960 MINNESOTA BOTANICAL STUDIES. 



4. Shores, the contour of which permits the surf to affect a broader area. 



5. Shores facing water of which the depth and character of the bottom 

 favors surf formation. Such shores are subjected to heavy surf. 



6. Shores provided with moveable bodies which, carried in the surf, 

 increase its impact-force. Among such bodies are flat pebbles and drift- 

 wood. 



7. Shores devoid of surf-barriers such as outlying bars or formations of 

 surf-plants. 



B. Shores protected against surf. 



1. Shores exposed to narrow expanses of water upon which the surf 

 is intermittent. 



2. Shores of which the slope diminishes the impact- force of the surf. 



3. Shores exposed toward quarters from which the prevailing winds are 

 unaccustomed to blow. 



4. Shores of which the contour limits surf action to a narrow area. 



5. Shores facing water of which the depth and character of the bottom 

 tends to inhibit surf-formation. Such shores are exposed to light surf. 



6. Shores destitute of moveable bodies which carried in the surf would 

 increase its impact-force. 



7. Shores provided with surf-barriers. 



VII. Classification of shores with reference to mechanical 



effect of ice. 



A. Ice-modified shores. 



1 . Shores of which the exposure, slope, shadiness, coldness and seclusion 

 from winds permit long continued ice-pressure extending into the late 

 spring, 



2. Shores of which the contour and slope favor ice-pressure. 



3. Shores of a texture readily modified by ice-action. 



B. Ice un-modified shores. 



1. Shores of which the exposure, slope, sunniness, warmth and accessi- 

 bility to winds prevents long-continued ice-pressure extending into the 

 late spring. 



2. Shores of which the contour and slope minimize the ice-pressure. 



3. Shores of a texture not easily modified by ice-action. 



VIII, Classification of shores with reference to currents of 



water. 



A . Current-modified shores. 



1. Shores bordering upon strong currents. 



2. Shores of a texture easily modified by currents. 



B. Current-unmodified shores. 



1. Shores bordering upon weak currents. 



2. Shores of a texture not easily modified by currents. 



