Explorations
Secrets of Ancient Iceland
Dispatch 2: Connect the dots
"If I knew what was in there, I wouldn't have to dig a hole."
My first day with a trowel and shovel, digging toward the Viking Age in a hayfield in northern Iceland, this offhand remark by John Steinberg became my motto.
Steinberg, from UCLA's Cotsen Institute, is hoping to make digging outdated for survey archaeology—and it looks like he might get his wish. He is working with Penn State anthropologist Paul Durrenberger to see the pattern in which this valley was settled; the settlement pattern will help them determine when and why Iceland was transformed from a collection of Viking chiefdoms into part of the kingdom of Norway sometime between 870 and 1262. But to find the pattern efficiently, they need a way to locate and measure all the Viking houses without digging lots of holes.
"There are two reasons for not digging holes," explains Durrenberger. "When you dig a hole, you destroy the site. And when you dig a hole it costs lots of money."
Volunteer Suzan Erem holds the stadia rod, the target that the Total Station uses to measure the coordinates of a point, while Northwestern graduate student Doug Bolender records the information on a survey form. Photo by John Steinberg
For two weeks, Steinberg and UCLA geophysicist Brian Damiata have been taking pictures down through the grass and soil of this hayfield using a remote sensing device called Ground Penetrating Radar (GPR). GPR acts like a microwave camera, sending electromagnetic waves into the earth and picking up the echoes or reflections. They've processed the GPR data into a series of colorful animations showing what the field would look like if a giant took a trowel and peeled off slices horizontally, centimeter by centimeter.
Steinberg concedes that you do need some imagination to connect the dots left by the microwave reflections into the outline of a house. To learn how to read the GPR images better, the next step is to compare them to what traditional trowel-and-shovel archaeology can say about the site. So one night the sod was lifted off a 750-square-meter section of the hayfield, down to the bottom of the plow zone, and the next morning seven of us were issued shovels.
The Vikings in Iceland didn't build houses of stone or wood: The walls we're looking for are made of blocks of turf—essentially the top of a peat bog—often layed up in a herringbone pattern. For two days we scraped the site, using our shovels like spatulas to lift off an inch or two of dirt at a time, looking for the turf signature. Turf is denser and has a higher organic content than dirt. It is swirled with soft earthen colors: greenish-gray and brown, orange and gold, black and rust-red. Both the texture and the color should help us see the walls. But first we had to clean off the layer of white tephra deposited during an eruption of Mount Hekla in 1104. It was unmistakeable: When I hit it, my shovel would glide like it was greased and the upper strata of soil would just flake off.
When the delicate trowel work began, I was assigned a spot covered by ash from a peat fire. Based on the parts we could see, the west wall of the house should continue underneath the ash. I was to define its edges, looking for where the turf blocks broke off. It wasn't easy to see.
The edge of the excavated part of the peat ash pit, showing the colorful strata that formed as ash was dumped into the hole over a period of years. Photo by Doug Bolender
Peat ash is almost as slippery as volcanic tephra, and it comes in very distinct colors, from pale pink to cranberry, with bright yellow, orange, black, and white mixed in, all in all a good match for the palette the Norwegian painter Edvard Munch used in his famous work "The Scream." Working at it for eight days (the ash was much deeper and wider spread than expected), I became quite fond of the color scheme. All week it was sunny and breezy, the smell of cow manure mixing with that of fresh-cut hay, and the days blended together as I scraped and dug. On my coffee breaks, I would look out across the valley, surprised to see the mountains bright green in the sun, or shaded gray with cloud, or sometimes just as pink as the ash I was so focused on.
Somebody, it seemed, had been dumping peat ash into a pit dug against the outside wall for years after the house was no longer being lived in. The ash had blown over the wall and filled in the crevices between the tumbled blocks of wall and roof inside the house: One section, once cleaned off, looked like a relief map, showing each individual turf block. The house had already completely collapsed before the white tephra from the 1104 eruption covered it.
Another day, as I was concentrating on distinguishing pale pink ash from greenish-gray turf, scraping carefully with my trowel, Doug Bolender, a graduate student at Northwestern University, walked over, looked down, and said, "Nancy found the edge of a wall." When I leaned back and readjusted my gaze, it just popped out: A section of wall about a foot long was left rising above the pit out of which I had cleaned the ash. Right under my hand was a completely straight edge.
Parts of the north and south walls of the house turned out to not be so easy to define, and something very funny was going on with the east wall. To clear up these ambiguous spots, Steinberg and Damiata brought a computer out to the site and tried to align what we'd found with the GPR images. Damiata had been working on the GPR data for a week, adjusting the color scheme and tinkering with how the computer transformed the data into images to highlight different types of reflections. One solution made the walls, which are weak reflectors at their bases, much more clear in the pictures. Another highlighted the floors, which are strong reflectors, Damiata says, probably because they're very compacted, greasy, and gritty with ground-in charcoal. Other strong reflectors are stones and the jumbled bones and trash in the rubbish heap, or midden.
On the eastern wall, what seemed to the trowel-and-shovel crew to be an entrance lined up rather well with a set of strong, deep reflections that Steinberg interpreted as cobblestones at floor level. Just down the hill, we had uncovered a pile of bones marking the top of the midden. Said Steinberg, pointing from the dirt at his feet to the computer image and back, "If that turns out to be the entrance, and this turns out to be pavement, and there's the midden, well, that's pretty perfect."
Rita Shepard working away at the bottom of a meter deep test pit. Photo by John Schoenfelder
If it turns out to be perfect, says Durrenberger, "then that means the GPR has accurately told us what's in the dirt. And that's the point of the exercise. Then we can explore other sites without digging holes."
And digging holes is what Durrenberger has spent the last two weeks doing, while I was scraping up pink peat ash. At the first hole, he says, "we hit the white 1104 tephra layer and, as Doug predicted, there was evidence of people living there before that. So then I got assigned a new site to dig another hole in. I'm down 1.8 meters, digging through turf, and I haven't found the 1104 yet."
Check back in two weeks for the final dispatch from Iceland, as the Glaumbaer dig wraps up and the research team reflects on what they have found.
Nancy Marie Brown is a former editor of Research/Penn State. Her current book, "Voyage of a Viking Woman," is about a woman who explored Greenland and Atlantic Canada and lived in the house currently being excavated at Glaumbaer a thousand years ago.
