Another geomorphic change resulting directly from "Audrey" was the 

 deposition of large colloidal clay masses along certain portions of the shore- 

 line. This fine-grained material has in recent years been gradually blanket- 

 ing the coast westward from the Atchafalaya River mouth as that distributary 

 has received more and more discharge from the Mississippi. During the 

 hurricane two large masses of this gelatinous clay were transported and 

 stranded as arcuate deposits across the beach and marsh at the shoreline. 

 Both were about two miles in length, up to a quarter mile wide and three to 

 four feet in thickness where measured. They were apparently deposited as 

 units for they have sharply defined limits. The arcuate clay masses are con- 

 cave landward and were breached in their central portions by runoff waters 

 following the hurricane. Since the storm these deposits have solidified and 

 compacted and will ultimately become an integral part of the Recent marsh- 

 land stratigraphy. 



A third type of geomorphic change resulting from the hurricane was 

 caused by runoff waters escaping the inundated area. This process gradually 

 abated over a period of time but caused breaching of the shell-sand beaches 

 in numerous places. A detailed comparison of before -and -after aerial photos 

 indicates that the majority of these breaches were apparently formed by earl- 

 ier hurricanes and simply reopened by "Audrey". Since the storm, normal 

 littoral drift has resulted in the closure of most runoff channels. 



DISCUSSION 



Steers: Many of you may remember that in 1953 - Dr. van Straaten 



will certainly - there was a very severe storm in the North 

 Sea. The coincidence of a tidal surge and a severe storm 

 raised the level of the water in the North Sea about eight feet 

 above any previous known level. About the Scotch coast I 

 will say nothing, but on our own coast I saw results which 

 were very similar in many ways to what you just said. It 

 wasn't a hurricane in your sense of the word but there was 

 for a short time very strong wave action at an unusually high 

 level. Dunes were cut away, low beaches were flooded, on 

 the true marshes nothing extraordinary occurred, although 

 the water was for a time eight or ten feet deep when normally 

 the deepest would be a foot or so. On the Lincolnshire coast 

 which is not a marshland coast in the true sense of the word, 

 but is very flat and sandy, the beach was locally completely 

 swept away and a good deal of sand and gravel pushed inland. 

 Repeated measurements have subsequently been made of a 

 certain number of profiles between Mablethorpe and Skegness. 

 Even in the summer of 1958 in three cases they had not return- 

 ed to normal. 



One other fact is relevant: in the midst of the storm certain 

 cliffs were cut back very rapidly. Along the Suffolk shore 



33 



