University of Iowa archaeologists have confirmed that an exceptionally well-preserved site, nearly 7,000 years old, contains what are among the oldest-known structures and human remains ever discovered in the state.
At the site, the UI-based Office of the State Archaeologist (OSA) found the remnants of four oval-shaped deposits, possibly houses, as large as 800 square feet and furnished with hearths. These structures were likely built of wooden poles sealed with clay. The field crew named the site “The Palace,” because of its size and preservation quality. Two partial skeletons were unexpectedly found at the site late in the project. The remains of a woman and an infant are the oldest human remains found to-date in the state by about 1,500 years.
“It became clear very quickly that the site was something spectacular—something none of us had seen before or probably will ever again, as well-preserved house deposits of this age are extremely rare west of the Mississippi River valley,” says Bill Whittaker, an OSA project archaeologist who codirected the dig with OSA general contracts program director Melody Pope.
OSA was contracted to excavate the site, found within the future location of a wastewater treatment facility in southeast Des Moines. The office routinely conducts such excavations on behalf of project applicants complying with state and federal laws.
A short documentary of the excavation can be viewed at www.youtube.com/watch?v=eB4KQuXTp_I.
The excavation took place from December 2010 to May 2011 south of Vandalia Road, north of the Des Moines River, and on the west edge of the existing wastewater treatment plant.
The crew collected more than 6,000 artifacts and used laser technology to map more than 12,000 archaeological data points, which will allow them to develop 3-D representations of the Palace site with computer modeling software.
“We don’t get many opportunities to see deeply buried, well-preserved sites of this size,” Pope says. “This discovery will provide important clues about what the living environment was like 7,000 years ago. It’s truly a treasure that will help us understand how the early people of Iowa made a living, what they ate, which technologies they had developed, and how they interacted as a community, especially their use of space and village organization.”
Archaeologists worked through winter, thawing the ground with heated blankets and keeping warm inside makeshift tents with propane heaters even as construction proceeded around them. By the end of May, OSA had completed excavation of the core of the site, which will be destroyed by construction of the $38 million wastewater facility slated to open in 2013.
In late March, as part of planned sampling near the southeast margin of the site, the crew unexpectedly discovered a grave 7 feet below the surface. Researchers haven’t determined the family relationship of the deceased, but preliminary analysis—including a radiocarbon date calculation based on wood charcoal from the burial feature—indicates that the individuals died 6,680 to 6,890 years ago.
The grave had been disturbed by erosion at some point after interment, long before modern construction activities began at the site. Systematic exploratory excavation of the surrounding area identified no additional burials.
Red ochre, a powdered mineral used by ancient cultures worldwide, was abundant, covering the remains. A spear point found beneath the woman’s lower back appears to have been intentionally placed there during burial. Also found in the grave were a small polished stone, a flint chip from stone tool making, and wood charcoal.
The OSA Burial Protection Program is legally responsible for investigating, preserving, and reinterring ancient human remains. Since Iowa’s burial protection law passed in 1976, the program has handled more than 2,000 projects in 98 of Iowa’s 99 counties. Removal and reburial of the human remains found at the Palace site is taking place in consultation with descendant American Indian peoples and members of the OSA Indian Advisory Council, and in accordance with state and federal laws.
State Archaeologist John Doershuk said it’s not possible to link the individuals to a specific American Indian tribe. Archaeologists do know that people living in that time period survived by hunting and gathering natural resources, rather than farming.
“The location, at the boundary of a large sandbar along the ancient Des Moines River, would have been appealing to people living the hunting-gathering lifeway,” he says. “It would have been a lush area, and we’ve discovered a broad spectrum of animal remains near the house areas: deer, raccoon, turkey, shellfish, bison, and lots of turtles. The river would have been a key route for transportation.”
A significant unexcavated portion of the Palace is adjacent to the construction zone, and state and federal officials are working with the Water Reclamation Authority to develop a long-term preservation plan for the intact areas. While the exact boundaries of the Palace site are unknown, archaeologists said there is evidence of both older and more recent prehistoric occupations than the 7,000-year-old structures; laboratory analyses of data from these deposits are ongoing.
Doershuk said while only two sets of human remains were located in the excavation, additional burials might exist within unexplored portions of the site. As additional details about the site emerge, OSA will produce a formal report, a web site gallery of images from the house areas, and educational publications and presentations to share with the public what they’ve learned.
For more information on the OSA, visit www.uiowa.edu/~osa.