the Devonian ended with a series of glaciations and extinction events, the early Mississippian saw the Earth in a greenhouse climate state with warm temperatures over much of the globe. Gondwana continued its northward drift and collision with Euramerica, building the Appalachian Mountains.
The Mississippian culture was a Native American civilization that flourished in what is now the Midwestern, Eastern, and Southeastern United States from approximately 800 CE to 1600 CE, varying regionally. It was known for building large, earthen platform mounds, and often other shaped mounds as well.The Mississippian is so named because rocks with this age are exposed in the Mississippi Valley. The Mississippian was a period of marine transgression in the Northern Hemisphere: the sea level was so high that only the Fennoscandian Shield and the Laurentian Shield were dry land.
