Paper No. 9-2
Presentation Time: 8:00 AM-12:00 PM
MORPHOLOGY OF STREAM SEDIMENTS IN UPPER CREEK, BLUE RIDGE MOUNTAINS NC
Fluvial terraces and other geomorphic formations reflect both the depositional and erosional history of a landscape in relation to the larger watershed. Portions of the Blue Ridge Mountains have a recent, but significant, history of high-impact land use and studying the resulting legacy effects can enable a more comprehensive understanding of sediment transportation and storage. Extensive logging initiated in the late 19th century in the southern Blue Ridge Mountains cleared the majority of the forests in the area. It is also known that catastrophic floods and landslides in 1916 and 1940 had a significant impact on the landscape and nearly wiped out nearby settlements along Wilson Creek. These events likely mobilized a large amount of fine-grained sediment through local watersheds, including Upper Creek’s main channel and its tributaries. In contrast, the nearby Linville Gorge was never deforested and recent work indicates that terraces within the Gorge date to the Mid to Late Holocene. The goal of this project was to understand how deforestation impacted valley bottom sedimentation in Upper Creek. Preliminary results, including mapping of all terraces along the river, indicate that formations along Upper Creek are characteristically different than those found along the Linville River. This suggests that Upper Creek experienced additional sediment deposition. Several terraces mapped along Upper Creek suggest a pulse of sediment was delivered to the lower reaches of the channel including some terraces that indicate a braided channel may be recently dominated the valley bottoms. The morphology of terraces and debris fans along Upper Creek indicate that the recent logging of the area impacted the morphology of the channel and its floodplains, although sediments have not been dated thus far and legacy sediments are difficult to differentiate from natural mass wasting debris.