What would define a ground slope?
A ground slope is ground having an inclined surface.
What is mass movement or slope failure?
Mass movement is the movement of regolith and masses of rock downhill.
What is the difference between a talus and a talus slope?
A talus is rock and soil fragments that accumulate in a pile at the base of a ridge or cliff. A talus slope is an inclined surface of talus.
Draw and describe an angle of repose that is associated with loose sediments.
An angle of repose is the steepest angle at which loose grains will remain stable without sliding downslope.
What is cohesive force?
Cohesive force is the resistance of an object to move downhill.
Which factor is probably most important that strengthens cohesive forces?
Friction is probably the most important factor that strengthens cohesive force.
How much “relative amounts” of water is needed to increase cohesion?
Moist is the amount of water needed to increase cohesion.
How does removal of vegetation reduce cohesive forces?
Removing vegetation whose roots can no longer help bind sediments together reduces cohesion.
How does excess water content weaken cohesion? (how does water content play a role?)
Abundant water lubricates and adds weight to a mass.
Draw a picture and describe expansion/contraction or wetting/drying cycles.
freeze/wet = up/expand, thaw/dry = contract.
Compare a slope in equilibrium.
A gentle slope = equilibrium.
Why is slope gradient important in regards to mass movement?
The steeper the gradient, the faster that mass movement can take place.
Describe how one type of mass movement can change to another type of mass movement.
One type of mass movement can change over to another type of mass movement, such as creep movement becoming a debris flow.
Define mass movement creep, including freeze/thaw that we drew in class.
Creep is extremely slow, almost imperceptible downslope movement of soil and rock debris.
What physical objects on the Earth’s surface are associated with creep (how do you recognize that creep is occurring in the area)?
Cracks are associated with creep.
Discuss the effects of expansive clays in South Texas, especially on foundations during droughts and periods of heavy rainfall.
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Describe a typical “mixture” that can form a debris flow.
A debris flow can consist of mud, water and rock fragments (regolith).
What can be the common “lubricant” for debris flows?
Water can be a common lubricant for debris flows.
Describe the Blackhawk Slide?
The Blackhawk Slide was the largest debris flow in the US, reaching speeds of 270 mph.
How do we distinguish lahars from other type of debris flows?
Lahars are a volcanic debris flow composed mostly of volcanic ash and lava flows.
Along which tectonic zone are lahars most common?
Lahars are more common along tectonic convergent zones.
What is the relationship between Tacoma, WA and Mt. Rainier in regard to lahars?
Tacoma, WA is built on top of ancient lahars.
What happens to the consistency or hardness of the mud when a mudflow stops flowing?
The consistency of the mud rapidly becomes hard.
Describe a boulder field.
Boulder fields are long, relatively narrow masses of angular rock debris that moves very slowly.
