Formation of the Dismal Swamp peat did not begin until 

 around 11,000 to 12,000 years ago. During the Wisconsin, this 

 abandoned sea floor was a flat, sandy plain, vegetated by spruce, 

 northern pines of sandy soils ( Pinus banksiana and Pinus resinosa ) 

 and northern herbaceous species characteristic of open areas 

 (Whitehead 1972) . The mesic islands could have originated as dune 

 sands accumulated by dry winds sweeping across the sandy plain. 



A more likely hypothesis, however, might involve both 

 fluvial and eolian processes. Fluvial origin is suggested by the 

 fact that the entire series of ridges parallels the apparent sub- 

 peat course of the Pasquotank River. Sand, from the Sangamon beach 

 deposits atop the Suffolk Scarp, could have been carried down onto 

 the plain. 



Because of the elevational differences between the Talbot 

 and Pamlico terraces, the floor of the plain underlying the Dismal 

 served as base level for streams arising above the scarp. The 

 stream gradient was much lower to the east. As gradient decreased 

 abruptly, the sand portion of the bed load would have been 

 deposited as sand bars on the lower terrace. This alone, however, 

 would not be adequate to explain the present sand ridges, which 

 rise 6 to 8 feet above the peat beds. 



Significant sand movement through the stream system, across 

 the nearly level plain, probably occurred only during times of 

 high water. During dry periods the low sand bars would have been 

 exposed to drying and subsequent wind action. Wind-borne sands 

 could have been swept from the shallow stream bars and accumulated 

 in the adjacent woods to their present height. The parallel 

 ridges could represent sequences of accumulation during channel 

 migration. 



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