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? Water carries sediments in the following ways: Solution – - Suspension – - Rolling or bouncing along the streambed. Floating – -

Streams act as conveyor belts River Floor 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

Low Kinetic & Potential Energy Stream Side View Greatest Potential Energy = Stored Energy Greatest Kinetic Energy = Energy of Motion Lake Most Erosion Low Kinetic & Potential Energy Most Deposition Ocean Dynamic Equilibrium Rate of Erosion = -

Changing Stream Velocity: B. -- Stream velocity determines size of sediment carried. ESRT pg 6  Take out your ESRT!

Streambed --

Stream bank --

Region of maximum stream velocity changes when streams bend or turn. Region of maximum velocity shifts to -- Region of minimum velocity shifts to --

Since the region of maximum stream velocity is at the outside of the curves, streambeds are more eroded at the outside of curves. A A’ Streambed B’ B Streambed C C’ Stream bed Stream A A’ C’ C B B’

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?

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Topic: Life Cycle of a Stream

Youthful Stream Lake (Source of Water) Waterfall Steep Slope Rapid Flow Rapids

This forms V-shaped valleys.

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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 Very broad, flat valley (flood plain) filled with fine sediments - alluvium Slow speed Almost flat slope Very little erosion Oxbow lake Wide meanders Wide flood plain

Meander – --

Oxbow lake – --

Rejuvenation – a stream may be brought back to a youthful stage of development at any time by uplifting the land. (ex. Grand Canyon)

Name the part of the stream’s life cycle in the picture

What shape do stream valleys make? FQ: What shape do stream valleys make? ---