DRAINAGE. 



are not. well defined, the position of the edges of the wet portion varying 

 with the rainfall and the presence of the swamp flora. Some marginal 

 areas which are cleared have ceased to be swampy except in wet weather. 

 The swamp is heavily wooded and contains extensive canebrakes. The 

 swamp, which slopes gradually upward to the southwest, varies in altitude 

 from 12 to 22 feet above mean tide level. Near its center there is a 

 picturesque body of open water, known as Lake Drummond. This lake is 

 nearly circular in outhne, about 2^A miles in diameter, and until recently 

 its surface was slightly over 22 feet above mean tide level, being the highest 

 portion of the swamp. At one time its depth was about 15 feet, due in part 

 to the damming of the swamp by banks of canals, ^ow, owing to the 

 deepening of the canal feeder, the lake is only about 6 feet deep and the 

 surface correspondingly lower than it is known to have ever been before. 

 Its floor is largely covered with white sand. The lake water is light brown 

 in color, due to a considerable amount of finely divided vegetal matter in 

 suspension. It is thought to be perfectly wholesome, and as it is famous 

 for its keeping properties it has been used extensively for supplying ships 

 for long voyages. The lake is surrounded by woods, and at some points 

 cypress trees are found growing in the water. The depth of the water 

 decreases rapidly in the woods adjoining the lake, and over the swamp area 

 in general it is rarely more than 11/2 feet, except possibly in very wet 

 weather. The average depth is from 1 to 3 inches, but in many portions 

 the average depth is from 6 to 8 inches. In very dry seasons the amount 

 diminishes all over the swamp area. 



"Some marginal portions of the swamp have been drained for farming 

 land, for which the soil is admirably adapted. The swamp area known as 

 the Green Sea was originally a portion of the main swamp, but the Dismal 

 Swamp Canal, which traverses the eastern portion of the area from north 

 to south, has in a measure drained the intervening region. This canal sus- 

 tains the water level and the resulting swamp conditions to the west, but 

 has reclaimed from inundation a zone of considerable width to the east, an 

 area which is further drained by the branch ditch known as the Herring 

 Canal. The swamp flora is characterized by the occurrence of bald cypress, 

 juniper, black gum, and extensive canebrakes. 



"The swamps lie in shallow basins in the surface of the general terrace 

 of the Norfolk region. The basins are now filled to the general level of the 

 surrounding country with vegetal accumulations, which have a maximum 

 thickness of about 20 feet. In recent excavations for a gate on the feeder 

 about half a mile east of Lake Drummond there were exposed 10 feet of 



