Weathering and Erosion Weathering Breakdown of rock at or near the earths surface 2 types of weathering Mechanical Chemical Mechanical Weathering: no change in chemical composition--just disintegration into smaller pieces Mechanical Weathering Types of Mechanical weatheringTypes of Mechanical weathering Frost heaving and Frost wedging Plant roots Frost Wedging: water freezes in a crack and breaks it apart (MOST COMMON TYPES OF MECHANICAL) Frost Heaving Plant Roots Chemical Weathering: changes or alters as a result of chemical reactions CaCO 3 +CO 2 +H 2 O ---> Ca HCO 3- Chemical Weathering The agents of chemical weatheringThe agents of chemical weathering Water Acid Rain Water Acid Rain Compounds from burning coal, oil and gas react with water forming acids.Compounds from burning coal, oil and gas react with water forming acids. Acid rain has eaten away this limestone statue. Erosion The movement of weathered materials by water, wind, or glaciers Water Erosion forms the largest canyons and the deepest valleys Wind Erosion Picks up small particles. Usually in areas of little water or little vegetation Wind Erosion Erosion by Glaciers that were formed over many years as ice and snow are compressed Glaciers can create lakes as they melt