From urban dirt, ancient city emerges

Archaeologist Bill Iseminger pulls his jacket tight against the winter wind and sweeps his arm across the Illinois prairie. His finger traces the outline of a 40-acre grand plaza that was the Times Square of a distant American past.

A thousand years ago "this was the largest city in America north of Mexico," he says. "Between 10,000 and 20,000 people lived here" before the complex was abandoned under mysterious circumstances prior to 1400.

No towering monuments meet the eye. But with archaeologists now uncovering key parts of the Cahokia Mounds here, the dig has captured public interest as a window into America's heartland capital of the first millennium.

The excavation here amid a tangle of highways is part of a nationwide renaissance of urban archaeology, often driven by local development laws. And here, it promises to unearth a past that, though far removed from modern life, may hold lessons for today.

"The more I study their culture, the more I'm convinced they were just like us," says Brad Koldehoff, a University of Illinois archaeologist.

Although this main Cahokian site is a protected oasis eight miles east of St. Louis, the ancient metropolitan area sprawled in all directions, covering some 250 square miles of Mississippi flood plain. Archaeological work goes on in fits and starts throughout the former realm, now covered by a Gordian knot of freeways on its western edge and suburban sprawl elsewhere.

Recently, Mr. Koldehoff has been leading an archaeological dig mandated by law as a result of excavatory work on a new drainage system. Virtually in the shadow of the Gateway Arch across the Mississippi, his team sifts the ground under a riverboat gambling billboard.

But instead of hitting a jackpot of native American artifacts, he is finding mostly raw dirt.

To a layman, that would be bad news, but to Cahokian archaeologists, even soil speaks volumes. The Mississippians - the generic name given Indians that lived along the river but left no written record of their identity - not only moved earth to build mounds, they moved it to even out swales for table-flat plazas.

And that is precisely what Koldehoff and his team are seeing, confirming previous theories that a plaza covered the area a millennium ago. "It's surreal sometimes, being there alongside one of the busiest interstates in the country, your mind 1,000 years away," he says. "You uncover an old piece of ceramic pipe or a shirt, then you look up and see the skyscrapers of St. Louis across the river."

Compared with ancient Egypt or Incan and Mayan civilizations, where stone structures and carvings yield a plethora of clues about primitive ways, Cahokia yields its secrets grudgingly.

Cahokia relied on relatively fast-deteriorating wood for construction. That, combined with relatively wet weather conditions that destroy artifacts such as leather goods, makes the task of a Cahokia archaeologist as difficult as that of a detective trying to solve a homicide without a body, a motive, or a weapon.

What archaeologists do know about the Cahokians' demise is somewhat disturbing.

After an apparently vibrant growth period, a defensive stockade was built around the perimeter of the plaza. Separate archaeological efforts have uncovered evidence of murderous raids on communities in outlying areas.

As of now, there is no evidence that outside invaders threatened the Mississippians, nor is there direct evidence of internecine strife, but it is suspected.

As the decades progressed, the logs used for dwellings and rebuilding of the ramparts narrowed in diameter. Archaeologists suggest that this indicates widespread deforestation.

There may have been a snowball effect, in which deforestation led to loss of fuel and game and also silted streams, thereby lowering fish counts and causing flooding. How severe these problems were and whether they contributed to stress on the political system are unknown. The only thing archaeologists are sure of, based on current evidence, is that Cahokia appears to have faded away rather than ended abruptly in a natural disaster or human cataclysm.

However the Cahokian civilization ended, though, it survived for hundreds of years as a cosmopolitan and perhaps diverse culture. As such, historians say, it provides a valuable picture of a culture that has often been stereotyped as not-so-noble savages in film and fiction.

(c) Copyright 2000. The Christian Science Publishing Society