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Stream Development. Stages of Stream Development. Young Streams:. -steep slope/gradient -high velocity -down cutting erosion. Narrow and V-Shaped Valley. Rapids. As a stream gets closer to its base level, it slow down and begins its “mature stream” phase.
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Young Streams: -steep slope/gradient -high velocity -down cutting erosion
As a stream gets closer to its base level,it slow down and begins its “mature stream” phase
This stream has cut downward over many years and is slowing… becoming more “mature”
Mature stream characteristics: • Decreasing gradient (slope) • Less energy for downward erosion • More erosion at sides of stream channel
Increased erosion at the sides of the stream begins which forms “meanders” or bends in a river.
Mature Stream meandering In this diagram, where will the fastest current be, the inside or outside of the channel?
Study this meander (bend) Why is the water deeper on the outside of the bend? Why is the water shallower on the inside of the bend?
http://www.cleo.net.uk/resources/displayframe.php?src=309/consultants_resources%2F_files%2Fmeander4.swfhttp://www.cleo.net.uk/resources/displayframe.php?src=309/consultants_resources%2F_files%2Fmeander4.swf
Over time, erosion and deposition cause increased... ? Meandering
Increased meandering can lead to the formation of “oxbow” lakes. Can you spot an oxbow lake in the picture below?
Stages of a typical oxbow lake formation due to erosion and deposition
Deposition • If velocity of a stream or river decreases, what will happen to the material load the stream carries? It can be deposited
Horizontal Sorting • Horizontal sorting- As water slows gradually, smaller and smaller particles drop out causing • Gradual decrease in velocity Sorting Animation McDougal Sorting Animation
Deposition Stream Deposition Occurs In Areas: • At widening rivers. Why? 2. On the inside of a curve of a meandering stream. 3. At the mouth of stream/river that flows into a larger body of water
Delta- fan shaped deposit of sediments at the mouth of a river
Alluvial fan = fan-shaped deposited at base of mountains composed mostly of sand and gravel.
Rejuvenation of the Colorado River • “Rejuvenation” • To make young again • Downcutting • Wearing away of a major streambed until it reaches its _____ ________