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stones of fine stratification, and shales outcrop. Here, unequal 

 erosion gives rise to small shelves which collect the weathered 

 material, and thus forms a slope of which a considerable part has 

 a shallow soil and humus that are relatively unstable. This is 

 rendered more so by the seepage of water from the rock. Very 

 frequently in the spring landslides occur, caused by the saturated 

 soils higher up on the slope loosing their stability and sliding to 



Fig. 5. Undergrowth in the evergreen stage of the broad ravine. This type 

 is characterized by a low number of species most of which are evergreen. The 

 forms represented here are Taxus Canadensis, and Aspidium Marginale. 



the bottom under the force of gravity. Such slides are de- 

 structive to the vegetation as they not only completely uproot 

 all plants in their path, but remove the humus and soil, so that 

 the rock is left bare where they have passed. A single cliff of 

 this kind may show evidences of a dozen or more of such slides. 

 It is at once evident that an environment of this kind is not 

 well adapted to the development of a dense forest. The mois- 

 ture is sufficient, and the desiccating influences frequently not 



