For many people, the earthen mounds of eastern North America are nothing like the architectural wonders of Europe and Asia. Compared to the Parthenon in Athens or Hagia Sophia in Istanbul, Ohio's Newark Earthworks and Fort Ancient might seem like piles of dirt. However, new research is revealing surprising sophistication in the form and structure of ancient American earthen architecture.
     Archaeologists Sarah Sherwood of Dickinson College and Tristram Kidder of Washington University reveal the complexity of earthworks from Poverty Point in Louisiana to the Cahokia Mounds in Illinois in their paper 'Da Vincis of Dirt,' published in the latest Journal of Anthropological Archaeology.
     "Mound building required a planned effort that incorporated site preparation, sophisticated understanding of soil properties and considerable engineering skills." Sherwood and Kidder argue that ancient American Indian mound builders were highly selective in their choice of dirt and had "a comprehensive knowledge of the structure and availability of local geological materials."
     At Newark's Great Circle, for example, dark brown earth from the uppermost soil layers forms the outer portion of the circle, while bright yellow-brown earth from deep beneath the surface forms the inner portion. Earthworks also might show evidence of thoughtful engineering using a variety of techniques, such as mixing different types of soil together to create a stronger material for mound building and cutting and stacking blocks of sod to help stabilize the steep slope of an embankment.
     The different soil colors at the Great Circle likely conveyed important symbolic information. Moreover, Newark's Octagon Earthworks are aligned to the rising and setting of the moon over an 18.6-year cycle, which also suggests a spiritual component to the architecture. The fact that these ancient Americans chose earth as their medium of expression should in no way detract from their amazing achievements.

Edited from The Columbus Dispatch (1 May 2011)