Exam 3 part 1 Flashcards
What causes mass wasting?
Gravity
When some one talks about mass wasting what are they usually referring to?
They refer to:
1) the downslope movement of rock
2) regolith and soil under direct influence of gravity
What are the 2 combined effects that produce stream valleys?
- Mass wasting
2. Running water
What is regolith?
Broken up rocks
What is the minimum angle required for mass wasting?
There is not minimum angle required
What kind of area can cause spectacular and rapid mass wasting?
Areas of rugged, geologically young mountains.
What slowly lowers the land surface and what keeps all land from being sea level?
Mass wasting lowers the land surface but plate tectonics/mountains building keep all land from being sea level
Ultimately where does mass wasting materials end up?
The ocean.
What can affect the gravity of a rock on a slope so that it falls downwards?
Shear stress
What is the opposite of shear stress?
Friction
Does gravity change at all?
No, gravity is a concept that does not change.
What makes a rock stable on a slope?
When the friction is greater than the shear stress
What are the two things that cause landslide to happen?
1) Controlling factors
2) Triggers
What are two controlling factors of landslides?
1) Water (Decreases friction/adds weight)
2) Oversteeping slopes
What are 3 things that could trigger a landslide?
1) Water (Rain/shear stress increase)
2) Earth Quakes (Cause extensive damage/liquidfaction
3) Removal of anchoring vegetation
What could cause a landslide (No triggers)?
Slope materials could weaken overtime and increase shear stress
What are the two things that classify a landslide event?
1) Types of material involved
2) Type of motion
What are the 3 types of materials involved with a landslide?
1) Mud (Clays and silts)
2) Earth (Regolith)
3) Rock
What are the 3 types of motion involved with an landslide?
1) fall (free falling pieces)
2) Slide (Material moves along a surface as a mass)
3) flow (Material moves as a chaotic mixture)
What is a talus slope?
Debris that piles up to a characteristic angle (Looks lose, like sand)
What are the 7 different forms of mass wasting?
1) Slump
2) Rock Slide
3) Debris Flow
4) Earth Flow
5) Creep
6) Solifluction
7) Submarine landslides
what is a slump?
Movement of mass of rock or loose material as a unit along a curved surface
What is a rock slide?
Blocks of bedrock slide down a slope. Generally fast and destructive.
Describe what a debris flow is?
It’s a lahar, mostly soil, regolith, water. Usually in channels in dry areas
What is an Earth flow?
This is a flow of soil that is clay or silt, it is saturated by water and is formed on hillsides in humid regions, usually next to highways
What is a creep?
Slow moving soil and regolith, caused by the expansion and contraction of material (Ice formation). Can be seen by bent tree stumps
What is solifluction?
This is a gentle slope of mass wasting, usually areas that were under permafrost thaw out and they slide downhill because they are ontop of impermeable clay
What are submarine landslides?
They are little landslides that occur on the flank of seamounts which are underwater volcanoes. When the slide occurs, water replaces it causing tsunamis.
What are two slow moving mass wasting?
1) Creep
2) Solification
What is the hydrolic cycle?
The hydrolic cycle is a summary of the circulation of earth’s water supply.
What are the six parts to the hydrolic cycle?
1) Precipitation
2) Evaporation
3) Infiltration
4) Run off
5) Transpiration
6) Evaportranspiration
What’s the first part to the hydrolic cycle?
Evaporation
What powers evaporation and where does it usually occur?
Solar energy and usually occurs from the ocean
Where do the salts in the ocean come from?
Chemical weathering from land
What kind of hazard are sinkholes?
A ground water hazard
What purifies water and makes it fresh?
Evaporation
Where do oceans get their chemistry from?
From land streams that take both solids and particles to the ocean
How are streams still moving even without rain?
ground water
What is a sheetflow?
This is running water without being confined to a canal
What are rills?
They are tiny channels of water that are caused by sheet flow
What are the 5 things that will control infiltration capacity?
1) Intensity and duration of rainfall
2) Prior wetted condition of the soil
3) Soil texture
4) Slope of the land
5) Nature of the vegetation cover
What is the perfect soil?
One that has both air and space, both porous and permeable
What is porosity and what is permeability?
Porosity is the amount of space you have and permeability how well those spaces are connected
In the terms of porosity and permeability, where does clay stand?
Clay is porous but not permeable
Why does water cling?
Because of electrical charges
Is the dormant season a better time for infiltration?
Yes.
If you see rills in the soil, what does that tell you about the soil?
It tells me that the soil has no vegetation and that it is not permeable.
What are the two different type of stream flows and what is the difference?
1) Laminar (Smooth, organized, almost solid looking)
2) Turbulent (Jagged, unorganized, looks like moving water)
What are the 3 things that determine the velocity (stream flow)?
1) Gradient or slope
2) Channel characteristics including slope size, roughness
3) Discharge
How does gradient effect velocity/stream flow?
The steepness of the gradient will determine how fast it goes because gravity is controlling it
