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Weathering of Rocks. By: Caitlin McGlynn , D avid Wilker , and Courtney O’Brien. What is weathering?. Weathering - Process which acts at the earth's surface to decompose and breakdown rocks Erosion - The physical movement of weathered rock from its original site
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Weathering of Rocks By: Caitlin McGlynn, David Wilker, and Courtney O’Brien
What is weathering? • Weathering - Process which acts at the earth's surface to decompose and breakdown rocks • Erosion - The physical movement of weathered rock from its original site • Primary agents are gravity, wind, water…
Types of Weathering • Mechanical or Physical - the breakdown of rock material into smaller pieces without changing the chemical composition • Chemical - the breakdown of rocks by chemical agents • Biological- when plant or animal life causes the breakdown of the rock
Mechanical Weathering • Expansion and Contraction - the thermal heating and cooling of rocks • Frost Action - Water freezes at night and expands because the solid occupies greater volume. Action wedges the rocks apart. • Exfoliation - process in which curved plates of rock are stripped from a larger rock mass. • Other types - Cracking of rocks by plant roots and burrowing animals.
Weathering of Rocks Depends on… • Rock Composition- Some rock types are more likely to resist weathering while others are more vulnerable to it • Rock Properties- Properties that make it easier for water to infiltrate a rock make it more vulnerable to weathering • Climate- Some weathering processes cannot occur in certain climate zones
Weathering Rates • Not all rocks weather at the same rate • Some rocks are harder than others • Ex: Quartz is more resistant to chemical and physical weathering • Results in cross-cutting
Sedimentary Rock Cycle • Deposition – when the sediment is deposited and left to settle • Lithification • Compaction - Squeezing out of water • Cementation - chemical cement is formed • Recrystallization - Growth of crystal in the sediment
Video • http://www.youtube.com/watch?v=lyysL02ZvQ8
Sources • http://www.youtube.com/watch?v=lyysL02ZvQ8 • http://www.mrsciguy.com/weathering.html • http://geology.csupomona.edu/drjessey/class/Gsc101/Weathering.html • http://www.reachoutmichigan.org/funexperiments/quick/academy/weatherexp.html • “The Good Earth: Introduction to Earth Science” (pg 255-258)