Vegetation of Northern Cape Breton. 



i^S 



are practically restricted to the intervales or to the adjoining 

 slopes. From the standpoint of their physiographic origin, the 

 intervales are largely the result of stream activity, and their 

 vegetation in part is that of the boulder plains and flood plains 

 which are still in the course of formation. But in large part, so 

 far as the vegetation is concerned, the influence of the stream 

 is of merely historical significance. In the case of boulder plains 

 and flood plains, local soil as well as local atmospheric factors 

 have to be taken into account. 



Figure 20. — The Big Intervale along North Aspy River: floor of valley 

 at this point largely under cultivation ; in background, talus slopes in 

 various stages of f orestation ; view taken toward upper end of intervale ; 

 compare Fig. 7. 



d. THE ASSOCIATION-COMPLEXES OF BOULDER PLAINS 



In extreme cases, vegetation may be almost wholly lacking on 

 boulder plains (Fig. 18). But such cases are not common. While 

 from a distance tHe lower and more frequently flooded portions of 

 a boulder plain may have almost the aspect of a desert, closer 

 inspection usually reveals, even here, a goodly representation of 

 shrubs and herb'aceous plants, which maintain a precarious foot- 



