BIOL 4308 Test 1 material 9-9-10

BIOL 4308 Test 1 material 9-9-10 - Biol 4308 LOUISIANA...

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Biol 4308 LOUISIANA COASTAL LAND LOSS PROCESSES 1. Deltaic Geology and the Delta Cycle The Delta Cycle Miss. River outflow delta shaped LA coastline. Subdeltas (small deltas off of the main one, such as the birdfoot) occur after large deltas have been formed As deltas deteriorate, biological diversity increases while delta lobe sizes decrease. Progradation of the Atchafalaya Delta Atchafalaya delta (Morgan City) is creating more coastal land, do to deposition 1. Initial progradation 2. Enlargement by further progradation 3. Distributary (Delta) abandonment and movement of river to another location 4. Repetition of cycle – similar to barrier island formation Land Subsidence Land subsides as sea levels rise. The subsiding land is inshore, such as underneath lakes and bays. Marsh Development 1. Fresh marsh with silt clay floor 2. Natural levees and channel(s) form (similar to the spillway) due to the sinking of marshes. 3. Swamp/Brackish marsh is trapped in front of the levee facing the gulf, and eventually develops into a full saline/brackish marsh due to entrapment between the natural levees and gulf. 4. Bays and sounds form – original silt floor is now fully subsided, and marshes and levees are beginning to partially destruct and erode. Inundation – Deposition of fresh H 0 from one habitat to another. Can occur between most habitats depositing freshwater into open water (open water/salt marsh are the saltiest (hypertonic)). Salination – Deposition of salt from marsh habitats to one another or to swamps and hardwood areas. Deltaic Barrier Island Evolution 1. Abandonment of delta – causes erosional headland with island barriers 2. Submergence of land – creates barrier island arc separated from mainland 3. Submergence of more land – creates shoals 4. Reoccupation of delta – active delta begins to deposit land on top of shoals, and a new delta forms (no more barrier islands). -- combination of primary and secondary coastal development
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This note was uploaded on 10/12/2010 for the course BIOL 1208 taught by Professor Crowe during the Spring '10 term at Louisiana College.

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BIOL 4308 Test 1 material 9-9-10 - Biol 4308 LOUISIANA...

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