COASTAL MARSHES OF LOUISIANA 



Richard J. Russell 



Director, Coastal Studies Institute 



Louisiana State University 



Contract N7onr -35608 

 TaskNR 388-002 



Dr. Morgan, who was to present this paper as the concluding portion of the Louisiana 

 section of this conference, was unable to be present, and I will attempt to fill in for him from 

 some of his notes. 



Dr. Morgan served as the Field Supervisor in the project, and Mr. Treadwell was one of 

 five district investigators. We budgeted nine months for training time and fifteen months in the 

 field for the district investigators. If our group had a full day at this conference instead of an 

 hour or so to review the Louisiana project, we would have included the other investigators. 

 They all have interesting stories. 



Apart from the five district investigators, Mr. Mclntire acted in the capacity of tying the 

 whole thing together. He ranged throughout the various districts working on the problems of 

 chronology and relative dating. 



As we divided the Louisiana region, three of the investigators had areas of quite recent 

 delta growth. Mr. Treadwell's talk concerned an area of recent growth in several deltaic suc- 

 cessions, but all quite recent as far as the whole history is concerned. Two of the investigators 

 covered roughly the western half of the Louisiana coast, and Dr. Morgan had intended to speak 

 particularly about their region. 



There is a little story that I am just going to sketch in a few minutes, which is somewhat 

 dramatic as to what has happened on the western coast. In general, the eastern portion of 

 Louisiana is the region of growth whose history does not go back too many centuries. The 

 western coast, in a sense, is much older and smoother. Wave erosion in general has taken off 

 the irregularities of the coast, so that there is quite continuous beach. In driving cattle west- 

 ward, it is only necessary to swim them three times across this whole area. A great many 

 cattle are grazed down here in the salt marshes, and actually the beach, as a cattle drive, 

 has some conse qu e nc e. 



This region is one in which there has been a history of alternation between periods of the 

 growth of marshes outward into the Gulf of Mexico, advancing the shoreline to the south, and 

 periods when the beaches formed by the waves are driven northward across the marshes. 

 Within recent centuries, most of this western half of Louisiana has been a region in which the 

 beach has been driven back across the marshes. 



Comparing the old Land Office Survey maps and whatever data we could get, some over 

 20 years old, we published to the effect that this coast on the whole was receding at the rate of 

 about 600 feet per century. As a matter of fact, now that we have aerial photographs of this 

 entire region taken in 1952, in addition to those of 1932, we know the average recession of this 

 coast was 800 feet within this twenty-year period. The beach has been encroaching on the 

 marsh much more rapidly. It also has grown in size. Anything coarse which can be picked up 

 by the waves has been accumulated back on the beach. 



The "coarse" material in this region is, for the most part, very fine sand or coarse silt, 

 so that while the beaches are quite firm and appear white, still they are composed of materials 

 among the smallest sand sizes. Other coarse materials are shells, bottles, pieces of steel 



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