SAND-WAVES IN TIDAL CURRENTS 299 



secutive sand- waves was 23' 5 7 per cent, of their 

 average height. 



The following table shows the details of the 

 measurements : — . , 



Series of Fifteen Sand-waves in the Estuary of the 

 South Esk at Montrose, proceeding Downwards — 

 i.E.^ IN the Direction in which the Waves Face. 



19 „ o „ 



Average ratio of length to height = 1476, 



All my measurements of these large sub-aqueous 

 sand -waves have been made after the tide had 

 wholly receded and left them' bare. The last 

 runnings of the ebb over the crests (which I 

 observed fromj a boat to be rapid) probably 



12 



