On three bluffs high above Lake Michigan in Waukegan, Ill., an archaeologist has found places where Indians fashioned tools from stones, perhaps more than 3,000 years ago.
What makes the finding potentially significant is that the highlands, cut through by ravines, have never been disturbed by plows or other farming implements, said archaeologist Rochelle Lurie.
"We can make a preliminary evaluation that these sites are important because they are undisturbed," she said. Any cultural materials -- remains of structures, stone tools, preserved food -- would be in the same spot where they were some three millenniums ago.
Most archaeological sites in northern Illinois are on land that has been plowed and the artifacts have been moved around or damaged, she said.
These bluffs may contain cultural materials that would help 20th-century Americans learn about people who lived here thousands of years ago, she said. That is much longer than most Indian relics can be traced.
Because of the difficult terrain of the site, which is on the north edge of Waukegan, Ms. Lurie does not believe it was a major settlement. But it may have been a campsite.
In a survey for Drobnick Realty, which owns the land, she found stone chips that are the byproduct of making sharpened tools like spear points and arrowheads, she said. Her broad examination of the land last November, however, found no intact stone tools.
Ms. Lurie also did not find any indications of burial mounds.
A report that Ms. Lurie prepared for Drobnick was sent to the Illinois Historic Preservation Agency, which will evaluate her findings and possibly recommend that the developer pay for additional archaeological studies.
Tom Wolforth, an archaeologist with the agency, said that the "significance of this case is not the grandeur of the site but that there are so few undisturbed sites" in the Chicago area.
"We're pretty excited," he said.
If the Drobnick site is found to contain important materials, theagency will try to urge the developer to preserve them by not disturbing the area.
The agency could also seek to excavate the area and remove what it finds for preservation, he said.
It does not have the power to block development, Mr. Wolforth said.
The state agency was alerted to the possibility that the land might contain Indian materials by a woman who found a sharpened stone tool in the spring of 1989 when she dug a hole on the property to transplant a raspberry bush.
The agency, which is responsible for evaluating and caring for historical sites, notified Jay Drobnick. He hired Lurie, who operates Midwest Archaeological Research Service in Harvard, Ill., to examine the 31 acres.
"I want to find out what's there," said Mr. Drobnick, who grew up in Waukegan and still lives there. His firm plans to build about 50 homes on the site but so far has not sought any permits.
Mr. Drobnick and his landscape architect, Glenn Christensen, believe that the tract is one of the last pieces of undeveloped land on the North Shore.
In her survey, Ms. Lurie's workers dug holes 1 1/2 feet deep every 50 feet or so and sifted the unearthed material through sieves.
"We were left with lots of chipping debris and fragments," she said.
"The only way to explore the site is to excavate systematically," said Ms. Lurie, who holds a doctorate in archaeology from Northwestern University.
But her work so far has been cursory and only further excavation, if recommended, will provide clues about the people who once made tools there.
The chipped stones and other man-made debris cannot be dated. Ms. Lurie estimated the site was used more than 3,000 years ago because no pottery was unearthed. Indians began making containers from fired clay about 3,000 years ago, she said. If pottery is found in later studies, Ms. Lurie is prepared to revise her estimate of the date.