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86 Cards in this Set

  • Front
  • Back
Rock breaks down
Physical removal at sources
Movement of eroded particles from sources by wind, water, ice
Effects of weathering
- New Minerals
- Surface oxidation
- Spheroidal weathering - rounds "corners"
-Differential weathering- favors resistant rocks
Disintegregation of rocks =
Physical weathering
Frost wedging
Type of Phsycial weathering where rock is pried apart along joints and water expands upon freezing
Abrasion during transportation
Type of Physical weathing by friction by streams, wind, waves, and glaciers where grinding reduces size but increases surface area
Pressure release
A mechanical weathering process in which rocks that formed under pressure expand on being exposed at the surface
Pressure release of deeply formed rock with expansion of the rock body at the surface
The formation of sheet joints
Exfoliation dome
A large rounded dome of rock resulting when concentric layers of rock are stripped down fromt the surface of a rock mass
Removal process of sheet joints
Other Examples of Mechanical Weathering
- Plant Growth
_ Burrowing animals
- Crystallization Pressures (salt crystals can weather our sidewalks)
- Extreme temperature changes- Fire
Mechanical Weathering increases...
surface area and increases potential for more weathering...physical and chemical
Surface Weathering is assisted by the roles of
-Oxygen or Hydrogen ions from acid
- The reaction of any substance with water
_ Hydrogen ions attack and replaces other positive ions
Chemical Weathering is similar to the effects of...
Role of Acid
Hydrogen ions in water
Solution weathering
- Calcite (in limestone) dissolves in acidic water
_ fluted (channeled) rock surface
- caves
Carbonic Acid H2CO3
CO2 + H2O -> H2CO3
H2CO3 -> H(+) + HCO3(-) in water
Chemical weathering of feldspar
H(+) + feldspar -> clay mineral
Weathering and climate
Hotter / wetter = FASTER!
Chemical weathering of other minerals
Weathering concentrates diamonds
Surface weathering is related to Bowen's Reaction Series
- The temperature of crystallization reflect rates of weathering
- First to crystallize = first to weather!
- High Fe content = more unstable at surface
reactions to surface temperatures and pressures
Rocks decompose to
form new substances and new minerals
The higher the iron content of igneous rocks =
the faster those minerals are to weather to more stable sedimentary minerals
iron oxide produced by weathering
tropical soil
hard layer of soil
A horizon
zone of leaching soil
Role of Oxygen in oxidation
Fe in ferromagnesian minerals becomes oxidized to form sedimentary rocks
Hematite 4Fe + 3O2 ->
2Fe2O3 iron oxide/red
Limonite wih water =
Fe2O3 = nH2 O: n=1,2, or 3 geothite/ yellow (HFeO2)
- Unconsoliated material above bedrock
- Weathered material and organic matter
~ Supports plant life
- Formed by weathering
different grain sizes of soil
fine grain wind blown deposit of silt and clay
The long term of precipitation and temperature of an area
Soil Horizon layer order
O, A, B, C
Soil Horizon O
Organice material just below ground vegetation
Soil Horizon A
Leaching by downward percolating H2O
Soil Horizon B
Accumulation of clay minerals (Fe oxides, and calcite)
Soil Horizon C
Fragments mechanically weathered from bed rock and some partially decomposed
Pedalfer is formed from
downward leaching
Pedocal is formed from
upward / evaporation
- Harpan: calcite or caliche
Buried soil =
paleosols: records of past soil
Factors of soil
Parent rock, slope, and time
Residual soil
on bedrock or regolith (formed in place)
Transported soil
loess or alluvium (wind and water borne)
Bauxite is a principal ore of...
Organic activity
Ao horizon organisms are important
Preventing landslide
- Preventing mass wasting of debris
_ Preventing rockfalls and rockslides on highways
excess construction on unstable slopes (...those homes in So. California)
cutting the loe of an unstable slope (highwy problems)
Unstable dams
the problem with the town of Kelly, Wyoming in 1925
Debris fall
- free falling mass of debris
- bedrock breaking loose on cliffs
- Talus - at the base of cliffs is the result of broken rocks
Debris Avalance
- very rapid, turbulent flow of debris
_ this same speed and flow category could pertain to a broken up Rock Avanlanche
- Primarily flow of debris
- May involve some water
- May involve rational sliding (slump)
- Scarp- left above fail mass
- Hummocky surface in lower part
- May be slow or fast
Classification of Mass Wasting

Type of Movement
- Flow = Turbulent
- Slide = Coherent (Translational slide and rotational slide (stump))
- Fall = Moving through the air
Classification of Mass Wasting

Nature of Movement
- Turbulent (internal/moving within itself)
- Coherent (bedrock)
- Through the air
Classification of Mass Wasting

Rate of Movement
- Extremely slow: 1mm/year
- Rapid: >100km/hour
Classification of Mass Wasting

- Bedrock
- Debris ("soil", sediment)
Mass Wasting
- Masses of debris or bedrock moving downhill
- Landslides and slower movements
- Driven by Gravity
Debris Flow
- Motion taking place throughout moving mass
- May be so like: creep or solifluction
- Or faster movements like Earthflow, Mudflow, Debris Avalance
Surficial Processess
- Erosion, transportation, decomposition on the Earth's surface
- Landscapes created and destroyed
- Involves atmosphere, water, gravity
Surficial Agents
Mass wasting, running water (streams) glaciers, wind, water, waves, ground water
Types of Flow

- gentle slopes
- NOT considered a form of landslide
- Vegetation slows movement
- Very slow flow (<1cm/year)
Creeps are facilitated by
water in soil or by freeze-thaw in colder climates
The movement of thawed surface soil or sediment over permafrost.

-occurs in cold climates only!
-usually slow but may accelerate
"permanently" frozen ground
- Flow of watery debris- more water than in Earthflow and faster
Mudflows occur when
Vegetation is sparse or lacking
(Dry climates like deserts, volcanoes with pyroclastic flows: Lahars, or after forest fires)
-Bedrock involved
- Sliding alone planes of weakness parallel to slope (Bedding planes, foliation planes, and fractures/joints in rock)
Debris slide
Debris moving along a well-defined surface
Controlling Factors

- Does add weight
- May lubricate some bedding planes to encourage slides
The increase in pore pressure in saturated debris...
decreases shear strength
Surface tension is unsaturated debris...
increases shear strength
Controlling Factors

Climatic controls
- Ice
- Water
- Precipitation
- Vegitation
Controlling Factors (Gravity)

Shear force
The force of gravity approaching slope angles
Controlling Factors (Gravity)

shear strength (the material strength or the "stick" component)
Controlling Factors of Mass Wasting
- Slope angle
- Local relief
- Thickness of debris over bedrock
- Planes of weakness (in bedrock)
~Bedding planes od sedimentary rocks, foliation, joints or faults
Alignment in Metamorphic Rocks
Joints or Faults
Structural breaks in the bedrock
Bedding planes, foliation, and joints and faults are all parallel to the slope which equals...
most dangerous!!!
Water in pore space is a...
critical factor!!