3/5/2015 1 Do you know the answers? What large landform in the western United States was formed by the movement of water over millions of years? Why do the pyramids in Egypt look like this? The Grand Canyon was formed by the Colorado River Weathering due to sand and acid rain Agenda 03 – 04 MAR 15 1. Quiz Review (I have – Who has?) 2. Vocabulary Quiz 3. Weathering and Erosion Notes 4. Weathering Lab
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Plant roots extend into fractures and begin to grow which causes the fracture to expand. Continued growth and expansion can break the rock!
Friction and
Repeated Impact
Rocks continually scrape or bump into other rocks, breaking smaller pieces off. These smaller pieces continue to bump and scrape against other rocks, eventually wearing away completely.
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Burrowing of Animals
Temperature
Changes
Heating causes rocks to expand. Cooling causes rocks to contract (shrink). When this happens unevenly, rocks can break. Heating can be caused by sunlight or fires!
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Chemical Weathering
The process that breaks down rock through
chemical changes.
Types:
Dissolving by water
Oxygen (Oxidation)
Carbon dioxide
Living organisms (urine) or dead decomposing
Acid rain
Water Water weathers rock by dissolving it.
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Oxygen Oxygen combines with other elements to form new substances. For example, oxygen combines with iron in the presence of water. The product of this oxidation reaction is rust.
Carbon
Dioxide
Carbon dioxide (CO2) dissolves in rain water, forming carbonic acid. Carbonic acid can easily dissolve limestone and marble, causing significant weathering.
Lichens that grow on rocks produce weak acids that chemically weather rock. Decaying organisms can also produce acids (from bacteria) that are capable of weathering rock.
Acid Rain Compounds from burning coal, oil, and gas react chemically with water forming strong acids. Acid rain causes very rapid chemical weathering.