GEOG 2300 1st Edition Lecture 30Outline of Last Lecture I. Water UseII. Fluvial ProcessesIII. WeatheringIV. SlopesOutline of Current Lecture I. Stream ProcessesII. Parts of a StreamIII. WetlandsCurrent LectureI. Stream Processes A. Processes of erosion, transport, and deposition; three phases of same activityB. Erosion: Hydraulic action: water itself dislodges material, Abrasion: material carried by the river erodes the valley, Corrosion: rocks and minerals dissolved by water (least important)C. Transportation: Traction: sliding or rolling of particles, Saltation: water lifts particles off river bed – these particles bounce along, Suspension: fine sediment (clay and silt) suspended in the water, Solution: material dissolved in stream waterD. Streams carry loads in different ways, bed load moves by sliding or rollingII. Parts of a StreamA. Originally streams begin as a succession of lakes, falls, and rapids; eventually the stream erodes to create a graded profileB. First indication of gradation is the development of a flood plain; widens over time creating a flat valley floorC. River meanders back and forth (alluvial meanders), on the inside of each bend: deposition (point bar), on the outside of each bend: erosion (cut bank)D. Oxbow lake: lake that forms from the cut off bend of a river, when the alluvialmeanders of a graded stream cut themselves offE. Flood plain: alluvial streams migrate back and forth across a valley form, creating a flat plain, terraces: at the margin of the flood plainThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.F. Entrenched meanders: where uplift elevates a floodplain, a river will begin to cut down, they do not move around like shallow meanders on a flat floodplain, however they may cut back to produce cutoff lakesG. Thick floodplain accumulates which is prone to overbank floodingH. Waterfalls: an indication of an ungraded river profile, rare on major rivers, if there are waterfalls on major rivers – results of faulting (Victoria Falls), also created by glacial activity disrupting drainage patterns (Niagara Falls)I. Deposition occurs on the inside of the bend in a graded stream and erosion occurs on the outside. III. WetlandsA. Wetlands: saturated at least some of the time so they can have low oxygen conditions (slows decomposition)B. Have high nutrient content, productivity, and biodiversityC. Wetlands can act as filters for pollutantsD. Marshes: are fresh, brackish, or saline with low herbaceous vegetationE. Swamps: are wetlands with permanent, shallow water and woody vegetationF. Estuaries: where freshwater and saltwater meet, highly variable environment, many fishes and shellfish spend larval stages here, salinity and temperature and light penetration rapidly change, salt marshes and mangrove forestsG. Bogs: acidic freshwater with few nutrients composed largely of sphagnum (peat) moss or lichens, fed by rainwaterH. Fens: basic freshwater fed by groundwaterI. Vernal pools: seasonal wetlands that often act as breeding grounds for specialized animalsJ. Constructed wetlands: designed to absorb flash floods, clean the water, provide habitat, or serve some other
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