MacMillan : shores at lake of the woods. 1009 



III. Herbaceous talus formations. The characteristic plants 

 are various grasses, Campanula, Heuchera and Houstonia. Such 

 grouping arises even on small talus blocks of relatively new 

 formation if the surface condition is such as to retain the soil 

 that is formed, or to hold soil or silt of drainage. 



IV. Shrubby talus formations. These may be coniferous, 

 with the Junipers as the dominant plants, or metaspermic, with 

 such plants as Populus. Much depends upon the vegetation 

 of the back country in the establishment of shrubby talus 

 groups, yet light seeded plants like Populus have an evident 

 advantage. On large talus blocks it is not uncommon to see 

 small shrubs of Populus tremuloides rooting themselves, to- 

 gether with diminutive plants of Pinus divaricata or the 

 Junipers. 



V. Arboreal talus formations. On talus blocks it is not com- 

 mon to find large trees established, unless the block itself is 

 so large that it might well be considered under the general 

 class of rock-shore. Yet sometimes a talus block with a 

 pocket-like depression may collect soil in this depression and 

 give foothold for a tree. The tree in such a case is almost al- 

 ways coniferous, the hardwoods preferring crevices. 



All of these types are pure talus types and no consideration 

 to the intermixture of sand or soil that begins as soon as a 

 talus slope is established, has been given. In each of the five 

 groups a trace of zonal distribution is to be discovered, occas- 

 ioned by the difference in exposure of the perpendicular sur- 

 faces, those toward the lake being differently affected from the 

 ones facing in other directions. Yet, since the blocks may be 

 close together, they shade each other to such an extent that 

 the whole slope can hardly be regarded as a symmetrical area 

 of plant establishment, and the distribution is characteristic- 

 ally azonal. 



Of the pure talus-block type of distribution there are a great 

 many varieties owing to differences in exposure, slope, temper- 

 ature, illumination, moisture and biological conditions. On the 

 whole, such formations are less abundant than the mixed talus. 

 Coarse talus may be filled in either by sand from the lake or by 

 soil derived from one of three sources — from the off-shore vege- 

 tation, from the talus-block vegetation or from inland areas 

 whence it drains down upon the talus slope. However, it may 

 happen, very commonly the spaces between talus-blocks come 

 to be filled with soil or with sand. In the first instance there 

 develops in a coarse talus- bed about the same conditions that 



