Vegetation of Northern Cape Breton. 45 1 



Sometimes these ponds appear to be distributed quite indis- 

 criminately over the surface of a bog (e. g., see Fig. 65, A) : 

 particularly is this true on the higher, older bogs. But in other 

 cases their arrangement is very definite. To cite a specific 

 illustration of the latter sort : in one shallow, approximately flat- 

 floored valley (similar to that pictured in Fig. Gy) about a 

 hundred feet wide, there are ten of these ponds within a distance 

 of three hundred feet. All are more or less elliptical in outline, 

 twenty to fifty feet long by six to twenty feet wide, and they are 

 arranged, like a flight of steps, at right angles to the long axis 

 of the valley floor. Between the surface of the lower pond in the 

 series and that of the upper there is a vertical difference in eleva- 

 tion of five feet. It may be further noted that the rock floor 

 beneath this bog, as determined by soundings, is quite even and 

 that the peat is uniformly about four feet deep, except around the 

 down-hill margins of the ponds where it is banked up higher. 

 From the study of this and other like cases, there seems little 

 question that a large proportion of the ponds associated not only 

 with wet bogs but also with dry bogs have originated in the 

 manner here described. The absence of any relationship to the 

 character of the underlying topography is exemplified by ponds 

 d and e in Fig. 65, C. 



Leaving for the moment the consideration of these ponds, the 

 further history of the bog as a whole may be briefly detailed. 

 Largely through the activity of the mesophytic cushion- forming 

 sphagnums, the general level of the surface has been raised and 

 bog meadow eliminated. These mesophytic sphagnums continue 

 to predominate and to build up the substratum for a locally 

 variable length of time: frequently a wet bog association may 

 represent an edaphic climax. But although the nature of the 

 environment may be considerably modified by the influence 

 of the ponds referred to above, it is apparent that, as a rule, 

 sooner or later, as the surface rises higher, the conditions will 

 become less favorable for the mesophytic sphagnums, while 

 at the same time they will become more favorable for the 

 xerophytic cushion-forming species {S. fuscum, S. capillaceum 

 tenellum, S. tenerum). As time goes on, these latter species, 

 which in wet bog constitute merely a subordinate element in the 

 vegetation, gradually become the predominant forms, and wet 



