GULLIES, ALLUVIUM, AND SOIL: A SWIFT GEOMORPHIC RESPONSE TO EARLY AGRICULTURE IN THE NORTH CAROLINA PIEDMONT

Gullies are common geomorphic features in the Piedmont of North and South Carolina and are typically attributed to early agriculture. However, the precise cause and timing of erosion has not been addressed, leading to a lack of understanding of the processes that produce incised hillslopes in the region. We examined 74 forested, stabilized gullies in ~ 5 km² of preserved land north of Charlotte, North Carolina. Sixty-eight of the 74 gullies either contained alluvial fill or had alluvial fans at their mouths. Soil pits were dug on 17 of the alluvial surfaces and soil profiles were described. Seven charcoal fragments were sampled from soil profiles for radiocarbon analysis. Radiocarbon ages display peak age probabilities in late 1700s, coinciding with early Euromerican settlers and predating the period of highest agricultural intensity. Soil development and stratigraphic relationships support this interpretation of early gully formation. These results suggest that settlers had an immediate impact on the land – likely as a result of deforestation and the initial period of agriculture. This rapid landscape response reinforces previous work suggesting that the argillic soils of the Piedmont are unusually prone to erosion during to changes in land use. Understanding the inherent erodibility of Piedmont soils is important as a new wave of deforestation occurs in the region associated with suburbanization.