FAYETTEVILLE, Ark. – X-ray vision is an attribute usually reserved for comic book heroes. But a University of Arkansas archeologist is using new technology to view prehistoric villages without even removing the soil that covers them.
Dr. Ken Kvamme, associate professor of anthropology, spent the summer just outside of Pierre, S.D., at the site of a prehistoric American Indian settlement called Whistling Elk. Though early American explorers like Lewis and Clark and George Catlin may have found hospitality in such a village, Kvamme was not so fortunate.
"The entire site of this village rests beneath about a meter of earth," said Kvamme. "Standing on the surface, there’s no evidence that a village exists at all."
For the past two years, the National Park Service has funded Kvamme’s Whistling Elk Sub-Surface Imaging Project to explore the potential for using remote sensing technology to create images of what lies beneath the soil.
This Saturday, Oct. 23, Kvamme and colleague Dr. Dennis Toom from the University of North Dakota will present their results at the Plains Anthropological Association Conference in Sioux Falls, S.D.
With a team of students from North Dakota, Kvamme and Toom applied four types of remote sensing technology to create four distinct images of the prehistoric village. These technologies included magnetometry, which reads magnetic fields in the soil; electrical resistivity, which injects a current into the ground, then records the soil’s resistance to this current; electromagnetic conductivity, which uses radio waves to measure how readily the soil conducts electricity; and ground-penetrating radar.
"Each method creates a slightly different image of the site. My goal was to combine these four images into a single image, where each technology is represented by a different color," said Kvamme. "The result was a color composite map that simultaneously showed all the information we had about the sub-surface archeological deposits."
The map revealed a village of 60-70 houses, surrounded by fortifications. Each house measured 5 meters across with a tunnel-like entrance and a central hearth. Carbon dating from the site indicates that the village dates back to 1300. And though archeologists refer to the original inhabitants as Initial Coalescent Villagers, Kvamme believes they were forebearers of the modern-day Arikara tribe.
Although remote sensing techniques created a clear picture of the Whistling Elk settlement, archeologists may not want to toss away their trowels just yet. Because the technology is so new, Kvamme’s team endeavored to test its accuracy by excavating portions of the village.
"We focused our excavation on the ‘Big House,’ which was twice as large as any other structure in the village," said Kvamme. "Before we began the dig, I placed a stake where our map showed the hearth to be and a stake at the edge of the walls. The stakes were dead on."
In addition to confirming the accuracy of the remote sensing maps, the archeologists discovered numerous artifacts that led to a better understanding of the village’s fate.
Because high temperatures can align the magnetic fields of iron molecules in clay, Kvamme’s magnetometry readings indicated that much of the village had been burned. This finding supported evidence from a limited excavation performed 20 years ago, which also suggested the village had been attacked. Items necessary for everyday life, such as tools, pottery and grain in storage bins, were found intact throughout two houses.
"These people left in a hurry," said Kvamme. "But our images suggest that they later returned and built a new village on the same site with a more closely-packed configuration."
This ability to view the layout of an archeological site before researchers remove the soil offers many advantages. The first such advantage is that it eliminates guesswork. Archeologists
can now be certain of digging in the right place. And because excavation requires vast amounts of money and manpower, remote sensing has proven itself highly cost effective.
In addition, remote sensing techniques enable archeologists to gather information in a non-invasive way. Some American Indian tribes resent the excavation of their ancestral grounds, said Kvamme, but electrical and magnetic imaging allows scientists to study sites without the possibility of damaging or disturbing them.
Finally, this technology could potentially save archeological sites from the ravages of progress – road construction, river dams and even agriculture have destroyed thousands of prehistoric sites throughout the country.
In fact, Kvamme’s team chose the Whistling Elk site because of its perilous location next to the shore of a Missouri River reservoir. Massive erosion had already destroyed portions of the settlement before government engineers stabilized the shoreline.
"The reservoir was built in the 1960s, long before any of our cultural preservation laws. They dammed the river because cities like St. Louis were being damaged by floods," said Kvamme. "Nevertheless, it’s a shame. Some of the best archeology in the country is being washed away."
Despite the advantages offered by remote sensing technology, Kvamme believes that it will never fully replace archeological excavation. Rather, he sees the two techniques working hand-in-hand.
Electrical, magnetic and radar readings offer images of large structures, but they cannot pick up minute details that may be buried and scattered throughout the site.
"You can’t see anything small with this technology – artifacts or human bones. But once you’ve identified a village, you know that artifacts will be found in the same location," said Kvamme. "Remote sensing is an excellent tool, but to learn the whole story, you still have to dig it out of the ground."
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