The Orangeburg Scarp is a wave-cut, steep incline that forms the boundary between the upper and middle coastal plains. This escarpment cuts diagonally across South Carolina, passing near or through parts of Bennettsville, Hartsville, Sumter, Columbia, Orangeburg, and Allendale. As the scarp traverses the state, it reaches heights ranging from 180 to 215 feet above sea level.
The Orangeburg Scarp represents the limit of the ocean during the middle Pliocene epoch. As Earth’s climate changed over time, and as the processes of plate tectonics produced more or less lava on Earth’s surface, sea levels rose and fell repeatedly over millions of years. This resulted in worldwide sea level changes, the evidences of which are various escarpments visible along the edges of continents. The Orangeburg Scarp is a large, dramatic example that runs from North Carolina to Florida.
The Orangeburg Scarp can be seen in many places across the state. It is easily seen near the city of Orangeburg as it forms a steep grade down to the much flatter terrain of the lower coastal plain. It is also found along the Congaree and Wateree River valleys. In Columbia many important sites lie on the Orangeburg Scarp, including the State House and much of the campus of the University of South Carolina. During the late Pliocene sea levels fell dramatically, and as the sea levels fell, much smaller escarpments formed over the coastal plain, named the Parler, Surry, Dorchester, Summerville, and Bethera Scarps. The current escarpment forming in South Carolina is called the Cainhoy Scarp, found at the coast.
Murphy, Carolyn H. Carolina Rocks! The Geology of South Carolina. Orangeburg, S.C.: Sandlapper, 1995.