184 WAVES OF THE SEA 



level during the outflowing current to be the same 

 as that during the inflowing current, so that the 

 resulting 'longshore transport by waves running 

 dead on shore may be nil, their effect during out- 

 flowing tide being equal and contrary to that during 

 inflowing tide. Leaving out of account for the 

 present the exceptional and rare positions where 

 tidal nodes occur, we see from the above that the 

 combined action of tides and onshore waves is to 

 sweep shingle rapidly up-channel from all salient 

 positions. In bays, the transport will be, on the 

 whole, up-channel, but much more slowly, on 

 account of the inflow and outflow currents of the 

 tide occurring at more nearly equal levels. Thus, 

 removal of shingle from headlands and accumula- 

 tion in bays would still be general even if there 

 were no co-operating causes, such as oblique waves 

 and stronger currents. 



Dr. Owens and Mr. Case, in their valuable book 

 on " Coast Erosion and Foreshore Protection," have 

 already called attention to the importance of the 

 relation between the times of commencement of 

 flood and ebb currents and the times of high and 

 low water in connection with the littoral drift, and 

 have cited the case of Southwold, Suffolk, where 

 the upper part of the foreshore is only exposed 

 to the flood current. I have worked out as above 



