Today at Brown

LAKE MYVATN [August 31, 2008] — It was a steep climb, but we reached the top of Hverfjall, a lopsided bowl-shaped remnant of an eruption that predated Jesus. We sat down, pausing to catch our breath and to take in the view.

We looked out over a mosaic of blackened dunes, small caldera with concentric rings of yellowish vegetation, mounds of reddish and black dirt and jagged cracks that resembled sutures crisscrossing the landscape. At the horizon stood two giant smoking geothermal vents and a conical mountain that touched the clouds.

We looked out over an area that straddles the mid-Atlantic ridge, an active volcanic zone. It is fissure central, where the ground, heated from below like some giant furnace, has ripped itself open repeatedly, at times oozing lava over land and water, at other times blowing rocks and fine matter for miles around. This hot, fuming, scarred terrain speaks to the raw, violent power of nature, and its ability to fundamentally alter and re-alter all that is within its reach.

In Hverfjall’s barren “Marscape,” a tulip-like flower blossoms. The Brown University geologists had come to the Krafla Volcanic System to learn more about how volcanoes have changed the surface, how the minerals were formed or altered during these events, and how other influences such as water and glaciers further shuffled the chemistry and mineralogy of the landscape and what lies below.

We had plenty to work with this day. Hverfjall, for example, is a tuff cone – a ring of volcanic rock formed about 2,500 years ago when magma combined with water spilled over the Earth’s surface. The cone, charcoal black throughout, rises up to 450 feet and has a diameter of nearly 3,300 feet. In other words, it is immense, providing panoramic views that enthrall hikers and scientists alike. While violent, it was what you could call a long, slow eruption, unlike the sudden, brief (relatively speaking) eruptions like Mount St. Helens in 1980.

As Jack described it, eruptions like Hverfjall generate more “oozy” lava that spreads over the land, while eruptions like Mount St. Helens send plumes of ash into the stratosphere, as the mountain literally blows its top. The two do share some commonalities: Hverfjall blew out fine matter, and Mount St. Helens generated lava flows. But they are fundamentally different, created under different circumstances, and both are of interest to geologists.

The Brown team descended into Hverfjall to learn more. The slope was laden with ankle-high black soil made up of tiny, rounded pebbles. There were spotty clumps of yellow flowers with mini tulip-shaped bulbs topped with crown-like spikes, and some patches of long-blade grass. Other than those small bursts of life, Hverfjall was barren.

Mike and Ulyana took a core sample on the tuff cone’s floor, while Jack and Bethany collected rock specimens. The group clambered back to the ridge to take in the view and moved into the valley below.

The volcano’s tuff cone rises 150 meters and is 1,000 meters in diameter. Mike and Ulyana took another core sample along Hverfjall’s outer slope to compare with the sample taken in the interior. As they worked, Jack and Bethany moved on to observe reddish patches within a small zone of vegetation. They determined it to be nothing more than a sulfide deposit.

In a cut in the canyon, the group came across fine dirt that was a burnt orange. This is a spot, according to literature from a volcanism conference that Mike and Ulyana had attended a week earlier in Reykjavik, where tephra, or blasted volcanic fragments, fell in such huge amounts that they bent trees to the ground. The ash was then oxidized, creating the burnt orange hue.

Mike and Ulyana decided to take a core sample. As they pulled the 50-centimeter plug out of the ground, the very bottom showed reddish, black and tan soil, with odd white flecks.

“This might be the weirdest sample yet,” Jack said.

Fascinated, the group took a syringe sample of the overflow from the bottom of the core and bagged the rest.

The day before, we had seen a wholly different terrain. On this outing, we drove from the Dreki campsite to the Vatnajokull glacier, which covers 8 percent of the country and is the largest in Europe. Along the way, the Brown scientists spied a dried riverbed with black banks and tan geometric patterns in the channel that looked like scales on a fish.

This area is part of the interglacial lava shield, formed some time after the last glacial episode some 20,000 years ago. The deposits, the group reasoned, probably came from the glacier – material ground up as the glacier advanced, then retreated. The rocks had been further modified by runoff from the glacier. When this happens, the coarse, heavier rocks are deposited first, closer to the glacier, while the lighter, finer materials are transported further away. The rocks, even tiny ones, are rounded, a shape created through their constant tumbling as they are carried by the current.

The Brown geologists were interested in further understanding these processes and their effect on the mineralogy because there is growing evidence — led in part by Brown scientists Jim Head, Jay Dickson, Jack, and others — that Mars once had glaciers. If glaciers did exist, they may have been part of a system including lakes containing sediments, and sediments are seen as great places for life to exist. That doesn’t mean that the conditions for life ever existed on Mars, but it does help make a compelling case.

After a few hours of driving, stopping, and sampling, we reached the glacier. The ice pack was an amalgamation of serrated peaks, colored dark by dirt that had settled on top. In some places, the dirt on the glacier was thick enough to slide on, and Ulyana took full advantage, launching herself down a slope. At the bottom, a charged current flowed from under the ice. The main channel cut a defined swath as it twisted and turned over the land. All around it, nearly as far as we could see, were smaller, more constricted bands called braided river channels, so named because they routinely cross over each other. Together, the river trunk and its braided branches were repeating an act thousands of years old, one that may continue for thousand of years to come.