The summer I joined them, Doug and his colleague John Steinberg, both now at the University of Massachusetts-Boston, were testing a new protocol that has since proved to be a very powerful way to locate ancient structures buried beneath the soil--without having to dig. Their method centered on a ground-penetrating radar (GPR) device: a sealed plastic box full of electronics, which sent pulses of microwaves into the ground and picked up their echoes; these were then read by sophisticated computer algorithms and compiled into detailed maps of the density and other characteristics of the earth at certain depths. The archaeologists spent weeks dragging the GPR box over the ground above a suspected Viking Age house. My contribution was to hold one end of a 100-meter tape measure so they would walk in a straight line.
|John Steinberg and team doing GPR in Iceland in 2005.|
Following a mental grid Doug had set over the field using GPS, we took a sample every 50 meters (165 feet) along a certain north-south line, then turned east and took another line. For each core, we chose a place between þúfur—the knee-high grassy hummocks caused by frost-heaving. Þúfur is one of the first Icelandic words you learn out on the farms. They make walking through an Icelandic pasture an obstacle course, taxing the ankles and straining the knees. Once I misstepped, my attention caught by a pretty palomino stallion in the next field, and fell full-length on top of a þúfa—it was like a belly-flop onto a medicine ball.
|Archaeologist Doug Bolender working in Iceland in 2015.|
The core was beautiful. “You could make upholstery out of that one,” Doug said.
|A sample soil core from the SCASS blog.|
|Tephra line in a turf wall in Iceland.|
Using this handy vulcanological dating method, if you take enough soil samples (and for his Ph.D. dissertation on medieval farming practices, Doug collected approximately 16,000), you can see a “massive jump” in phosphorous levels, due to animal manure, in farmers’ fields between 870 and 1100. You can also, if your grid is tight enough, find and date the farmers’ houses and garbage middens by the position in the soil cores of charcoal, bone, peat ash, or chunks of turf.
It's not an easy job to get 16,000 soil cores. There are surprising dangers.
One day, two members of our team, Susan and Tara, were coring in a fenced field. The farmer had told them it contained a herd of “calves.” One came over and pissed on the leather corer bag. The next day, it came up to them and let them scratch its nose. It stood beside them, grazing, while they recorded the last soil core.
|Skagafjörður, Iceland, where we were coring.|
Up ahead Tara saw a drainage ditch—This way!—she leaped into the ditch and sank up to her thighs in muck. Susan followed. The bull tried to get under the fence and into the ditch. He went under head and shoulders. They dropped the corers on the bank and slogged up the ditch away from him until they could get up the bank and under the far fence. Leaping up the bank out of the ditch, Tara cradled the $300 GPS monitor, Susan the soil-coring data sheet. They waited until the bull lost interest and went away before going back into the ditch to retrieve the rest of their equipment.
Watch the PBS special "Vikings Unearthed" online here: http://www.pbs.org/wgbh/nova/ancient/vikings-unearthed.html. For more on my book The Far Traveler, see my website at: https://www.nasw.org/users/nmb/books.html#FT. For more on Doug Bolender's work at UMass-Boston, see the blog of the Skagafjörður Church and Settlement Survey here: http://blogs.umb.edu/scass/2016/04/02/doug-bolender-stars-on-vikings-unearthed/.