This finding illustrates both the ambition and the limitations of the Cahokia builders.

They constructed a monument of extraordinary scale without the engineering knowledge of soil mechanics that would have allowed them to predict and prevent the settlement and slumping that occurred over time.

The mound’s western instability was not a design flaw in the conventional sense — it was an unanticipated consequence of the specific soil conditions beneath the construction site.

The builders could not have known, without the geological and engineering science that would not be developed for centuries, exactly what was happening in the soil beneath their monument.

The fact that the mound has survived at all — that nearly a thousand years of settling, slumping, rainfall, erosion, and agricultural encroachment have not reduced it to a feature indistinguishable from the surrounding landscape — is itself a testament to the scale of the original construction.