1. Rocks and Weathering Chapter 6 Section 1

2. Weathering and Erosion  Weathering is the process that breaks down rock and other substances at Earth’s surface.  Erosion is the removal of rock particles by wind, water, ice, or gravity  Weathering and erosion work together continuously to wear down and carry away the rocks at Earth’s surface.  Bicycles rusting, paint peeling, sidewalks cracking, and potholes are results of weathering

3. Types of weathering  Mechanical Weathering -- when rock is physically broken into smaller pieces.  Causes of mechanical weathering include freezing and thawing, release of pressure, plant growth, actions of animals, and abrasion.

4. Types of Weathering  Chemical Weathering -- the process that breaks down rock through chemical changes.  Chemical weathering can produce new minerals as it breaks down rock  Chemical weathering creates holes or soft spots so that rocks break apart more easily

5. Causes of Chemical Weathering  Water -- weathers by dissolving; most common  Oxygen -- weathers by oxidation, causing rust. Only occurs in rocks containing iron  Carbon Dioxide -- CO 2 in rain water forms carbonic acid. Carbonic acid easily weathers softer rocks  Living Organisms -- as plants grow, roots and stems push into cracks in rock. These roots and stems form weak acids that can dissolve the rock  Acid Rain -- Sulfur, carbon, and nitrogen mix with water vapor in the air causing acid rain. Acid rain causes very fast chemical weathering.