AND OTHER WATER WAVES 251 



prepared for it. Then the bore is produced, and 

 it is noteworthy in this connection that, according 

 to the observation kindly communicated to me by 

 Mr. D. Wintle, of Newnham -on -Severn, the bore 

 is more marked there at the commencement of 

 spring tides than after they have been running 

 for some days. 



In the lower reaches of the steep slope, and 

 above Beachly Point, the land water forms a 

 smaller proportion of the total, and the duration 

 of the ebb is shorter. The sands, as they are at 

 low water, are therefore not arranged so well to 

 facilitate the run of the ebbing waters, their dis- 

 tribution, on the contrary, exhibiting certain 

 features markedly favourable to the commencement 

 of an upward flow. This change of conditions 

 exhibits itself by the presence of swatchways, or 

 by-channels, such as that above referred to. 



How these are formed has been already indi- 

 cated, and may now be further explained. The 

 ebbing stream ponds back the flood, which conse- 

 quently makes another way for itself through and 

 across the sands. The relation of the two classes 

 of channel due to ebb and flow respectively has 

 been described "by the author elsewhere. 1 Briefly, 

 the low-water ebb channels are narrow, deep, and 

 1 Geographical Journal, August, 1901. 



