As the gradient of a river becomes less,

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As the gradient of a river becomes less, The
river enters the mature stage of its life
At this stage the river show some characteristics
of youth, and some of old age
Yellowstone River
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Sand bar
The river may start to braid and deposit sediment
in the mature stage
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As the river becomes old, it develops meanders
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Large meander
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Old meandering stream in Colorado
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Erosion here
As the stream curves It slows on the inside And
speeds up on the outside,
Deposition here
As a result
Sand bar
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Chalkboard diagram
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High velocity large sediment carried
Low velocity larger sediment deposited
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Red line shows the fastest velocity
Deposition here
Erosion here
Where the stream runs straight, the fastest
velocity is in the center just below the surface
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The velocity of a stream or river determines The
size of the sediment it can carry
Example What velocity would be required to
transport a small cobble (6.4 cm.) ?
The following chart shows how to get the answer
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Intersects Graph here
Answer 175cm/sec
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What is the smallest size particles that could
be transported by a stream with a velocity of 400
cm/sec?
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Answer boulders
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Particles that are 1.5 cm. In diameter would be
which type of particle?
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Answer pebbles
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In the process an oxbow lake is formed
Streams that develop very sharp meanders
may actually undergo cutoff a new channel is
formed as shown
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Oxbow lake
New channel
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Sand bar
Oxbow lake
Flood plane
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Profile of an old age river
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River
Flood plain
Natural levee
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Flood plain
river
Man made levee
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When old age rivers reach the ocean or a lake, a
delta is formed as the river drops most of its
remaining sediment
Young delta
Mature delta
Old delta
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New Orleans
river
Mississippi delta as seen from space shuttle
Gulf of Mexico
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Nile River Delta
Nile River
Mediterranean Sea