PART II: GEOLOGIC SETTING 



6. The Isles Dernieres belong to a small, well-defined unit known as 

 the Mississippi River Deltaic Plain. The coast of Louisiana is fringed by a 

 band of marshland 16 to 130 km in width. The western band of marsh is more 

 narrow and is characterized by stranded beach ridges, or cheniers, surrounded 

 by marsh. This area of the southwest Louisiana coast is known as the Chenier 

 Plain. The eastern band of marshes contains gulfward-projecting natural levee 

 ridges bordering active and abandoned courses of the Mississippi River. This 

 eastern region, which spans almost 320 km of coastal Louisiana from Vermilion 

 Bay to the Chandeleur Islands, comprises the deltaic plain of the Mississippi 

 River (Figure 4). This plain encompasses the active and abandoned deltas of 



SCALE IN MILES 



JL^.^^m'f. >„. t .I^ ."- ! ;.« i'"* L '" 1 \»tmw<(Ln'<rrmi 

 _Jf MEXICO 



Figure 4. Location map of the Mississippi River Deltaic Plain 



