resulted from thousands of hours of laborious field surveys done under difficult and dangerous 

 conditions, provide a picture of the landforms and vegetation patterns in the region as they existed 

 in the latter half of the 19th century. 



Figure 3 is a composite of individual section plats done as part of the township surveys. This 

 map shows a distinctive, pretzel-shaped portion of the Bayou l'Ours ridge system which lies within 

 the site-specific area considered in this study. As shown on the survey plats, main ridges of this 

 feature were more or less continuous. There was freshwater vegetation, notably maple (Acer 

 rubrum) and willow (Salbc nigra) swamps, between the ridges. Surveyor notes indicate that there 

 were bottomland hardwood forests, consisting primarily of live oaks (Quercus virginiana), on the 

 ridges themselves. Some of the lower ridges also had willow and maple growth. Adjacent areas 

 between this system and Bayou Lafourche were described in the surveyor notes as impassable, open 

 prairie marsh, or trembling prairie. 



PRE-CANAL CONDITIONS 



Aerial photographs taken in the 1930's and 1940's, prior to extensive canal dredging in the area, 

 indicate that landform conditions remained largely unchanged from those recorded on the township 

 plats. The natural levees formed a skeletal framework of low ridges which divided the area into 

 a series of enclosed and semi-enclosed hydrologic units (Figure 4). Around and between the ridges, 

 the surface was covered by virtually unbroken carpets of marsh. Drainage was primarily through 

 sheet flow guided by ridge trends in a general southeast direction. There were no well-defined 

 channels in the interdistributary basins or within the abandoned channels. The few ponds that did 

 exist were isolated, often ephemeral, and completely surrounded by marsh. Not only was the 

 vegetation freshwater, but also, the aquatic fauna as might be anticipated. 



Streams north of the ridges and south of Little Lake showed a characteristic drainage pattern 

 found within the center of the Barataria Basin and other interdistributary basins. This area was 

 predominantly fresh in character, but water-level fluctuations within the basin caused bi-directional 

 flow. 



There was a well-defined zone of marine tidal influence characterized by branching networks 

 of sinuous tidal channels extending north from the upper reaches of bays that interconnected to 

 Caminada Bay. Flow in the tidal channels within this zone was bi-directional. 



Analysis of historic map data indicates that there was a narrow transition zone between the 

 upper reaches of the zone of marine tidal influence and the fresh marshes and swamps. The tidal 

 stream network stood in sharp contrast to the unbroken carpets of grass in the fresh-to- 

 intermediate marsh. Estuarine-dependent organisms were restricted to the tidal zone. 



PIE-SHELL CONDITION 



An important distinction can be drawn between near-surface deposits and soils composed 

 predominantly of mineral sediments derived initially from the Mississippi River (allochthonous 

 sediments) and those composed predominantly of organic materials resulting from swamp and marsh 

 plants (autochthonous sediments; Figure 5). When the distributaries were active, the distinction 

 between the soils and topography of the natural levee ridges and intervening basins was 

 pronounced. During the abandonment stage, the basins became the site of organic sediment 

 deposition. As peats and organic clays accumulated in the basins, local relief became less 

 pronounced. Lowest elevations along the crest lines of the natural levee ridges controlled water 



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