along a wet topographic low at the foot of the Suffolk Scarp, 

 south into the Perquimans River. The disturbance history of the 

 area, however, prevents the advancement of this hypothesis with 

 any degree of certainty. 



Mantling of the Dismal with peat, during the period 8,900 

 to 6,000 years BP, would have slightly raised the base level of 

 Corapeake Swamp, terminating further valley carving. This 

 probably initiated a period of slight aggradation, bringing the 

 swamp bottomland to its present elevation of just under 25 feet 

 MSL near the mouth. 



The rate of post-Wisconsin erosion from the surrounding 

 uplands should be considered minimal. However, it is likely that 

 small quantities of fine sediment and organic matter would be 

 transported during times of heavy rainfall and deposited in the 

 Dismal. This may have resulted in a soil with a mineral fraction 

 intermixed with alluvial organics and those formed in situ. 

 Fanlike deposition in a deltaic area at the mouth of Corapeake 

 Swamp may have created the basis for a marsh. 



The exact nature of the original hydrology is unknown. Water 

 was received from rainfall and from Corapeake Swamp. It is also 

 possible that ground water may have been obtained from beneath 

 the Suffolk Scarp. The porous Norfolk sand underlies the site but 

 stops at the scarp, its western depositional boundary (Oaks and 

 Coch 1973) . An older aquifer beneath the scarp could deliver 

 water to the Norfolk sand from a recharge area to the west. The 

 current potentiometric studies of Gammon and Garrett may shed 

 light on this possibility. 



It is also plausible that the marsh may have received water 

 from elsewhere in the swamp. If there were peat accumulation 

 toward the center of the Dismal (now reduced by post-drainage 

 fires) , water from rainfall could have flowed west to the toe of 

 the scarp. and then north or south to an outlet. However, neither 

 this effect nor an artesian source of ground water would 

 necessarily be required to explain the existence of a marsh. 



The present woody invasion of the last marsh remnant 

 represents the current stage of succession after nearly 40 years 

 of fire suppression. Fire protection has been particularly 

 effective for the past 15 years. Any wildfire in the Dismal Swamp 

 is considered to have "project fire potential" by the NC 

 Division of Forest Resources and is promptly dealt with. The 30 

 acre remnant marsh is surrounded by a disturbed area of about 

 300 acres, clearly visible on aerial photography. There is 

 historical evidence of a much larger size in the past. 



47 



