1. Weathering

2. Weathering
Process that breaks down and changes rock at or near earth’s surface
Mechanical – rock is broken into smaller pieces by physical means
Chemical – rock undergoes changes due to a chemical change in composition

3. Mechanical Weathering
Two factors that are important to mechanical weathering are temperature and pressure.

4. Frost wedging

5. Exfoliation
bedrock is under pressure within the earth; as it is exposed to the surface the pressure is reduced and the rock expands and long curved cracks form; layers of rock are stripped away

7. Root action

8. Abrasion

9. Chemical Weathering
Chemical reactions take place that alter the rocks composition

10. Water: can dissolve many kinds of minerals and rock
Oxygen: can combine in chemical reactions with other substances – oxidation. Example: rust
Carbon dioxide combines with water in the atmosphere to create carbonic acid which dissolves rocks
Acid precipitation

11. Factors affecting the rate of weathering
Climate
Rock type and composition
Surface area
topography

12. Erosion
The transport of weathered material form one place to another

13. Forces that aid erosion
The force of gravity tends to pull materials downslope.

14. Running water
Running water has greater erosional power than wind and can move more material greater distances.
As the slope of the
land decreases, the water
slows and larger
particles are deposited.

16. Glacial erosion
Due to their high density glaciers carry huge rocks and piles of debris and scratch and grind over surfaces.
Erosion by abrasion

17. Wind erosion Wind picks up and moves fine particles
Prevalent in areas of low precipitation and high temperatures

18. Wind erosion

19. Mass Movements
The downslope movement of loose sediment and weathered rock due to gravity
Influenced by
weight of material
materials resistance to sliding/flowing
a trigger
water

20. Types of mass movement Creep – slow, steady downhill movement
Flows – materials flow as if thick liquid
Slides – rapid, downslope movement of a thin layer of material that separates from underlying bedrock
Slumps – mass of material rotates and slides along a curved surface
Avalanches – landslides that occur in mountainous areas with thick accumulations of snow
Rock falls – rocks break loose and fall downward

21. Good Catch
That's a Big Rock
Washington Mudslide
Glad I Wasn't Standing There
Even More Thankful I Wasn't Driving