GIS-BASED ANALYSIS OF BEDROCK STRUCTURE AND DRAINAGE MORPHOMETRY IN THE RICHMOND NORTH (KY) QUADRANGLE

We present the results of a GIS-based approach to help understand structural control on drainage morphometry in the Richmond North (KY) quadrangle. First-, second-, and third-order tributaries of the Kentucky River were mapped and digitized with ArcGIS using orthoimagery and a 20 ft DEM. These results were used to determine the orientations and lengths of the tributaries, which clearly reveal systematic trends in the higher-elevation areas; tributaries closer to the river are predictably dendritic and non-systematic, and are excluded from this study. These data, with topographic maps and GPS, were used to locate outcrops of exposed bedrock along stream beds and road cuts. The orientation of joints was measured with standard field techniques. Joint and stream orientation data were plotted on rose diagrams created by hand and with GeoRose. Joint orientation data show two major trends: West-Northwest and North-Northwest. Stream orientation data show two major trends as well: West-Northwest and North-Northwest. With correlations at both the West-Northwest and North-Northwest orientations, the data strongly suggests that joints could have some influence on local stream orientations. The origin of these joints is likely from activity along the Tates Creek and Richmond faults, two minor faults that trend Northwest, which lie within the Richmond North Quadrangle. These fall between the Kentucky River and Irvine-Paint Creek Fault Zones, two branches of the Lexington Fault System, and were most likely formed from activity from these major fault zones. The Lexington Fault System likely originated from the stresses of uplift and subsidence which formed the Cincinnati Arch located just west of the Richmond North Quadrangle, and the surrounding basins. The Cincinnati Arch passes through Tennessee and Kentucky in a Northeast direction. The Kentucky River and Irvine-Paint Creek Fault Zones branch off of the Lexington Fault system to the east, and were most likely formed from the subsidence of the Appalachian Basin.