The concept of a most favorable drift-producing angle is of great 

 value in explaining a number of shore line phenomena. Its application 

 in the explanation of the travelling foreland is illustrated in Figure 3. 

 It is assumed that the predominant wave action is from the left, that 

 wave action comes frequently from the right, but that waves from directly 

 offshore are rare. The curvature of the back AB is such that the angle 

 of incidence of the predominant wave action may approximate h$° at B. 

 Hence the quantity of beach material in motion increases progressively 

 from A to B. This increase can only take place at the expense of the 

 beach, and therefore the back AB is eroded. On the front BC the angle 

 of incidence of the waves from the right is normal near the center and 

 is so oriented elsewhere as to produce a movement of material toward the 

 center of the front. Hence accretion takes place on this face of the 

 foreland. 



It should be noticed that although the predominant wave action from 

 the left produces a drift toward the right along most of the main shore, 

 as is illustrated at points D and F of Figure 3* an opposite drift is 

 produced at E which is in the lee of the foreland and hence protected 

 from this wave action. As a result, beach material moves toward the 

 foreland from both sides. The constant accumulation of beach material 

 on the front of the foreland exceeds that eroded from the back, and the 

 foreland increases in size as it advances. 



Observation shows that travelling forelands ordinarily occur on 

 the shores of long, narrow bodies of water. This is what might be ex- 

 pected as such a body would provide an adequate expanse of water for the 

 generation by the wind of waves running with its longer axis but not 

 at right angles to it. The direction of travel of the foreland would 

 depend on the relative strength and frequency of the winds that blow 

 approximately parallel to the long axis and upon the relative expanse 

 of water to either side of the foreland. Figure k shows Cove Point, 

 Calvert County, Maryland, an example of a travelling foreland on the 

 west shore of Chesapeake Bay. 



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