300 WAVES OF SAND AND SNOW 



flattened the iWaves somewhat by ploughing' off the 

 crests and depositing sand in the troughs. On the 

 other hand, the final escape of the water is by a 

 current which flows laterally along the troughs and 

 may perhaps deepen them. 



The rate of advance of three of the ridges was 

 measured with the aid of stakes driven deeply into 

 the sand. Between March 7th and 8th — i.e., as 

 the result jof two ebb tides — the ridges had adVancea 

 25 inches, 25-5 inches, and 27-5 inches respec- 

 tively — i:e., an laverage of 13 inches during one 

 ebb tide. 



During April, 1900, I went to see the sandbanks 

 in the estuary of the River Severn. The first which 

 I examined were those just above Severn Bridge, 

 more particularly the shoal nearest the west bank 

 which is named on the ordnance naap the Waveridge 

 Sand. Its surface when left dry was almost smooth, 

 except for the minute ripples called " current - 

 mark." On April 26th, at the time of spring tides, 

 I watched (the comimencement of the flood from 

 the Severn Bridge, which is nearly 100 feet 

 above the water. The Waveridge Sand has on its 

 west side the main channel followed by the ebb 

 current and on the east a blind channel, or swash- 

 way, between it and the Ridge Sand. I could see 

 the first rising of the water progressing slowly up- 



