636 



GUTLCHER 



[chap, 24 



r 



EJ«^'^^.'. 



Fig. 14. Part of Le Conquet estuary, Brittany, on September 5, 1951. (Photo. A. Guilcher.) 



Fig. 15. Same part ot Lu Conquet estuary on September 9, 195.5, showing erosion of high 

 marsh edges and outhers since 1951. (Photo. A. CJuilcher.) 



the minimum velocity required to erode a sediment after it has been deposited 

 is higher than the maximum velocity at which the same particles can settle: 

 this "scour lag" favours an excess of deposition. Likewise, the decrease in depth 



