The Olsen lab visited the Cahokia Mounds State Historical Site this weekend, and it was a good opportunity for me to learn about a culture so often forgotten, yet so close to home. The Mississipian culture was one that thrived in North America; they used tools, practiced agriculture, and most notably, built mounds. The inhabitants of Cahokia would dig out basins for their houses to sit atop, which would provide a more favorable indoor climate in both summer and winter, and they would deposit this earth atop one of many mounds being constructed in the city. The largest, Monks Mound, was supposedly constructed over 300 years. This is no small feat for a people without horses or the wheel.
The location of Cahokia was superb for agriculture, and they grew previously wild North American crops such as sumpweed, goosefoot, knotweed, little barley, maygrass, sunflower, and squash. However, it is thought that the introduction of maize from Central America was what allowed the people of Cahokia to increase in population and create a vast and powerful city. A solar calendar, known as "woodhenge" comprised many large wood posts, set in a large circle; it was used to mark solar fluctuations and the start of winter and summer. This is a powerful component of agricultural societies, as planning for sowing and harvests with a calendar allows for more predictability and food security.
Unfortunately, by around 1400 CE, after years of decline, the city was abandoned, long before the arrival of Europeans. The reason for the decline is attributed to many factors, although one seems to make the most sense to me - deforestation. Cahokia required wood for burning in the winter, and for constructing buildings and walls. Without horses or the wheel, this means that those harvesting trees would have had to walk to this resource, but as they harvested more and more, the edge of the forest would have become more distant, and eventually out of reach. The largest problem now facing Cahokia (and similar archaeological sites), is the threat of development and neglect. One archaeological site, now forever lost, is that of "Mound city", which is located in present day St. Louis, the mounds of this site were used as fill in construction projects during the development of St. Louis in the 1800's.