Atchafalaya Basin

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St. Martin Parish is made up of two major physiographic areas: Mississippi River alluvial plain and the terrace uplands (Murphy et al., 1977). Both landform categories were made because of the Mississippi River. The alluvial plain consists of recent fluvial deposits that were deposited by the Mississippi, Atchafalaya, and Red River during the Holocene Epoch, last 10,000 years. These accumulated deposits eventually give way to creating landforms such as backswamps and natural levees. Backswamps are low land areas that are built from silt and clay particle deposits. These particles tend to compact very easily thus making the area a lot lower than the surrounding landscape. In St. Martin Parish, the Atchafalaya Basin is a very popular backswamp …show more content…

These soils are not as developed as other soil orders. Some soils that are categorized within Inceptisols that are common to this area are: Commerce, Mhoon, and Sharky. Commerce soils are found on the levee, composed of sand and silt, and are well-drained. Mhoon soils are found on the lower levee, composed of silty clay, and are poorly drained. Sharky soils are found in the backswamps, are very high in clay, and are poorly drained. However, there is a small portion of the western part of the parish that is of the Alfisol soil order. Alfisols are more developed than Inceptisols in such a way that there are more horizon distinctions that are visible. In the subsoil, there is an accumulation of clay and a dense layer which prevents a lot of leaching of materials from the surface. These soils tend to have the presence of aluminum and iron oxides throughout the soil profile. All the soils that are in this region each support different types of …show more content…

The Bottomland Hardwoods and Cypress Region consists of backswamps and natural levees with bald cypress, tupelo-gum, swamp oak, and willow species. However, a small section of the parish on the western most part is Upland Hardwoods and Prairie. The Upland Hardwoods Region are majority oak, hickory, gum, magnolia, dogwood, and holly species. The Prairie consists of grasslands and gallery forests (i.e. oak, sweetgum, and hickory species) which used to be very plentiful before a lot of the land was converted to agriculture lands. This decline may also be due to a claypan layer in the subsoil which would restrict root penetration and limit tree

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