1. Weathering and Erosion

2. The Changing Earth
The earth is changing everyday, especially the Geology, we call this the process of weathering
Weathering- the breakdown of materials physically or chemically

3. Two Types
Mechanical
Chemical

4. Mechanical Weathering
Physically breaking down a rock or mineral into smaller pieces without changing the composition of the material

5. Factors that affect Mechanical Weathering
Temperature
Pressure

6. Temperature When a rock becomes cold, it becomes more brittle.
Water can seep into the cracks freeze and expand
This causes the rock to fracture even more and continue to crack
This is know as frost wedging

8. Pressure
When something is squeezed it is under stress which can cause it to crack
When a load is reduced off of bedrock, it is able to expand causing long curved cracks. These are known as Joints

10. Exfoliation- the process in which the outer layer of rock are stripped away
Similar to an onion being peeled

12. Chemical Weathering
Weathering that causes a change in the composition of the rock or mineral
Agents of Chemical Weathering
Water
Oxygen
Carbon dioxide
Acids
Temperature

13. Water
Water is important in chemical weathering because it can dissolve many kinds of minerals and rocks
When water acts with something else in a chemical reaction, it is known as hydrolysis

14. Oxygen
Oxygen can also combine with other substances during a chemical reaction
This is known as oxidation
Rust

15. Carbon Dioxide When CO2 mixes with water it forms a weak carbonic acid
This falls to the earth as precipiation
Materials most affected
Calcite
Limestone
Marble

17. Acid Precipitation
When acid precipitation reacts with rocks and minerals, it will cause it to be broken down and weathered away

18. What affects weathering
Climate
Rock type and Composition
Surface Area
Topography
Gravity

19. Erosion
The process in which sediments are broken down and then transported to another location
The “dropping” of these sediments is known as deposition

20. Erosion by gravity Gravity is needed for many erosional agents
Without gravity streams would not flow and glaciers would not move
Debris flows/landslides

22. Erosion by running water
Able to move large sized particles
Continuous flow due to the water cycle
High velocities due to steepness of slopes

24. Glacial Erosion Glaciers act as giant graters on the Earth’s crust
As they travel, they pick up and scrape numerous rocks and other geologic features

26. Wind Erosion We call these Aeolian process
Wind picks up sediments and blows them around hitting rocks and minerals
Mother nature’s sand blaster