1. Physical and Chemical Weathering pg 70-79
Objectives: Fill out weathering graphic organizer
Identify examples of physical and chemical weathering

2. Essential Question
How do chemical and physical weathering processes change the surface of the Earth?
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7. What is weathering?
Weathering is the breakdown of rock material by physical and chemical processes

8. What causes physical weathering?
Physical weathering is the process by which rock is broken down into smaller pieces by physical changes WITHOUT changing its chemical composition
Temperature changes, plants and animals, water, wind, gravity are all things that can physically weather a rock

9. What causes physical weathering?
Example: Ice Wedging
Water collects in the cracks of rocks. It then freezes and expands. This causes the crack to widen. Water will then melt and freeze again at another time, causing the crack to widen even more. Eventually, cracks can cause the rocks to split apart

10. How can a temperature change in rocks and water cause weathering?

11. What causes physical weathering?
Example: Abrasion
When rocks are broken down and worn away by other rocks
Ex: Sand in the wind can wear away at rock surfaces
Ex: Rocks tumbling over one another in a river or in a rockslide
Example: Plants and Animals
Animals can move soil and allow new rocks to be exposed to the surface
Plant roots grow in small cracks and break it apart

12. What causes physical weathering?

14. How does the biosphere contribute to the weathering of rocks?

15. What causes chemical weathering?
Chemical weathering is the breakdown of rocks by chemical reactions; this changes the chemical composition of the rock
Oxygen in the air or acids

16. What causes chemical weathering?
Example: Oxidation
When oxygen reacts with the compounds that make up the rock, usually causes a color change
Ex: Reddish orange rocks of AZ – caused by iron in rocks combining with oxygen in water  RUST!

17. What causes chemical weathering?
Example: Acid precipitation
Acids in the atmosphere combine with water in the rain. Falls to earth and is able to weather rocks faster.
Example: Acids in groundwater
Groundwater moves and the acids in it can cause cave systems to be carved out over time

18. How can groundwater cause weathering?
How does acid precipitation cause weathering?

19. Real World Application
Cleopatra’s Needle
Carved around 1450BC
Distinct heiroglyphs
Stayed in the hot, dry climate of Egypt
Moved to New York City in 1800
Hieroglyphs began to fade in the wet, variable climate of NYC
Is this Physical or Chemical weathering?

20. Real World Application
Cleopatra’s Needle
Carved around 1450BC
Distinct heiroglyphs
Stayed in the hot, dry climate of Egypt
Moved to New York City in 1800
Hieroglyphs began to fade in the wet, variable climate of NYC
Is this Physical or Chemical weathering?