters of Iceland — tiny nation, monster volcanic hotspot — has long been compared to stepping foot on another planet.

Or at least the moon: In 1965 and 1967, a group of 25 American astronauts semi-secretly rehearsed what would be the first lunar landing in the Icelandic outback.

Indeed, Greenland’s slightly balmier neighbor is out of this world. Iceland is essentially a floating slab of volcanic rock — dark, jagged, rolling rock — pushed up from the bottom of the ocean, studded by geysers, gurgling mud pots and sky-blue pockets of steaming water. In its capitol of Reykjavik, which contains two-thirds of the country’s population — a mere 200,000 people — the stench of sulfur tumbles from every faucet, and underground pipes of hot-spring water run beneath each doorstep to melt the snow that falls there. In summer, the sun sets for barely four hours; in winter, the sky sleeps in an almost eternal night.

But Scripps Institution of Oceanography geochemist David Hilton finds Iceland to be anything but otherworldly. According to Hilton, the island is formed by an up-rush of underwater lava — what he calls a “geothermic plume,” shot from the Earth’s deep mantle layer — making it the closest thing we have to a piece of primordial Earth.

Ever since he based his doctoral thesis on Icelandic findings in the early ’80s, Hilton has returned over a dozen times to the remote island to collect additional samples of its ancient gasses. Still, he said, the Icelandic landscape never fails to amaze him.

“It’s rugged; it’s mountainous; you have these fantastic glaciers,” he said. “You have deserts — vast plains where there’s very little vegetation, just rocks. You have other parts of Iceland where there’s massive rivers coming from the glaciers; so it’s varied, it’s rugged.”

Hilton and a team of graduate students — including Scripps superstars Evelyn Füri and Peter Barry — made their three most recent trips to Iceland in 2006, 2007 and 2008, running on two $200,000 grants from the National Science Foundation. Despite the economic downturn, Hilton said he’s actually seen a boost in funding for research projects like his own.

“When Obama came in, he had the stimulus package, so actually a lot more money went into the National Science Foundation,” Hilton said. “So, [the economic crisis] has had the opposite effect there actually … There’s more funds out there to go and get, to do science.”

With the help of local land experts, the team collected as much as 200 pounds in samples per trip. They extracted water from fumaroles — gassy holes in the Earth’s surface — and hammered off pieces of rock and glass from the island’s crust, which would later release trapped gasses when crushed in the lab.

According to Hilton, when hot lava hits seawater, it freezes almost instantly inside a shell of glass. Because the particular volcanoes that formed Iceland erupted beneath glaciers, their magma froze especially quickly — creating ideal glass samples for tests such as Hilton’s, packed tight with gasses frozen in their original states. Compared to more common, superficial “subduction” volcanoes, which end up recycling their own elements as one plate of land slides under the other, Iceland’s 130-plus volcanoes are spewing material from up to 2,900 kilometers down.

In this way, Hilton said Iceland’s trapped volcanic gasses could teach us about the conditions of early Earth. When compared to meteorite samples, they could reveal similarities between our planet’s deep mantle and the primordial composition of the solar system. Or, when compared to modern volcanic material, they could demonstrate the changes Earth’s atmosphere has undergone since then.

“If you adopt a holistic approach, you want everything,” he said. “You want the deep stuff in Iceland, and you want the shallow stuff in the subduction zones. And in fact, that’s what I do. Any kind of volcano, I’m interested in.”

Indeed, Hilton seems to have a soft spot for all things volcanic. Originally from England, the Scripps researcher and professor is the friendly library type, with British teeth and the kind of voice that could score him a gig in Discovery Channel narration; the kind of soothing, all-knowing forefather voice that makes even the most eye-crossing geographical jargon a thing of fascination. In Hilton’s travel photos — sticking a tube into a pile of mud or grinning his windbreaker off in front of a volcano — he radiates the simple glamour of a man and his science.

“What tourists do is go out and about to see the scenery, which is what we’re doing anyway — but with a purpose,” he said.

On last year’s final trip north, Hilton rounded up one particularly pure Icelandic sample: Sæmundur Halldórsson, a University of Iceland graduate student.

“[Halldórsson] has been out and about in Iceland so much, that he virtually knows every hill, and every valley, and every lava flow,” Hilton said. “And he can tell you the difference between this lava flow and that lava flow — it’s fantastic.”

Halldórsson, a classically rosy-cheeked, towheaded islander, followed the famed geochemist back to Scripps with wife and music student Berglind Maria Tómasdóttir in tow — who likewise transferred her studies to the UCSD music department. They are new parents to a two-month-old baby girl named Anna Signy, and plan to see their doctorates through for four or five years before returning to Iceland.

Tómasdóttir, who is a contemporary flutist, described Iceland’s intimate, “vibrant” music scene as “basically a group of people that play in all the different bands.”

In describing the folks back home, both Icelanders agreed that the island’s natural environment has a lot to do with the way the population is shaped.

“Geographically, there’s a lot of energy,” Tómasdóttir said. “And they believe they can do almost everything.”

“But it’s like a balloon of air,” Halldórsson said.

“Not really,” continued Tómasdóttir. “But sometimes it would be better to be a little more organized. But the energy is there.”

Kind of ironic, Halldórsson admitted, leaving behind studies in geography at the University of Iceland (under the wing of professor Karl Gronvold, who Hilton first met back in 1983, and who participated in the team’s recent field work) to coop himself up in the Scripps lab with small pieces of his home country. But Halldórsson said Hilton has also encouraged him to work with samples from other volcanic areas around the world.

“Hilton really wants me to think about something other than Iceland,” he said.

The graduate student won’t run out of material anytime soon; Hilton takes a dizzying amount of fieldtrips to keep the sample supply on overflow. His most recent expedition was to Eastern Turkey — where he collected samples from a fault similar to the San Andreas Fault here in California — but he’s also been to Africa, Japan, China, Indonesia, Hawaii and sites all over Latin America in the last few years alone.

Halldórsson noted that he would never have ended up at Scripps if it hadn’t been for his hotspot hometown.

“We start to learn geology when we’re 13 or 14,” he said. “The reason I’m interested in earth science is because I grew up in Iceland.”

Much has changed in Iceland since Hilton’s wide-eyed expedition in 1983, when he said he was surprised to find the country had no pubs — a.k.a. no beer — and no TV on Thursdays. However, Halldórsson said he’s seen a definite Western shift in what was once a more quiet, isolated lifestyle.

“Iceland is fairly Americanized, actually,” Halldórsson said. “So we have all these fast-food chains and rubbish all around us.”

But there have also been many advances in research equipment over the last couple decades, including the technology needed to measure the isotope ratio in nitrogen — a large motivating factor for the most recent leg of the Iceland project. In order to extract the nitrogen from the Iceland samples, graduate student Barry first had to learn how to construct a nitrogen extraction line.

Thing is, the only other place on Earth where anyone was interested in such a contraption was the University of Tokyo. So Barry flew overseas for a crash course, then brought that knowledge back to Scripps, where it took him a year to re-create the line, at which point — much to the delight of his partners in noble-gas geochemistry — the nitrogen isotopes were finally ready to be measured by the mass spectrometer.

“We’re chained to our mass spectrometers,” Halldórsson said.

After working with Hilton for over five years in the field of noble-gas geochemistry, graduate student Füri has released the first draft of her doctoral dissertation: four separate reports on research she’s done in Monterey Bay, Costa Rica, the Central Indian Ridge and — of course — Iceland.

“What’s striking when you get there, is there are almost no trees,” Füri said. “And of course, for a geologist, that’s amazing, because it’s all lava — all rock.”

She said that gas samples from subaerial Iceland were more difficult to analyze than those from the other three underwater locations included in her dissertation, because much of the lava ended up being de-gassed, or contaminated by air.

“We don’t want [the samples] to be weathered or eroded — we want them to be quite fresh — but they can still be several million years old,” Füri said.

In the end, however, the team collected and tested enough original deep-mantle material to confirm and advance previous, more piecemeal research showing that volcanic material in Iceland is indeed very similar to the Earth’s primordial composition, and that its gasses can even be compared to solar wind.

“I mean, it’s kind of the question of, why do we care?” Füri said. “But Earth is so unique. I just think it’s important that we know more about the planet we live on.”

Readers can contact Simone Wilson at [email protected].

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