A CASE STUDY USING OPEN-SOURCE R SCRIPT AND GOOGLE EARTH TO TEST FOR STRUCTURAL CONTROLS ON STREAM ORIENTATIONS AT ENO RIVER STATE PARK, ORANGE CO., NORTH CAROLINA

Rectangular drainage patterns at Eno River State Park of Orange County, North Carolina, are likely controlled by fracture and fault patterns in bedrock. Part of the Eno River, near Fews Ford, runs parallel to mapped N-striking Mesozoic normal faults and diabase dikes (Bradley and Gay, 2005, Bradley, 2007). The Late Proterozoic Carolina Terrane metavolcanic rocks contain NNE- and WNW-striking sets of fractures that parallel the dominant stream directions of the Eno River in the park, plus a minor sub-horizontal WNW-striking set. Strike and dip of fractures in the area were measured at eight outcrops (n=334) and symmetrical rose plots and equal-area Schmidt diagrams were produced using open-source R script then placed into Google Earth to compare the directions of the Eno River to the strike data. The outcrop-scale fractures measured in this study mimic the regional-scale structural patterns and may be coeval with either Triassic extension or Jurassic dike emplacement. The result of this comparison supports the proposed connection between drainage patterns of the Eno River and pervasive Mesozoic-aged brittle structures (Bradley, 2012).