142 CHARACTER OF SURF 



six, or even more (fig. 39), at different stages of the tide. In localities 

 where shoal spits or bars extend out from the tide line, alternating 

 with deeper gullies, the surf belt is likely to be interrupted over the 

 latter by lanes of unbroken water, extending close into the strand. 

 And the presence of a lane of this sort, between patches of surf, usually 

 indicates a gully, if it persists in the same location, for while similar 

 lanes are to be seen wherever the wave crests are narrow sidewise, they 

 are short-lived in that case, developing now here, now there. The 

 effects of bars and gullies of this sort, like that of the angle of slope of 

 the bottom in general, is often dependent on the stage of the tide, as 

 illustrated by the differences in the surf pictured in figure 40 which 

 was photographed from the same view point, but at high water in 

 the one case, at low water in the other. 



The types of surf that result from the interaction between bottom 

 contours, shapes and sizes of waves, and stage of the tide may be 

 classed roughly as follows: 



a. A single line of breakers with their crests dashing directly 

 against the shore line (figs. 28 and 34). This type is characteristic of 

 the surf that develops against steep ledges and against breakwaters 

 that rise from a depth of a fathom or more, or on any steeply sloping 

 beach when the waves are small. 



b. Breakers close in to the shore, with a belt of foaming water be- 

 tween them and the beach (fig. 27). This type is encountered most 

 often along steeply sloping beaches when the tide is high or nearly so. 



c. A single nearly continuous line, with lower breakers inshore from 

 it. This condition is commonest in moderate weather where swells 

 are running in over an even and gently sloping bottom. 



d. Two, three, or more nearly continuous lines of breakers, the 

 outermost of which is usually the highest but sometimes with all of 

 approximately the same heights (fig. 39). Like the last, this type 

 occurs most frequently in moderate weather when swells are moving 

 in over a gently sloping bottom. 



c. Several lines, covering the surf area as a whole, and varying 

 in number not only from moment to moment, but from place to place 

 as well. Such a surf is often observed during onshore winds of mod- 

 erate strength. 



/. Confused breakers in indefinite lines from seaward, grading into 

 a breaking sea offshore (fig. 35). This pattern is characteristic of on- 

 shore storms, whether on beaches or against rocky coasts (fig. 41). 



