L20 Sediments entering the ocean

L20 Sediments entering the ocean - Geol 107 L20 10/10/2011...

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Geol 107 L20 10/10/2011 1 Sediments entering the oceans Erosion Erosion is the process of removing unconsolidated Earth material and transporting it to other depositional sites (mainly the oceans) Transported by: Wind Water Ice Gravity Wind Erosion Dust storm off Sahara (MODIS 2004) Water Erosion Glacial Erosion Glacier moving down a glacial valley into a fjord, Glacier Bay, Alaska, USA. Note the median and lateral moraines and some icebergs in the bay. Gravity
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Geol 107 L20 10/10/2011 2 River supply to the ocean millions of tons per year Sediments entering the Oceans Sediments and Humans http://instaar.colorado.edu/deltaforce/startpages/margins.html Human activities have resulted in greater rates of erosion and more sediment carried by rivers…… yet Human activities result in 15-30% drop in sediment load carried by rivers to the ocean----why?
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Unformatted text preview: Geol 107 L20 10/10/2011 3 Sediment sediment gravel sand silt clay rock conglomerate sandstone shale siltstone Sediment Behavior Large (coarse) particles difficult to transport fall through water quickly Medium particle Medium particles easier to transport fall slower Small (fine) particles very easy to transport with current, never touch bottom fall very slowly It takes more energy to initiate entrainment than to transport particles Low pressure (= net lift) Lift on airfoil How clasts move High pressure Lift on clast prompts entrainment How clasts move once entrained Current Ripples One way versus Two Way Ripples on the seafloor Geol 107 L20 10/10/2011 4 Current Ripples One way versus Two Way Modern Ancient...
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L20 Sediments entering the ocean - Geol 107 L20 10/10/2011...

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