Module 1: Weathering and Soil Development Video Notes
Physical weathering:
Landslides very important process for generating chemically weathered materials.
Saltation
Rivers move particles and bang them together and are very important.
Comminution: particles hitting other particles into smaller ones
Comminution is important for chemical weathering
The more surface area, the more chemical weathering can ccur bc more room for chemical reactions.
Small particles have bigger surface area to volume ratio.
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Hydrolsis: acid with water to react to form clay mineral
Chemical weathering:
shale:
Illite most abundant
Quartz sandsotne
chert (opal)
evaporites
Chemical weathering occurs
Least stable minerals : olivine, pyrozene, amphibole biotite) weather easiest
Most stable: k-spar, muscovite, quartz, hard to weather
Chemical weathering products:
Stable primary mineral grains
Ions in solution, introduced into water by chemical degradation of primary mineral grains
In situ minerals:
by product of incongruent weathering
Limiting facotrs for chemical weather:
Water: more water, more chem reaction
Temper: warmer temp more chem reacion
Time: longer time more weathering
Places that are like that are:
warm, wet, and flat: example Amazon river basin
dry cold mountainous: least amount of chemical weathering occuring. Example, Antartica
Typeps of insitu minerals forming from chemical weathering:
oxides
amorphous or microcrystalline silica
Clay minerals:
Kaolinite
illite
chloritre
and expandable clays
Minca and clay minerals are phyllosillicates:
sheet or layered silicated with silica tetrahedra and octahedral layer
Kaolinite:
1:1 T-O Clay
Mica (illite)
2:1 T-O-T
When potassium is in interlayer, it is illite
When water is in interlayer, it is smectite or montmorillonite, which are swelling clays
Chloritee:
T-OT- veyr complex clay
Characterisitc in colder drier climates
O horizon: All organic material
A: mixture of organic and non organic
Module 2
Sediment Texture:
Gravel: 2mm or larger
Sand: 0.063-2mm
Mud: <0.063