Mechanical Weathering What is weathering? Mechanical and chemical processes that change objects on Earth’s surface over time. Weathering occurs slowly but the rate of weathering varies depending on the weathering agent. Mechanical Weathering When physical processes naturally break rock into smaller pieces over time. Chemical Weathering changes the object chemically over time. Chemical reactions occur during chemical weathering.

Examples of Mechanical Weathering Ice Wedging Abrasion Plants animals

Examples of chemical weathering Acidification Oxidation

What is the difference between weathering and erosion? Erosion is the movement of Earth’s sediment from one location to another. The effects of weathering are often followed by erosion. Which example below is weathering and erosion? The constant pounding of waves on the shoreline causing rock to turn to sand.______________ The wind blowing the sand to make dunes._____

Do Now: Write mechanical or chemical weathering next to each example. Wave action against the shore.__________ A rusty nail__________________________ Cement cracks in a driveway.__________ Pot holes on a highway._______________ Plant roots growing into a driveway.______ Acidic rain causing pitting of a metal lamp post.__________________

Do Now: How do you think weathering and erosion will shape the coastline of Long Island in the next 100 years?

What is Deposition? Deposition is the laying down(setteling) of eroded sediment. Often happens at river basins, mountain valleys, ocean bottoms and along coasts. How are erosion and deposition related? What factors effect the rate of erosion?

Sediment sorting by size Poorly sorted sediment has a wide range of sizes Moderately sorted sediment has a small range of sizes Well sorted sediment has particles all the same size How would you classify the sediment below?

Do Now: Observe the diagram of sediment below. Label each as well sorted, moderately sorted and poorly sorted. Explain why you believe each is grouped as such. Which best characterizes the sand at Smith Point?