Coastal Processes
By John Paul Lilly
Associate Professor Emeritus, Dept Soil Science
North Carolina State University
During all these millions of years of sea level rise and fall, land to the west was eroding and sediments were being carried eastward to the sea and deposited. These marine sediments built up to great depths over the bedrock. The marine sediments in Washington County are 2,500 feet or more thick. The landscape of the county reflects its marine history. The landforms of Washington County were shaped by the same forces at work today on the Outer Banks and on the sea bottom.

During times when the land was not covered by the sea, some of the sediments were moved and redeposited by streams and by wind. The rivers laid down deposits of sediments that are now called river terraces. River terraces parallel the river and become higher and older as the distance from the river increases. Each terrace is typically fronted by a sand ridge, deposited by the river as a natural levee when the river overflowed. Natural levees form when streams overflow their banks and the sediment-carrying capacity of the flowing water decreases. The heaviest materials and the ones that drop out first are the sands, forming sand ridges on the stream banks. Plymouth is built on a series of old river terraces that were deposited by the Roanoke River over many years. The town rises in steps as the distance from the river increases. An excellent example of an older levee is the sand ridge on the north side of Third Street where the old Baptist cemetery is located. The Latham House is also located on an old levee. Roanoke Shores and the Weyerhaeuser Paper Mill are built on the present natural levee of the Roanoke River. The land around Plymouth is a complex mix of river deposits and remnant dunes. Rolling Pines is built on an old dune field. The sand ridges along Mackeys Road were dunes formed off the old Roanoke River, and the sand ridges along Newland Road near Cherry are dunes that formed along the Scuppernong River. In general, these old dunes are the highest points around. Mountain Canal at Lake Phelps got its name from the large dune it cuts through.

The older marine sediments are responsible for the springs and artesian wells that were a part of Washington County's early history. "Cool Springs" near Plymouth was named for its springs. In addition, by some accounts, the original name for Creswell was "Cool Springs". Artesian wells or springs occur when an aquifer under an impervious layer of rock or clay is recharged at a higher elevation. This causes the water to be under enough pressure to force it to the ground surface. Artesian wells existed in downtown Plymouth until relatively recent; ceasing to flow as pumping by the town and other users relieved the artesian pressure.