MacMillan : shores at lake of the woods. 961 



IX. Classification of shores with reference to soil currents. 



A. Grumbling shores . 



1. Precipitous shores upon which the force of gravity acts strongly. 



2. Shores of a texture readily hroken. 



3. Shores exposed to strong weathering influences. 



B. Firm shores. 



1. Low or rounded shores upon which the components are disposed in 

 stable equilibrium. 



2. Shores of a Arm and resistant texture. 



3. Shores protected from strong weathering influences. 



X. Movable shores. 



A. Shores moved by the wind: e. g. Sand dunes. 



B. Shores moved by wind and water: e.g. Floating bogs. 



C. Shores moved by water: e.g. Beaches facing currents or eddies. 



The ten groups of shore-types given above scarcely exhaust 

 the possibilities of instructive classification but the more im- 

 portant groups have been included in the scheme. It becomes 

 evident that the consideration of a given shore must include a 

 wide variety of judgments and observations and in any given 

 example of shore a large number of factors must be taken into 

 account before a reasonably complete comprehension of it as a 

 station for plant individuals or plant formations can be formed 

 in the mind. Its exposure, contour, slope, texture, color, chem- 

 ical composition, physical structure, temperature, moisture, 

 nutriment content, illumination must all be given due consider- 

 ation. The influence upon it of rains, dew, snow, ice, surf, 

 spray, wind, currents of water or of soil and the force of grav- 

 ity must be regarded, and since not one condition alone but 

 permutations of all of the conditions in varying degree are in 

 every case to be distinguished, it would seem that a reasonable 

 explanation of the endless diversity of landscape might very 

 well lie in the diverse qualities of the substratum upon which 

 vegetation disposes itself. But when to all this is added the 

 endless complexity of biological factors — the symbioses, the 

 struggles between individuals and formations, the ecological 

 adaptations and distribution devices, the hybridizings and all 

 the historical, developmental and evolutional phenomena — the 

 student may well hesitate, so interminable is the coil. Yet if 

 the theoretical possibility of complete explanation under con- 

 ditions of complete comprehension of the data be taken into 

 the mind much has been accomplished. The position of a given 

 plant or of a particular formation at some spot on the crust of 



