IOWA CITY - A 7,000-year-old archaeological site in Des Moines is so well-preserved and complete that it will provide researchers with exciting insight into the types of tools the people in the village used, the types of animals they kept and ate and the types of seeds they planted, University of Iowa archaeologists said Thursday after the find was announced.

The site, nicknamed "the Palace" because of its size and preservation, yielded the remains of two humans, a woman and an infant, that are the oldest human bones to be found in the state.

"It's always fun to find the oldest of something ... but the real significance lies in how well-preserved it is," State Archaeologist John Doershuk said. "This site is important because it was intensively occupied and very quickly river floods sealed the deposits and very quickly preserved items that otherwise could have been lost. It's all about preservation context, and that's what this site really has in abundance that other sites don't."

Because so many items were found together at the site - UI archaeologists gathered more than 6,000 artifacts - it helps researchers put into context the information they learn about how the villagers lived, what they ate and how they were developing as a people, Doershuk said.

"It's all the archaeological questions that anthropologists wish they could answer in more detail but often can't," he said.

Construction work was ongoing at the site, the future home of a new wastewater treatment facility north of the Des Moines River in southeast Des Moines, when workers moving dirt noted charcoal and burned earth stains, Doershuk said. The Office of the State Archaeologist, based at the UI, was called to the site in December 2010 to monitor the work and investigate interesting findings. The site is owned by the Des Moines Metropolitan Wastewater Reclamation Authority, made up of 16 metro area municipalities, counties and sewer districts.

Anytime a project has federal permitting or federal funding, like this one does, it triggers certain requirements, including archaeological studies, Doershuk said.

"They realized, essentially, there was much more there than previously had been thought," he said.

The UI archaeologists worked through May to collect as much information and as many artifacts as possible before construction work had to return to that portion of the site. They found the remnants of four oval-shaped deposits, possibly houses, as large as 800 square feet with hearths.

"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," Bill Whittaker, a project archaeologist who co-directed the dig, said in a UI statement Thursday.

The burial pit was discovered in March, about six or seven feet below the ground surface. Items were found in the grave along with the remains, including a spear point. The remains were handled in accordance with burial protection laws after they were studied.

"We were looking for more village-types of deposits, hearths and storage pits," Doershuk said. "Fortunately the crew working that day had enough experience with what human bone looks like that they recognized it right off."

The age of the site was determined by radiocarbon dating based on wood charcoal from the burial feature and also the spear point found there, by matching it to the time frame of other similar artifacts found in the Midwest, Doershuk said.

The crew also used laser technology to map more than 12,000 archaeological data points so they can develop 3-D models of the site with computer software.

"The field work is done, but it's just getting going in the lab," Doershuk said. "We have at least a year's worth of analysis and writing and comparative work."

While construction on the wastewater treatment plant at the site continues, there is adjacent, un-excavated land that researchers believe will yield more archaeological finds, and they are working on a preservation plan.