Weathering, Erosion, and Deposition Notes

Weathering – the process by which rocks are broken down into sediments slowly over time Mechanical weathering breaks down rocks into smaller pieces through physical processes changes the shape and size of a rock, but it doesn't change the rock's chemical composition Wind*, water*, living things, changing temperatures all cause weathering. Chemical weathering breaks down rocks through chemical processes changes the rocks' chemical composition

Erosion moves sediments to other locations Flowing water* can carry rocks, sediments, and soil downstream Wind* is another agent of erosion Animals are agents of erosion as they burrow into the ground, moving sediments out of their way Another erosional agent is gravity, which constantly pulls rocks downhill as they weather

Deposition When sediments stop moving and settle where the erosional agents have carried them (from the word “deposit”) When sediments are eroded by wind, flowing water, ice, or gravity, they are generally deposited in horizontal layers

Human activities cause weathering and erosion: Digging and moving soil during construction Cutting down trees – soil is less stable and more vulnerable to erosion Pollution – adds more chemicals to the air  acid rain