Overview of North Carolina Coastal Plain Geology
The North Carolina Coastal Plain, covering an area of approximately 20,000 square miles, comprises 40% of the state. The flat to gently undulating surface of the Coastal Plain gradually increases in elevation westward from the coast to an average of 450 feet above sea level along the inner margin where coastal plain sediments pinch out against Late Proterozoic to Paleozoic crystalline rocks of the Piedmont. The Coastal Plain consists of a complex, wedge-shaped mass of sedimentary rocks that generally dip and thicken in an eastward to southeastward direction. These sediments overlie a crystalline “basement” composed of metamorphosed sedimentary and igneous rocks like those of the Piedmont. Figure 1 shows the depth below sea level to the top of crystalline basement and delineates the major tectonic feature of the Coastal Plain, a southeast plunging basement high known as the Cape Fear Arch.
Sediments composing the coastal plain section range in age from Early Mesozoic to Recent. They are predominantly shallow marine to marginal marine in origin, but a wide spectrum of sedimentary environments is represented.
Regional onshore (Brown et al., 1972) and offshore (Popenoe, 1985) studies have characterized the sedimentary package of the North Carolina Continental Margin as consisting of geometrically complex, unconformity-bounded sequences which exhibit a high degree of lateral lithologic variability. Although these studies agree with regard to the areal distribution and relative thicknesses of major chronostrati-graphic units in areas common to both, their authors propose different mechanisms to account for their observations.
Brown et al. (1972), based on
Figures & Tables
Southeastern United States–Guidebook is comprised of twelve field trips that were organized for the Third Annual Midyear Meeting held in Raleigh, North Carolina in 1986. The spectrum of geologic time represented in the Upper Precambrian, Lower Paleozoic, Mesozoic, Cenozoic and the very Recent. The geologic provinces are the Valley and Ridge, Blue Ridge Mountains, Piedmont, and the Coastal Plain. Besides North Carolina, trips include Virginia, South Carolina and West Virginia.