Weathering And Mass Wasting Flashcards
What are the two types of weathering?
Mechanical and chemical.
What does colluvial mean?
Deposited by gravity
What different types or forces of mechanical weathering exist?
Frost
Pressure release
Temperature
Biota
What occurs due to frost?
Mechanical weathering; frost expansion breaks rocks
Creates colluvial deposits called talus
What is talus?
Colluvial deposits; it’s angle of repose is 35-37 degrees
What is pressure release?
Removal of large material causes rock below to expand
Called exfoliation
How does temperature cause weathering
Heat from fires or extreme events can cause rock expansion
(IE Exploding or cracking rock in campfire)
How can biota be a cause of rock weathering?
Tree roots exploiting a crack in a rock for example, putting more pressure on it
What are the three types of chemical weathering
Solution/carbonation
Oxidation
Hydrolysis
How does solution/carbonation weathering occur?
Rain water is acidic and can react with the calcium carbonate in rocks like limestone and marble
Creates sinkholes and karst topography
What is oxidation in terms of chemical weathering?
The rusting of iron content in rocks causing their degradation
What are the two main factors in mass movement
Gravity first
Waters a close second
What fundamentally defines how mass movement occurs?
When the forces of gravity exceed the material/slopes resistance occurs
How does capillary action relate to mass wasting?
Particles of small sizes (clay/silt) can be held together with a small amount of moisture and form steep slopes
Too much water saturation can cause them to fail
What are types of slow mass movement are there?
Soil creep
Soliluction
Rock glaciers
What is soil creep?
Slow movement of soil on slopes >5 degrees
Causes terracettes
What is solifluction?
Top layer dethawing atop a frozen layer.
Occurs on very gentle slopes
Usually at high elevations or up north
What is a rock glacier?
A mix of rock and ice that is moving like a glacier but slower than a ice glacier
What are types of rapid mass movement?
Rotational slumps
Rockfall
Debris flows
Snow avalanches
What is a rotational slump?
Unstable blocks rotate as they slide, ends up stepped
Caused by undercuts and saturation
What is rockfall
Unstable blocks break loose, often due to water
Sometimes occurs on sloped bedding planes
Creates talus
What is debris flow?
Saturated layers of soil and rocks
Usually caused by water running on soils where it usually isn’t
Ie creek diverting course or water run off in fire altered landscapes
