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. breaking down rock into smaller pieces.
Weathering
breaking down rock into smaller pieces.
What is changing about the object?
More pieces = More surface area
As surface area increase the rate of weathering increases(direct relationship).

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

4. b) Frost Wedging
What happens to water
when it freezes?
water expands when it freezes
this creates pressure that cracks the rock

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

6. changes the rocks chemical composition to create a new material.
III. Chemical Weathering
changes the rocks chemical composition to create a new material.
- Water is the most important agent for chemical weather because most materials are soluble
(can be dissolved by water).

7. Which minerals will react with acid?
Acid Rain
- water combines with different elements to make acids, known as Hydrolysis.
- H2O + sulfur = sulfuric acid (acid rain)
Which minerals will react with acid?
acid rain damage on trees

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. IV. Rate of Weathering
Depends on…
a) Rock Composition. Some rocks are more resistant (stronger) to weathering because of their composition (minerals).
Granite
Limestone

11. In the diagram below, which letter rock is most resistant to weathering?
Hoodoo

12. More surface area = more places to weather
b) amount of surface area affects the amount of weathering
WHY?
More surface area = more places to weather

13. c) 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