Cultural phases defined for Emergent Mississippian and Mississippian periods in the American Bottom.

Fowler, M. L., 1996. Introduction. In The Ancient Skies and Sky Watchers of Cahokia: woodhenges, Eclipses, and Cahokian Cosmology. Wisconsin Archaeologist. 77(3/4):3-11. Fig. 1.6, p.10

Image courtesy of The Wisconsin Archaeologist.