Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chemical & Mechanical Weathering 1. Investigation • Chemical Weathering (4 types) • Mechanical Weathering (5 types) 2. Complete pages 73 about weathering. Resources: readings, “How to make Mudpie” movie, textbook (orange) p 295-296, website: http:facweb.bhc.edu/academics/science/harwood r/geol101/study/weather.htm Mechanical & Chemical Weathering 1. What are the four types of chemical weathering? Oxidation, Carbonation, Acids, Hydration 2. What are the five types of mechanical weathering? Root action, Thermal expansion, Hydraulic Action, Organic Activity, Gravity Chemical Weathering Definition: the process that breaks down rock through chemical changes Chemical Weathering 1. Oxidation • Combines oxygen with another substance in the rock • Usually changes color of rock 2. Carbonation • Happens in rocks that contain calcium carbonate (limestone) • Speeds up as the temperature decreases 3. Acid Rain • Formed by sulfur and nitrogen compounds • Will cause rocks to fall apart 4. Hydration • Incorporation of H+ and OH- ions from H2O • Causes an increase in volume • Adds stress within the rock Mechanical Weathering Definition: the process that breaks down rock physically Mechanical Weathering 1. Root Action • As roots grow, they break rocks apart 2. Thermal Expansion • Temperature changes: Rocks heat up in the day and as the temperature drops greatly at night, the rocks can flake easily (defoliate) • Common in deserts 2. Thermal Expansion (continued) • Freeze/thaw will also deposit water in cracks • When water freezes, the ice pushes outward causing pieces of the rock to break off 3. Hydraulic Action • Water (usually from powerful waves) rushes into cracks in rocks • A tiny bit of air is compressed at the crevice of the crack • When water recedes, the air is forcefully released taking away fragments of rock with it 4. Organic Activity • Mosses and lichens attach to rocks (note: lichens cause physical and chemical breakdown of the rock) 4. Organic Activity (continued) • Plant roots exert physical pressure on rock cracks (note: plants form an acid on the rocks that further break down the rock) 5. Gravity • Large rocks often fall from mountainsides and as they hit bottom they break into smaller pieces