Gradient is so steep that water cascades or free falls o Waterfalls scours a

Gradient is so steep that water cascades or free

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Gradient is so steep that water cascades or free falls o Waterfalls scours a deep plunge pool o Basal erosion leads to collapse of overlying rocks o Waterfalls are temporary base levels Aluvian Fans o Build at canyon mouths o Sediments drops out as water spreads out from mouth—coarsest first, finer carried further o Creates fan shape Braided streams o Trunk stream consists of many interfingering channels o Sediment load is very high, channel is very low Abundant coarse sediment moves during floods Sediment is deposited, chokes channel in normal flow Weaving channels create ephemeral sand and gravel bars Meandering Streams o Have sinous, looping curves (meanders) o Form where: The stream gradient is low The substrate is soft and easily eroded The stream exists within a broad floodplain o Fast par of current swings back and forth—momentum increases during flood, erodes outside bank o Curve migrate downstream during flood events Deltas: o Delta forms when a stream enters standing water Stream divides into a fan of distributaries Velocity slows; sediment drops out o Delta morphology is a dynamic balance of sediment load, waves and storms, tides and slumping Birds foot Arc-like Triangle shaped Atmospheric CO 2 since industrialization
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Human Impact on the earth system o Exponential pop. Growth through: Industry, agriculture, tech and medicine Fueled by a suitable supply of natural resources Recent global warming—human greenhouse gas additions alter climate o CO2 in the atmosphere has steadily climbed since the industrial revolution began Ice core data show atmospheric CO2 in 1750 was ~280ppm In 1958, CO2 was ~315ppm 210, CO2 was ~390ppm Today, ~400pm, increasing at >2 PPM/yr o Human additions of CO2 and CH4 exceed natural removals Fossil fuel combustion (CO2) Rice-paddy decay (CH4) Cow flatulence (CH4) o Observations: Larsen B (ice chelf) break up Summer melt line indicates that melting of Greenland ice sheet is accelerating Valley glaciers worldwide are retreating Aric Ocean Sea-ice is reduced Rise in sea level (~3.2mm/yr) Warming will accelerate by thermal expansion of seawater and melting polar ice o Predict climate changes: 2050—T will increase by 1.5 degrees to 2.0 degrees C 2150—T could be 5 degree to 11 degrees warmer than present
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