Natural and human-induced prehistoric and historical soil erosion and landscape development in Southwestern Tennessee, USA


Eastern North America has seen widespread soil erosion in recent centuries. While the impact of soil erosion and feedbacks to the environment have been recognized for the period of European settlement, the period of prehistoric cultivation by Native Americans and its effect on soil erosion are largely unexplored. At the Dogwood gully system, a 820,000 m2 watershed located along the Chickasaw Bluff in southwestern Tennessee, extensive geoarchaeological investigations, which include historical data, have enabled a detailed examination of soil erosion history. The results yield insight into the relative influence on soil erosion of human activities (both prehistoric and historical) versus natural geomorphodynamic processes controlled by climate and neotectonics. Three relatively short phases of geomorphic activity occurred throughout the Holocene. In the mid-Holocene climate changes caused a change or decline in the protecting vegetation cover which triggered fires, runoff, and soil erosion. The influence of Archaic and early Woodland peoples on the landscape has remained elusive. The loss of at least 12 cm of topsoil during the Mississippi period (∼900-1400 CE) may have influenced land abandonment in the 14th century. After the introduction of European agricultural techniques, a similar amount of soil was eroded but within a period of only 80 years. In the 1930s the area was reforested but runoff and gullying are still active on bare surfaces. The research shows that the impact of prehistoric land use patterns on the geomorphic system was likely generally much more important than previous studies has suggested.

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