IDENTIFICATION AND GEOMORPHOMETRIC ASSESSMENT OF STREAM TERRACES ALONG THE NORTH AND SOUTH FORK OF THE NEW RIVER, BLUE RIDGE PHYSIOGRAPHIC PROVINCE

Stream terraces are important landforms because they represent past periods of landscape stability, particularly in response to changes in climate and land use. In addition, terraces are potential locations of well-preserved archaeological sites because they occur near natural resources and above the active floodplain. However, these landforms are not commonly preserved in the Appalachian region due to high relief, narrow valleys, and active erosional processes, making their identification difficult. In response to this situation, we have developed a model for identifying the location of stream terraces in the Blue Ridge physiographic province. Initially, a grouping of four stream terraces in pasture were documented through the use of shallow geophysical surveys in an area of approximately 0.5 km² in the Jefferson 7.5’ quadrangle, immediately upstream of the confluence of Roan Creek and the South Fork New River. The model for extracting the location of these stream terraces was derived from the geomorphometric analysis of this study area. Initially, a 5 meter DEM was derived from LiDAR data collected through the NC Flood Mapping Program. From the DEM, the slope of the study area was derived and a 5 x 8 rectangular window was applied using nearest neighbor focal statistics in ArcMap 10.0. As a result at least one additional terrace, covered in hardwood forest, was identified in our study area. In addition, the characteristics of these terraces are further analyzed through remote sensing and GIS analysis. One characteristic of particular importance is the height of each terrace above the modern river level, which has been used to roughly estimate age in other studies. The terraces in our study area are between 2 and 46 m above the modern river level. Other assessed characteristics are the occurrence and area of younger versus older terraces as well as whether or not terraces are paired across a valley. This model is applied to the North and South Fork of the New River in North Carolina to map and assess the distribution and elevations of other terraces.