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Weathering and Erosion Weathering • The breakdown do the materials of Earth’s crust into smaller pieces. Physical Weathering • Process by which rocks are broken down into smaller pieces by external conditions. • Types of Physical weathering – Frost heaving and Frost wedging – Plant roots – Friction and impact – Burrowing of animals – Temperature changes Frost Wedging Frost Heaving Plant Roots Plants CAN PREVENT erosion Friction and Repeated Impact Burrowing of Animals Temperature Changes Chemical Weathering • The process that breaks down rock through chemical changes. • The agents of chemical weathering – Water – Oxygen – Carbon dioxide – Living organisms – Acid rain Water • Water weathers rock by dissolving it Oxygen • Iron combines with oxygen in the presence of water in a processes called oxidation • The product of oxidation is rust Carbon Dioxide • CO2 dissolves in rain water and creates carbonic acid • Carbonic acid easily weathers limestone and marble Living Organisms • Lichens that grow on rocks produce weak acids that chemically weather rock Acid Rain • Compounds from burning coal, oil and gas react chemically with water forming acids. • Acid rain causes very rapid chemical weathering Erosion • The process by which water, ice, wind or gravity moves fragments of rock and soil. Water Erosion • Rivers, streams, and runoff Water causes weathering What evidence of weathering do you see in this picture? Ice Erosion • Glaciers Ice Causes Erosion Glaciers can pick up and carry sediment that ranges in size from sand grains to boulders bigger than houses. Moving like a conveyor belt and a bulldozer, a single glacier can move millions of tons of material! Wind Erosion Wind causes weathering Why wasn’t this mass of land weathered away? What evidence of weathering do you see in this picture? Mass Movements • Landslides, mudslides, slump and creep landslide clip.mpeg Gravity causes erosion Creep, Slump, Landslides, Mudslides, and Avalanches. Slower Faster These are examples of mass movement landslide clip.mpeg (or called mass wasting) Deposition Rock particles that are picked up and transported during erosion will ultimately be deposited somewhere else Deposition is the process by which sediments (small particles of rock) are laid down in new locations. • Together, Erosion and Deposition build new landforms. Delta Where rivers meet the ocean is called the mouth of the river. Soil and dirt carried by these rivers is deposited at the mouth, and new land is formed. The new, soil-rich land is known as a Delta