1. Erosion and Deposition
Agents, Forces, and Results

2. What Caused This?

3. What is Erosion?
Erosion – moving of rock material from one place to a new location
Three processes must take place:
detachment of particles
lifting them
transporting them
Agents of erosion:
flowing water
moving ice
waves
gravity
wind
Sand is composed of small pieces of rock that have been:
weathered from a rock
eroded
deposited somewhere else

4. What Is Wind Erosion? - Most effective in moving loose material
Wind – wears away rocks and is responsible for the creation of deserts such as the Sahara and the Gobi
- Most effective in moving loose material
Main effects:
Wind lifts small particles and moves them away.
Suspended particles may cause erosion on solid objects by rubbing.
Occurs in areas where there is not enough rainfall to support vegetation
What Is Wind Erosion?

5. What Is Water Erosion? Water – most influential force in erosion
Moves materials
Transports large objects with fast moving streams
Wears away rocks:
rivers
lakes
oceans

6. What Is Wave Erosion? Waves – relentless pounding Erodes:
softer/weaker rock first
harder/more resistant left behind
Can take over 100 years to erode a rock to sand
Energy of waves and chemicals contained in the water erode the rock off the coastline.

7. What Is Gravitational Erosion?
Mass Movement – downward movement of rock and sediments, due primarily to the force of gravity
Streams and glaciers
move material from higher  to lower  elevation
Occurs continuously on all slopes
slow moving and sudden movement until equilibrium is reached

8. What is Glacial Erosion?
Ice – moves and carries rocks, grinding the rocks beneath the glacier.

9. ç What is Deposition? Deposition means
laying down of sediment that has been transported
by a medium such as wind, water, or ice.

11. Deposition - Wind
Wind speed can be related to variations in heating and cooling.
Transportation of particles in wind:
Fine particles in suspension hundreds of km from its original source in the desert
Heavier material may be blown along the ground.
Material is deposited when the wind changes direction or loses its strength.

12. Deposition - Water
Running water enters a large and still body of water and its speed decreases
SPEED
As the speed of the water decreases, the water's ability to carry sediment also decreases.
Deposited in streams, rivers, and oceans:
Running water deposits sediments where the slowing water can no longer move them.
Largest particles are deposited near the coasts.

13. Deposition - Ice
Glacial flows of ice – become slower when the ice begins melting
– Deposits left by glaciers:
Outwashes are deposits similar to those left by rivers.
Large chunks of broken rock deposited at the base and sides of the glacier as it melts and recedes are called Moraines.
When the glacial ice melts, smaller material is carried by the rivers.

14. What’s the Difference?
WEATHERING – Think of weather wearing rock down.
EROSION – Think of a road and traveling.
DEPOSITION – Think of depositing money into a bank.