1. Today’s Agenda…Jan. 17th
Bellringer: What is weathering? Draw a picture of it! 
Review Mechanical Weathering
Finish Notes on Weathering
BrainPop on Weathering
Exit Slip

2. Weathering
Science 6
Study Pack #8

3. Weathering or Erosion? An old tombstone that is hard to read
A mountain after a landslide
Sand dunes
Rocks broken into tiny pieces
A crack in a sidewalk
A ditch where water has once flowed

4. Results from last week…
1st Period
3rd Period
7th Period

5. Weathering

6. Weathering

7. Weathering

8. Weathering

9. Weathering
A process that breaks down rocks
Mechanical
Chemical

10. Mechanical Weathering
Breaks rocks into smaller pieces WITHOUT changing them chemically
Smaller pieces are identical to the original rock
Two causes are:
Ice (or Frost) Wedging
Plants and Animals

11. Ice Wedging Water from rain or snow seeps into cracks in rocks
The water freezes and expands making the cracks open further until the rock breaks

12. Plants and Animals
Roots grow into cracks in rocks where water collects and force the rock apart
Some animals burrow through rocks and break them apart

13. Chemical Weathering
Occurs when the chemical composition of a rock changes
Causes are
Natural acids
Oxygen

14. Natural Acids
Carbonic acid (water and carbon dioxide) can dissolve certain rocks
Some plants produce acids that can affect rocks

15. Oxygen
When oxygen reacts with the iron in rocks it turns them orange or red