USING RECENT, 3M LIDAR DATA FROM THE USGS NATIONAL MAP TO REMOTELY IDENTIFY LANDSLIDE FEATURES, REEVALUATE GEOLOGY, AND STUDY HISTORICAL GOLD MINING IN THE NE GA BLUE RIDGE MOUNTAINS

The USGS National Map recently released 3m pixel resolution, LiDAR-derived digital elevation model (DEM) panels that cover all of NE Georgia. Fifty two, 10x10km LiDAR DEM panels were downloaded from the National Map website, and these were used to create the following digital products: hillshade, color slope overlay, inverted slope overlay, and 5-foot contour elevations. A remote, ArcGIS platform computer-based LiDAR study was then initiated to identify possible landslide features, reevaluate previous geologic work in the area, and gain a better understanding of the genesis of gold deposits in the area. The SW end of the study area study area is near Dahlonega, GA, and extends ~75km NE to the NC border. The SE boundary of the study area lies near Helen, GA, and extends ~25km NW to Blairsville GA. For this study, The hillshade base for most of the panels has been inspected closely in ArcGIS, with the above-mentioned overlays turned on as needed, to identify and digitize the outlines any of the following slope movement feature classes created for this study: debris flow, debris slide, weathered rockslide, blowout, rockslide, and slope deposits. To date, over 350 landslide-related features have been digitized. The weathered rock slides appear to be dormant and old, and their toes impinge on streams that in several places align with long lineaments. Valley forming lineaments in the study area of up to 26km in length, have also been digitized, and some of them host numerous weathered rock slides. The 3m hillshade/slope overlay has also proven extremely useful in seeing through vegetated ground in the study area. With the new bare-earth LiDAR hillshade and colorized slope overlay, strata appear in many portions of the investigation area. The crisp sharp outline of Dahlonega Gold Belt mining features (some 175 years old) visible on the 3m hillshade shows how long lasting such ground disturbances can last before been naturally reclaimed.