326 WAVES OF SAND AND SNOW 



In order to examine the effect of the currents 

 of the sea in forming the larger kind of sand- 

 waves I visited Mundesley, on the north coast 

 of Norfolk, where owing to the form' of the coast 

 the tidal currents might be expected to run strongly- 

 parallel to the shore. On April 15, 1900, withj 

 a light off-shore wind, the sands exposed at low 

 tide were mostly smooth, but in the " low," or 

 narrow, depression parallel to the beach there were 

 well-preserved sand-waves, the crests of which were 

 at right angles to the shore, whereas the crests of 

 ripple-mark formed by waves are parallel to the 

 shore. The length of the sand-waves was 4 feet. 

 During the afternoon the wind came on to blow 

 with moderate force in a long-shore direction, and 

 next day the sand-waves in the " low " had a length 

 of 1 1 feet 6 inches. 



The large sand-waves on the North Goodwin 

 Sands are evidently formed by currents, not by 

 swell. I visited this sandbank on May 12, 1900. 

 The ridges faced in a northerly direction — i.e., were 

 opposed to the waves and to the light wind pre- 

 vailing at the time. The reason why they faced 

 with the flood and not with the ebb was evidently 

 that the higher sands to the north were uncovered 

 three and a half hours after high water, whereas 

 the ebb current does not commence until four and 



