Qrt 



Q/t 



Overlapping Offset 



Qrt 



Adequate 

 updrift source j^ 



Q/t 



Length of arrows indicotes 

 relative magnitude of 

 Longshore Tronsport Rate 



Updrift Offset 



Inadequate 

 updrift source 



Downdrift Offset 



Qrt Qit 



Negligible Offset 



(Galvin,l97l ) 



Figure 4-58. Four Types of Barrier Island Offset 



4-148 



