osion- due to rain drops and overland flow-vegetation reduces runoff and roots percolate waterafter streams form* laminar flow- particles travel in parallel layers, slow and smooth velocity* turbulent flow- swirls and eddies, high and complex velocity-bed and channel walls maintain laminar flow (frictional drag)Transport by Running WaterTypes of Stream Load* bed load- coarse particles that move along stream bed (up to 50% load) via-rolling or sliding-saltation-short intermittent jumps* suspended load- fine particles that move along surface-silt and clay* dissolved load- dissolved substances (underground seepage) (product of chemical weathering)* sediment size correllated to velocity of stream (greatest w/ steep slopes or basins)* alluvium- name for solid particles wherever they are droppeddownstream changes:* grain size decreases (opposite than expected)* composition/mineralogy of sediments (new rocks)* placer deposit- concentration of heavy minerals* sediment yield- amount of sediment eroded and transportedDeposits by Streams (alluvium)* point bars (see: meandering channel pattern)* floodplains (part of natural valley) and natural levees (low ridge of alluvium along side of channel) (see: frictional drag and turbulent flow)* terraces- remnant of abandoned floodplain* alluvial fans- fan-shaped alluvium deposits where a channel leaves a valley* deltas- stream flows into standing water (sharp velocity drop)-fan vs. braid deltas (shape determined by sedimentation/erosion balance)-foreset layer =* topset layers of deposition-topset layers between channels (distributaries)Drainage Systemsterminology* drainage basin- total area that contributes water* divide- line that separates adjacent basins* continental divide- basins drain to different oceans (follow techtonic allignment)-velocity- steep Andes, gradual Atlantic* stream order- system of numbering streams (first- order)drainage pattern development* rock type* rock structure* stream history...
