There are 3 main types of rocks:
1.Igneous rocks : Extrusive Intrusive
2.Sedimentary rocks: Clastic Chemical
3.Metamorphic rocks:heat pressure
Weathering:
Mechanical weathering :(coarse cohesionless) Gravels and Sands
1) Water 2)Glaciers 3)Wind 4)Thermal Expansion/ Contraction 5) Freeze/Thaw 6) Gravity/Landslide
Chemical weathering: (fine grained cohesice) Silts and Clays
Acids and salts react
Soil Formation
Residual Soilds- Soils that formed in place:
a) Particle size assorment tiwh depth
b) Properties like parent rock
c) Pretty uniform horizontally
Transported Soils- Moved from place of origin:
1) Alluvial soils-Streams, running water
2)Lacustrine soils- Depostion in Lakes
3)Glacial soils-Glaciers
4) Maring soils- Ocean depostion and formation
5) Aeolian soils-wind depositon (e.g.loess)
6)colluvial soils - Gravity, rockfall, landslide
Soil Partivle Size
Boulders Cobbles Gravel Sand 200 Sieve 0.075mm Silt Clay
Coarse-Grained Fine-Grained
(Bulky particles, gravity forces predominate) cohesionless (Flaky particles, surace forces predominate)cohesive
Clay Particles:3 most common, Kaolinite, Illite, and Mantmorillonite
Silica Tetrahedro Aluminum Octahedron
form molecular "sheets" that together consititure "clay"
Various combinations, various properties
Charge attracts both cations and water molecules, negatively
Why do we care about the double layer?
The thickness of the double layer relative to the clay particle size determines how the particle will interact with ohter particles and with water.
Thick: Dispersive soil
Settles in water slower; More dense
Lower Permeability; Less compressible
Weaker Stength
Thin: Flocculated soil
Settles in water faster, Open structure
Higher permability, More compressible
Higher Strenth
Shrink/Swell Potential can jack foundations and pavements
Erosive Potential can lead to piping in dams and levees
Geoenvironmental Applicaitons
Transportation/ Materials Applicaitons: LIme change, the soil from dispersive to flocculated
1.Igneous rocks : Extrusive Intrusive
2.Sedimentary rocks: Clastic Chemical
3.Metamorphic rocks:heat pressure
Weathering:
Mechanical weathering :(coarse cohesionless) Gravels and Sands
1) Water 2)Glaciers 3)Wind 4)Thermal Expansion/ Contraction 5) Freeze/Thaw 6) Gravity/Landslide
Chemical weathering: (fine grained cohesice) Silts and Clays
Acids and salts react
Soil Formation
Residual Soilds- Soils that formed in place:
a) Particle size assorment tiwh depth
b) Properties like parent rock
c) Pretty uniform horizontally
Transported Soils- Moved from place of origin:
1) Alluvial soils-Streams, running water
2)Lacustrine soils- Depostion in Lakes
3)Glacial soils-Glaciers
4) Maring soils- Ocean depostion and formation
5) Aeolian soils-wind depositon (e.g.loess)
6)colluvial soils - Gravity, rockfall, landslide
Soil Partivle Size
Boulders Cobbles Gravel Sand 200 Sieve 0.075mm Silt Clay
Coarse-Grained Fine-Grained
(Bulky particles, gravity forces predominate) cohesionless (Flaky particles, surace forces predominate)cohesive
Clay Particles:3 most common, Kaolinite, Illite, and Mantmorillonite
Silica Tetrahedro Aluminum Octahedron
form molecular "sheets" that together consititure "clay"
Various combinations, various properties
Charge attracts both cations and water molecules, negatively
Why do we care about the double layer?
The thickness of the double layer relative to the clay particle size determines how the particle will interact with ohter particles and with water.
Thick: Dispersive soil
Settles in water slower; More dense
Lower Permeability; Less compressible
Weaker Stength
Thin: Flocculated soil
Settles in water faster, Open structure
Higher permability, More compressible
Higher Strenth
Shrink/Swell Potential can jack foundations and pavements
Erosive Potential can lead to piping in dams and levees
Geoenvironmental Applicaitons
Transportation/ Materials Applicaitons: LIme change, the soil from dispersive to flocculated
