1. Science Starter Pick up a post-it note at the front desk and answer the following questions… What is weathering? What is erosion? Place your post-it note on the white board.

2. Mechanical Weathering Mechanical Weathering physically breaks down rock into smaller pieces Mechanical weathering is a slow process and breaks down through natural agents – Freezing and thawing, release of pressure, plant growth, actions of animals, and abrasion

3. Mechanical Weathering Agents Abrasion – grinding of rock by rock particles carried away by ice, wind, gravity, or human activity. Frost wedging – wedges of ice in rocks expands in cracks – Repeated freezing and thawing, the cracks expand until pieces of rock break off

4. Chemical Weathering Chemical Weathering breaks down rock through chemical changes Agents of chemical weathering include the following: – Water, oxygen, carbon dioxide, living organisms, and acid rain

5. Chemical Weathering Agents Oxygen – Oxidation: iron combines with oxygen in the presence of water -Rusting occurs during this process Carbon Dioxide - gas that dissolves in water creates carbonic acid and easily wears away rocks (limestone) Living Organisms – plant’s produce weak acids Acid Rain – Acid mix combines with raindrops