1. Science 6 Study Pack #8

2. Today’s Goals…  I can explain what weathering is.  I can identify different causes of weathering.

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. Weathering  A process that breaks rocks into smaller pieces  Mechanical  Chemical

5. 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

6. 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

7. 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

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

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

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

11. Assignment  Frayer Model for Vocabulary  Weathering  Definition – In your own words  Characteristics – You may want to include types here  Examples  Nonexamples