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Topic: Erosion & Running Water. * Earth’s main agent of natural erosion. What is erosion?. Erosion is -. Agents of Erosion. Agents of erosion include -- Running water is the big Kahuna of all erosional agents. . How does water carry the sediments?.
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Topic: Erosion & Running Water * Earth’s main agent of natural erosion
What is erosion? • Erosion is -
Agents of Erosion • Agents of erosion include-- • Running water is thebigKahunaofallerosional agents.
How does water carry the sediments? • Water carries sediments in the following ways: • Solution –- • Suspension –- • Rolling or bouncing along the streambed. • Floating –-
River Floor Streams act as conveyor belts Flow of the River Cobbles & Pebbles Move by sliding, rolling along the river floor Slower than the water flow Colloids (Silt & Clay) & Dissolved Ions Carried in suspension Same speed as water Sand Bounces along river floor Slower than the water flow
Stream Side View Greatest Potential Energy = Stored Energy Dynamic Equilibrium Rate of Erosion = - Greatest Kinetic Energy = Energy of Motion Lake Most Erosion Low Kinetic & Potential Energy Most Deposition Ocean
Changing Stream Velocity: • A. -- • B. -- Stream velocity determines size of sediment carried. ESRT pg 6 Take out your ESRT!
Streambed --
Stream bank Stream bank --
Stream Region of maximum stream velocity changes when streams bend or turn. Region of maximum velocity shifts to -- Region of minimum velocity shifts to --
Streambed Stream bed Streambed Stream A B C C’ A’ B’ C C’ A B’ A’ B Since the region of maximum stream velocity is at the outside of the curves, streambeds are more eroded at the outside of curves.
What does erosion by rivers create? • Abraded sediments • --
FQ The stream’s velocity is 100 cm/sec, what size sediment(s) can the stream transport?
Youthful Stream Lake (Source of Water) Waterfall Rapids Steep Slope Rapid Flow
Middle Age Velocity decreases due to decrease in slope Begins to meander Downcutting slows due to velocity decrease Valley walls become wider
Old Age Stream Oxbow lake Wide meanders Wide flood plain Very broad, flat valley (flood plain) filled with fine sediments - alluvium Slow speed Almost flat slope Very little erosion
Rejuvenation – a stream may be brought back to a youthful stage of development at any time by uplifting the land. (ex. Grand Canyon)
FQ: What shape do stream valleys make? ---