Surface altitude of hydrogeologic layers of the Atlantic Coastal Plain of North and South Carolina
PP1773_unit_alt_grid is a polygon shapefile of surface altitudes for 16 hydrogeologic units as described in report 
Professional Paper 1773. Surface altitudes were interpolated and discretized to the 2-mile by 2-mile rotated grid 
used to simulate groundwater flow in the Atlantic Coastal Plain of North and South …