302 



George E. Nichols, 



frifolia and Chio genes hispidula, vanish almost completely ; 

 others, such as Pteris aqiiilina, Cormis canadensis, Epigaea 

 repens, and Moneses uni flora, become much less common; while 

 still other species, such as Polystichum acrostichoides, Smilacina 

 racemosa, and Saniaila marilandica, which were poorly or not at 

 all represented in the coniferous forest stage, come to occupy a 

 more or less prominent position. 



Figure 14. — Granitic talus of the prevailing type; north of Cheticamp. 



d. THE ASSOCIATION-COMPLEXES OF TALUS 



With reference to the size of the component rock fragments 

 and the consequent degree of stability of the rock mass, talus 

 slopes (Fig. 14) vary greatly. Two extreme types may be dis- 

 tinguished: the Boulder Talus and the Gravel Slide. Boulder 

 talus consists essentially of large rock fragments (sometimes 

 many feet in diameter), which tend to lodge together and inter- 

 lock with one another on the slope in such a way as to produce 

 a relatively stable rock mass. A gravel slide, on the other hand, 

 consists primarily of fine, loose rock debris, which is not held 

 together in any way but is constantly tending to slip further 



