Vegetation of Northern Cape Breton. 435 



forested region, but their greatest display is seen in the barrens. 

 To the study of the origin, development and ecological relations 

 of the raised bogs here the author has devoted considerable 

 time, and it is hoped that the facts set forth in the following 

 pages may contribute materially to the knowledge of this 

 fascinating swamp type, as developed on this continent. 



General features of raised bogs and the influence of edaphic 

 factors on their local distribution. — The most bizarre feature of 

 a raised bog is the fact that it is higher toward the center than 

 toward the margin : the surface is convex, and the entire 

 structure frequently presents more or less the form of an inverted 

 saucer or watch-glass. The outline of a typical raised bog, as 

 viewed in cross section, is shown by Fig. 65, B. In this connec- 

 tion, it might be remarked that a slight convexity in the contour 

 of the surface is perceptible in some of the lowland bogs of 

 northern Cape Breton, and similar conditions are occasionally 

 noted in southern New England ; but in these cases the eleva- 

 tion of the middle portions at most is only a foot or two. In 

 the case of typical raised bogs the difference in height between 

 margin and center may be many feet: viewed from the surface 

 alone, and disregarding the contour of the underlying rock floor, 

 the higher portion may rise to a height of from fifteen to twenty 

 or more feet above the lower marginal portions. But that the 

 actual elevation of the bog surface above the rock substratum 

 in reality is often much less than it appears from superficial 

 examination will be apparent later. As shown by the cross 

 section (Fig. 65, C, f-h) the surface rises rather abruptly from 

 near the margin, then more gently, and the top of the bog may 

 be practically flat. The angle of slope along the steeper flanks 

 of a bog varies locally, but ordinarily the surface rises at the 

 rate of about one foot to fifteen or twenty on the level. Some- 

 times, however, the slope is much steeper: in one extreme 

 instance (foreground of Fig. 64), for example, a rise of three 

 feet in three and six feet in twelve was noted. The bogs vary 

 in size, but commonly they are many acres in extent, and in some 

 cases they stretch out uninterruptedly for more than a mile. On 

 the higher levels of the bog the ground underfoot, for the most 

 part, is quite firm and springy, but locally, particularly in the 

 vicinity of the small ponds which are frequently present, it may 

 be soft and spongy. The character of the surface vegetation 



