recovered to its present height in this region, and actually rose 

 to about 4 ft above modern levels during a period from about 

 1900 to 1200 yrs BP (Oaks and DuBar 1974). This would have 

 embayed water in all of these low-lying stream valleys, allowing 

 deposition of sediment and organic matter in the upper stretches 

 of the impounded portions, and initiating new peat deposition 

 in the lower segments. Sea level later fell about 10 ft and has 

 risen to its present level over the past 725 yrs. This recent 

 rise has elevated stream base levels and initiated more valley 

 filling. Lassiter Swamp is typical of these swampy streams in 

 that it is presently aggrading. Each spring flood brings sediment 

 from the uplands which is spread over the swamp floor, incorpor- 

 ating leaf litter and other organic matter and adding slightly 

 to its elevation. This process will continue for as long as 

 sea level remains at its present elevation or continues to rise. 



The role of beaver in the geology of these valleys is 

 unknown, but must have been a factor. If present during the 

 Wisconsin, their impoundments would have created a terracing 

 effect, slowing the rate of stream downcutting. Historical 

 records show that they were present in the post-Wisconsin 

 period, when their dams may have contributed to the rapid 

 filling of swamp bottomlands. It is possible, for instance, that 

 in the absence of beaver, delayed filling of upper Bennett's 

 Creek might have caused the stream to remain navigable as far 

 as Sunbury. That this filling is very recent is indicated by 

 the remaining holes in the channels of Lassiter and Duke Swamps. 

 The activities of recently returned beaver, which have constructed 

 dams in excess of 2,000 ft across the swamp, give some indication 

 of their potential for affecting local geology. 



PRESENT PLANT DIVERSITY MP ORIGINAL FLORA 



There are six major forest community types within the 

 natural area (see analysis of communities CT-A through CT-F) , 

 not including the disturbed pine successional areas found over 

 much of the uplands. In addition, there are numerous minor 

 community types which were not analyzed. These include some 

 distinct forest types of very limited extent, and a number of 

 aquatic communities that are either seasonal or ephemeral. 



CT-A. CYPRESS-TUPELO SWAMP FOREST ( Taxodium distichum (emergent) /Nyssa 

 aquatica / Acer rubrum-Fraxinus caroliniana / Saururus cernuus . 



This community appears to be climax for the wettest portion 

 of low lying fluvial swamps in the county. Because of proximity 

 to sea level, it occurs where the water table is never more than 

 a few inches below the surface, even in the most severe droughts. 

 A few acres of this type in Lassiter Swamp may represent a 

 remnant of the virgin forest of the area. The state record tupelo 

 ( Nyssa aquatica ) is found in this stand. A larger area has been 



95 



