178 



PROCEEDINGS OP THE AMERICAN ACADEMY, 



the ocean current and the local wind current do not have a chance to be 

 relatively so effective. It may be stated as a general principle that the 

 most effective agent of shore development upon the inner shoreline of 

 drowned topography is the tidal current. Broad bays form a middle 

 ground where any of the three forces may be the strongest. Upon the 

 outer shoreline the ocean eddy currents are the most effective, while 

 upon lakes and inland tideless seas the local wind currents are the most 

 important factor. The movement of the land waste is in all three cases 

 due largely to the action of the waves. 



Offset; Orerlap ; Stream Deflection, Figures 6, 7,8. — The three 

 criteria of form by which the dominant current alongshore may be in- 

 ferred are offset, overlap, and stream deflection. The three usually 

 occur together, but each is found alone. 



Figure 6. Offsets. Figure 7. Overlaps. 



V 



Figure 8. Stream 

 deflection. 



Types of offset without accompanying overlap are given in Figure 6. 

 Overlaps are commonly accompanied by offsets of the shore curves in the 

 same direction, as is markedly the case in Fire Island inlet, Long island 

 (C. S., 119). One shore curve offsets another when the curve itself or 

 the continuation of the same passes to seaward of the next succeeding shore 

 curve. "When this offset is slight, it may be perceived by looking along 

 the shore curve, putting the eye close to the map. 



The typical example of offset without overlap is on the west coast of 

 Jutland (Denm., Thisted), where the currents are known to be from the 



