1. What are the two main types of weathering? Warmup 1. What are the two main types of weathering?

Weathering and Erosion Weathering breaks down the rocks, erosion moves the particles, and deposition drops the sediments in another location. Badlands National Park, South Dakota

Arches National Park, Utah Weathering The process in which water, ice, and heat break down rock into smaller pieces, called sediments. Arches National Park, Utah

Mechanical (physical) Weathering Physical Weathering – the breakdown of rocks and minerals into smaller pieces without a change in chemical composition. Frost Wedging Root/Plant Wedging Abrasion

Mechanical (physical) Weathering Frost Wedging - alternate freezing & thawing of water that causes rock to break or crack Root/plant wedging – plant roots growing into existing joints and fractures.

Abrasion- when rocks rub against each other

Badlands National Park, South Dakota Chemical Weathering The breakdown of rocks and minerals into smaller pieces by chemical action. Badlands National Park, South Dakota 7 Colors Hill, Argentina

Badlands National Park, South Dakota Chemical Weathering Oxidation- when oxygen unites chemically with a mineral. Ex. Rust (iron oxide) Badlands National Park, South Dakota 7 Colors Hill, Argentina

Hydration- when water unites chemically with minerals.

Mechanical (physical) Weathering Chemical weathering Pressure/stress release Organic acid (moss, lichen, or pine needles) Abrasion by wind, water, or human activity Hydrolysis (reacting with water) Gravity (mass wasting) Acid precipitation Exfoliation Hydration (dissolving in water) Ice wedging Oxidation (metal and oxygen) Biological (animal burrows, roots)

Rates of Weathering Surface area - If particle size goes down then weathering rate goes up (more surface area exposed). Weathering eats away sharp edges first (makes things round)

You saw this last week when talking about clasts (the grains in a sedimentary rock)

Rates of Weathering Climate- the average weather of a location over time (precipitation and temperature)

Rock type and composition Rates of Weathering Rock type and composition Different minerals weather at different rates. Hard rocks weather slowly Soft rocks weather quickly

Erosion and Deposition Erosion – the process where sediments are transported by: Wind Gravity Glaciers Running water Living Things Deposition –The process in which sediment is dropped and comes to rest

Erosion Wind Erosion– hot and dry areas especially (little ground cover to stop erosion). Glacial Erosion– scrape and gouge, carry debris

Erosion Rill erosion – caused when water runoff is heavy (after rainfall) Gully Erosion – removal of large amounts of soil by heavy rainfall

Earth Science Work on poster Work on rock cycle study guide Work on cheat sheet for Friday’s QUIZ!