Site 1: Cahokia Mounds State Historical Site
on the
St. Louis Sundial Trail
The
Cahokia Mounds State Historical Site is located in Collinsville, IL,
about 8 miles from St. Louis, MO. It is designated by the United
Nations as a World Heritage Site. Numerous earthen mounds
contain the remains of an ancient city that was occupied by Mississippian
Indians from 700 to 1400 AD. Archeological excavations have
revealed where a large solar calendar once stood. Because it was
made of wood, the solar calendar is now called Woodhenge.
The Woodhenge
has been recreated by erecting representations of tree trunks at the
locations where the excavations have revealed wooden markers had been
placed by the original occupants. Alignments of the markers
indicate important solar events, such as the solstices and equinoxes.
There are four concentric circular rings of markers, respectively having
24, 36, 48, and 60 markers, and there is a fifth partial ring with
markers along Eastern sunrise locations.
More can be learned about the Cahokia Mounds State Historical site by
navigating to the website
http://www.cahokiamounds.com/cahokia.html/. Dr. Michael W.
Friedlander, of the Washington University Department of Physics,
participated in the excavation of Woodhenge and the identification of
the astronomical significance of the location of the posts. His
paper, "The Cahokia Sun Circles," published in Vol. 88, pages
78-90, of The Wisconsin
Archeologist, in 2007 contains a detailed discussion of the geometry
of Woodhenge and the calculations he has made in demonstrating its
properties as a solar calendar.
To go to the next site on the St. Louis Sundial Trail, which is about
12.5 miles from Woodhenge, click on
Site 2, St. Louis University
Hospital, or to go to other sites on the trail, return to the
trail map.