weathering and soils (ch.3): week 5, friday; september 26, 2014
TRANSCRIPT
- Slide 1
- Weathering and Soils (ch.3): Week 5, Friday; September 26, 2014
- Slide 2
- Kaolinite http://mineral.esci.umn.edu/node/1182 Illite http://sunbio.my/?page_id=121 Vermiculite http://www.vermiculite.org/what_is_vermiculite.php
- Slide 3
- Clay Minerals Building block: Si Tetrahedra SiO 4
- Slide 4
- Clay Minerals Building block: Al Octahedra Al(OH) 6
- Slide 5
- Clay Minerals SiSi O Al OH Octahedral Layer Tetrahedral Layer Dominantly formed by hydrolysis and hydration
- Slide 6
- Clay Minerals
- Slide 7
- http://faculty.yc.edu/ycfaculty/ags105/week08/soil_colloids/soil_colloids_print.html Scanning Electron Microscope (SEM) image of Kaolinite
- Slide 8
- http://greenfieldgeography.wikispaces.com/IGCSE+and+GCSE+Weathering Hydrolysis: H + replaces a cation in a mineral 4KAlSi 3 O 8 + 4H + + 2H 2 O 4K + + Al 4 Si 4 O 10 (OH) 8 + 8SiO 2 Weathering granite forms grus Potassium feldspar Kaolinite (clay) Formation of Clay Minerals via Weathering
- Slide 9
- Clay Minerals and Progressive Weathering O T T O T T Cations O T T O T T Weathering O T O T O O
- Slide 10
- Clay Minerals Why are clay minerals so important on Earths surface?
- Slide 11
- Clays exhibit shrink-swell behavior because of their ability to hold water Clay Function #1: They Hold Water!
- Slide 12
- Cation Exchange: Exchange of cations between minerals and solutions http://www4.uwsp.edu/geo/faculty/lemke/geomorphology/ Commonly exchanged cations: H +, K +, Na + Ca 2+, Mg 2+ Al 3+ Clay or organic compound Clay or organic compound http://elements.geoscienceworld.org/content/6/6/375/F2.expansion.html Clay mineral Exchangeable cations Clay Function #2: They Hold Nutrients!
- Slide 13
- Beware: Clay versus Clay or to a specific grain size (