﻿Nichols: The vegetation of Connecticut 173 



fluctuating. It is highest during winter and spring, the seasons 

 of maximum precipitation; it is lowest in late summer, toward 

 the end of the season of minimum precipitation. In the following 

 paragraph, the writer has attempted to bring out, with the help 

 of diagrams (Fig. 2), the important bearing which these various 

 factors may have on the nature of lakes, ponds, and swamps. 



With reference to their relation to topography and water table, 

 four fairly distinct types of lowland may be recognized, (i) Per- 

 manent Lakes or Ponds. — ^Where the relationship between the 

 controlling factors, i. e. topography and water table, is such that 

 a tract of land is submerged to an appreciable depth by standing 

 water throughout the year (Fig. 2 , A) , it is obvious that a permanent 

 lake or pond will exist. It need hardly be remarked that such a 

 water body can arise only within a completely enclosed basin. 

 Lakes fed entirely by subterranean waters are not uncommon, 

 but more frequently this source of supply is supplemented by 

 surface streams. A permanent water body can exist in a closed 

 basin only where the amount of water flowing in exceeds the 

 amount lost through underground drainage plus the amount lost 

 through evaporation. (2) Intermittent Lakes or Ponds.— 

 Very often the relationship between the various factors involved 

 is such that a basin is filled with water in spring, but later in the 

 season, as a result of the lowering of the water table plus increased 

 evaporation, the surface water vanishes, leaving the bottom of the 

 depression quite dry, or else merely swampy (Fig. 2, B). Shallow, 

 intermittent ponds of this sort are of frequent occurrence, being 

 especially well developed in parts of the sand plains north of New 

 Haven. (3) Permanent Swamps. — It often happens that, in 

 spite of an abundant supply of underground water, topographic 

 relations are such as to prevent pond formation. Thus, seepage 

 water may keep the ground on a side hill wet throughout the year, 

 but as fast as the water reaches the surface it runs off to lower levels. 

 Similarly there may be a series of perennial springs along the base 

 of a hill, but in the absence of an enclosed basin of some sort to 

 contain the water, pond formation manifestly cannot take place, 

 and swampy conditions prevail. Ideal conditions for permanent 

 swamps are presented by the flat floors of the old glacial drainage 

 valleys, so common throughout central Connecticut. Lying well 



