The Big Swamp
By John Paul Lilly
Associate Professor Emeritus, Dept Soil Science
North Carolina State University
The central part of the county is a flat plain (the Pamlico Terrace) that was the sea floor when sea level was higher. The entire plain slopes gently toward the east at about six inches per mile. The natural drainage is poorly defined because it is a young geologic surface. In the last 10,000 years, a complex of wetlands has developed on the surface. This is part of the largest wetland complex in North Carolina. It covers the major part of five counties (Washington, Beaufort, Tyrrell, Hyde, and Dare) on the peninsula between Albemarle Sound to the north and Pamlico Sound to the south, and is bounded to the west by the Union Chapel and Pinetown Scarps. The central part of the wetland complex is the largest pocosin in the world. Despite these superlatives, this wetland has no single well-known name. In contrast to the Great Dismal Swamp of North Carolina and Virginia, and other North Carolina wetlands such as Open Ground Pocosin, Green Swamp, Angolan Bay, and Holly Shelter, this wetland has no common name. McDonald and Ash (1981) simply refer to the whole peninsula from the Suffolk Scarp to the Alligator River as the "Washington-Hyde-Tyrrell Pocosin System". On county road maps, the western portion in Washington and Beaufort counties is called The East Dismal Swamp, but this name is seldom used. Instead, parts have been given names related primarily to land development activity. Names such as the Parker Tract, Wenona, Wonderland, Terra Cecia, North Slope, South Slope, North Line, Carolina Meadows, Grassy Ridge, Hyde Park, and probably others. Drainage of the southern portion is to the Pamlico Sound by way of Bath Creek, the Pungo River, and other streams. Drainage of the northern part is to the Albemarle Sound by way of Conaby Creek, Mackeys Creek, and the Scuppernong River

The wetlands of the Peninsula include the bottomland forests on the flood plains of the Roanoke and Scuppernong Rivers, the non-bottomland swamp forest of the central part of the county, the cypress forest north of Lake Phelps, and most especially, the pocosins of the interior. Pocosins are isolated wetlands, which are unique to the southeastern United States and concentrated in North Carolina. The term comes from the Algonquin Indian words meaning, "swamp on a hill" -- related to the fact that are often higher than the surrounding terrain. Pocosins normally develop in blocked fossil drainage areas, and are nutrient poor, receiving all of their nutrients from the sky. Soils vary, but often consist of deep organic soils called "peat," which develop because of the slow rate of decomposition of organic matter in flooded soils. Deep peats often contain "fossil" cedar, cypress, and heart pine logs as evidence of their previous vegetative state (Rader, 1989). The factors responsible for deep organic accumulation are high rainfall, flat topography, large distances between streams, and shallow depth to impermeable layers. During pocosin development, this caused ponding, anaerobic conditions, and accumulation of organic debris that further impeded water flow and enhanced the process of swamp development. These deposits characteristically occur at elevations higher than the surrounding mineral soils. Their only source of water is rainfall, either directly or as lateral flow. Measurements elsewhere in the region have established that peat formation last began about 8900 (plus or minus 160) years B. P. (Oaks, 1964). The highest point in the pocosin is near the Washington, Hyde County line south of Lake Phelps.

Pocosin vegetation is also unique, consisting of broad-leaved and mostly evergreen shrubs including titi, red bay, sweet bay, wax myrtle, gallberry and zenobia. These shrubs are usually accompanied by a thin overstory of pond pine. Pocosins are often made almost impenetrable by an interlacing of green briar. In general, pocosins are classified as "scrub-shrub bogs."

Pocosins and related vegetation types are maintained by three factors: soil saturation with water, depth of the organic soil, and frequency of fire (Otte, 1981). In deep peats with infrequent fires, Atlantic white cedar may dominate, in almost monotypic stands. Atlantic white cedar is highly prized by the forest product industry, and was heavily utilized by the Roper Lumber Company for the production of lath, shingles, and other products. Relatively few stands remain intact, but at one time, there were thousands of acres of Atlantic White Cedar in Washington County.

Pocosin vegetation burns fiercely once ignited, and peat fires may burn for months underground. Small, frequent fires help maintain the pocosin vegetation but large, infrequent fires can be extremely destructive because some or all of the organic soil may be consumed as well as the surface vegetation. Pocosin fires have occurred many times over the years, and the present depth of the organic deposits in Washington County is undoubtedly much less than in years past. The Pettigrew papers contain accounts of fierce fires burning for many days south of Lake Phelps (Lemmon, 1971, 1988). In some cases, fire, drainage, and cultivation have resulted in the loss of the entire organic surface. Dolman and Buol (1967) estimated that the farmed land just east of Railroadbed Road (North Slope area) had lost about 70 inches of organic surface. Aside from fire, all drained organic soils will inevitably lose organic matter and subside over time.

The most recent large destructive fire occurred in the spring of 1985 (the Allen Road fire) when over 100,000 acres of land burned in three counties. On average, that fire removed 6-12 inches of organic surface from the pocosin south of Lake Phelps.

The Blackland agricultural area of Washington County was once covered by pocosins and other wetlands. Sites without deep peat were converted for agricultural and silvicultural use, starting in early historical times and proceeding until the early 1980's. Dense drainage systems are necessary for successful farming in most former pocosins (Lilly, 1981a). It has been estimated that Washington County originally had about 180,000 acres of wetlands (Rader, 1989), out of a total area of about 215,000 acres (about 84% of the land area). The estimated acreage in 1982 from the National Wetland Inventory was 58,704 acres remaining, much of it highly modified for forestry production and other uses. It should be obvious that the history of the county includes a heavy emphasis on drainage, and that wetland issues continue to be of great importance to the county. Summaries of the history of the development of North Carolina pocosins are presented by Lilly (1981b) and McMullen (1984).