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Woodhenge 72 Project

Beginning in the early part 1990s, the Woodhenge 72 project is the most recent UW-Milwaukee project to investigate Cahokia. Several factors influenced the development of the the Woodhenge 72 project. The first of these was the discovery of unique post-circle monuments at Cahokia by Warren Wittry in the 1960s. Wittry called these monuments "woodhenges," and proposed they operated as prehistoric observatories used to track the rising position of the sun on the eastern horizon at various times of the year. In order to test this idea, Wittry placed upright telephone poles in the woodhenge post pits he felt marked the position of the sun on the eastern horizon at its solstice and equinoxes. At sunrise on September 22, 1977, Wittry's hypothesis was provided support as the rising equinox sun rose over the first terrace of Monks Mound and aligned with the equinox post of the reconstructed woodhenge.

At about the same time that Wittry was conducting his woodhenge experiments, UW-Milwaukee researchers were concluding their detailed mapping of some of the smaller mounds at Cahokia. One of these mounds was a small, nondescript mound located to the southwest of Mound 72, now known as Mound 96. When Mound 96 was originally mapped in 1979, the mound appeared to be a small T-shaped mound with a ramp oriented to the east. Examining the relationship of Mound 96 with Mound 72, Fowler noticed that the smaller mound was located a distance of 125 meters from Post Pit 1 in Mound 72, the same distance as the diameter of Wittry's woodhenge.

Reexamining data from Mound 72, Fowler identified other features within the mound that might have been large post pits. Interpolating a complete circle using the 125 meter diameter, Fowler proposed that a second post circle monument may have been constructed at Cahokia, and had posts located within Mound 72 and Mound 96. To test these ideas, Fowler began the Woodhenge 72 Project.

The preliminary testing of Woodhenge 72 began with a soil conductivity survey of the predicted locations of post pits, followed by soil coring and limited test excavations. These investigations seemed to indicate that there were disturbances at certain of the projected post locations that warranted additional study. Large scale excavation of projected post localities began in 1992 with encouraging results until a heavy rain storm brought an abrupt end to the excavation efforts. Subsequent excavations in 1993 met with similar results, when the water table was hit in one of the units, slowly flooding it from below.


Cahokia Home Page

Metropolitan Cahokia
    Mapping Project
    Mound Analysis
    Air Photo Analysis
    Palisade Investigations
    Mound 72

Monks Mound Investigations
    First Terrace
    East Lobes

Other UWM Contributions
    Ramey Field
    Woodhenge 72
    Mound 96

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Last Updated: April 24, 2002
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