Presentation on theme: "Topic: Erosion & Running Water * Earth’s main agent of natural erosion."— Presentation transcript:
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 – -
River Floor Flow of the River Cobbles & Pebbles Move by sliding, rolling along the river floor Slower than the water flow Sand Bounces along river floor Slower than the water flow Colloids (Silt & Clay) & Dissolved Ions Carried in suspension Same speed as water Streams act as conveyor belts
Lake Ocean Stream Side View Greatest Potential Energy = Stored Energy Greatest Kinetic Energy = Energy of Motion Low Kinetic & Potential Energy Most Erosion Most Deposition Dynamic Equilibrium Rate of Erosion = -
Changing Stream Velocity: A. -- B. -- Stream velocity determines size of sediment carried. ESRT pg 6 Take out your ESRT!
Region of maximum stream velocity changes when streams bend or turn. Stream 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. Stream A A’ B B’ C’ C A A’ Streambed B’ B Streambed C C’ Stream bed
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?
Topic: Life Cycle of a Stream
Youthful Stream Steep Slope Rapid Flow Lake (Source of Water) Rapids Waterfall
This forms V-shaped valleys.
Middle Age Velocity decreases due to decrease in slope Downcutting slows due to velocity decrease Valley walls become wider Begins to meander
Old Age Stream Slow speed Almost flat slope Very little erosion Wide meanders Oxbow lake Wide flood plain Very broad, flat valley (flood plain) filled with fine sediments - alluvium
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