1. AIM: What is Weathering?
Do Now – Choose one of the following pictures and describe what is/has happened. A B c E F D

2. the breaking down of a rock into small pieces.
Weathering
the breaking down of a rock into small pieces.
What is changing about the object besides the shape?
As Surface area increases the amount of
Weathering increases

3. - changing the size and shape of the rock.
II. Mechanical (Physical) Weathering
- changing the size and shape of the rock.
Abrasion:
rocks hitting and smashing against each other.
What is making the rocks abrade in the stream?

4. III. Types of Mechanical Weathering
a) Frost Wedging
What happens to water
when it freezes?
water expands when it freezes
this creates pressure that cracks the rock

5. b) Biological Activity -
organisms(plants, animals and humans) break down rocks.

6. changing the rocks chemical composition. forms a new material.
IV. Chemical Weathering
changing the rocks chemical composition.
forms a new material.
* Water is the most important agent.*
Soluble:
a material that can be dissolved by water.
Acid Rain Damage

7. What mineral will all these acids react with?
V. Types of chemical weathering
Acid Rain
- water combines with different elements to make acids.
- this is known as Hydrolysis.
- H2O + sulfur = sulfuric acid (acid rain)
What mineral will all these acids react with?

8. Acid rain reacts with calcite and dolomite in the rocks (Limestone).
This dissolves the rock creating Karst Topography (caves), stalactites and stalagmites.

9. b) Oxidation
- Water and oxygen react with metal to create rust.

10. VI. Rate of Weathering A) Rock Characteristics:
- Mineral composition and solubility of the rock (the minerals that make the rock) determine the rate of weathering.
Granite
Limestone

11. - amount of surface area affects the amount of weathering
WHY?

12. - Some rocks are more resistant (harder) to weathering because of their composition (minerals).
In the diagram below, which letter rock is most resistant to weathering?
Hoodoo

13. B) Climate:
- Temperature and moisture help determine the type and amount of weathering.
- Chemical weathering is most effective
in areas with high temperatures (heat) and
abundant moisture (water).

14. Closure: In your Notes
Slate Headstone
Marble Headstone
Explain the difference in weathering of the two headstones (roughly the same age). What caused the difference in weathering?

15. Cleopatra’s Needle
2) Describe one factor that explains why Cleopatra’s needle changed after it was brought from Egypt to New York.
Egypt
Present Day -
Central Park