weathering: disintegration of rocks in situ physical weathering size and shape of rocks altered but...
TRANSCRIPT
![Page 1: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/1.jpg)
Weathering: Types and Rate of Weathering
![Page 2: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/2.jpg)
Weathering: Disintegration of rocks
in situPhysical
Weathering Size and shape of rocks
altered but not the chemical composition
Angular and coarse end-products
Some involvement of water in the processes (e.g. freeze-thaw and salt crystal growth)
Effective in extreme climate conditions
Chemical Weathering
Physical structure and chemical composition of rocks altered
Finer end-products (e.g. clay and sand)
Water (rainwater, seawater) is important as the main solvent in all processes
Effective in vegetated areas and hot and wet climate
![Page 3: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/3.jpg)
Chemical Weathering
Hydrolysis
Carbonation
Oxidation
Solution
![Page 4: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/4.jpg)
Karst Landscape
![Page 5: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/5.jpg)
Insolation Weathering
![Page 6: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/6.jpg)
Pressure Release
![Page 7: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/7.jpg)
Salt Crystal Growth
![Page 8: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/8.jpg)
Freeze-Thaw Action/ Frost Shattering
![Page 9: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/9.jpg)
![Page 10: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/10.jpg)
Factors affecting type and rate of weathering
![Page 11: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/11.jpg)
Factor 1: Rock Hardness
Rock Hardness- dependent on minerals that form rocks and how minerals are cemented together
Igneous stronger than Sedimentary rocks. Why?
Least important factor since all rocks ultimately experience weathering once they are exposed to weathering agents
![Page 12: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/12.jpg)
Factor 2: Mineral composition
Influence rock resistance to chemical weathering
Weaker minerals: calcium carbonate, olivine and pyroxene
Stronger minerals: quartz
Influence also physical weathering like insolation weathering because of differences in coefficient of expansion and contraction of minerals
![Page 13: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/13.jpg)
Factor 3: Grain size of rocks
Coarse-grained rocks weathered down faster than fine-grained rocks
When minerals susceptible to changes are altered (e.g. feldspar), larger gaps are formed, weakened structure, larger gap provides bigger surface area for further chemical attack
![Page 14: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/14.jpg)
Factor 4: Lines of Weakness of rocks
Lines of weakness (e.g. cracks, joints, bedding planes) found in rocks make them more susceptible to both physical and chemical weathering. How?
The more well-jointed the rock is, the faster the rate of physical, chemical and even biological weathering
![Page 15: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/15.jpg)
![Page 16: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/16.jpg)
Factor 5: Relief
On flat land, soil and weathered materials can retain water which seeps through them and acts on the underlying rocks chemically
On slopes, mass movements, like landslides and slumping, expose more underlying rocks for physical weathering.
Chemical weathering less effective on steep slopes as water flows away
![Page 17: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/17.jpg)
Factor 6: Vegetation cover
Vegetation cover can retain rainwater and keeps underlying rocks moist for chemical weathering to take place
Biological weathering common too
![Page 18: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/18.jpg)
Factor 7: Human activities
How do human activities contribute to weathering?
![Page 19: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/19.jpg)
Weathering regions of the world in relation to mean annual
temperature and precipitation (Peltier,1950)
![Page 20: Weathering: Disintegration of rocks in situ Physical Weathering Size and shape of rocks altered but not the chemical composition Angular and coarse](https://reader035.vdocuments.net/reader035/viewer/2022062519/5697bfdd1a28abf838cb1ade/html5/thumbnails/20.jpg)