Mass movement Flashcards
Mass movement
The movement of loose material called regoliath (gravel/soil/stone) down a slope under the influence of gravity.
Factor 1, gradient
The steepness of a sloe, the steeper the slope the faster the movement
Factor 2, human activity
People dig into slopes and upland areas during construction (wind turbines/quarrying/mining) makes slope steeper and more unstable
Factor3, vegetation
Vegetation is grass and shrubs, they protect soil from weathering and erosion. It binds the soil together keeping it stable, helping prevent mass movement, if u remove the vegetation it encourages mass movement.
Factor4, water content
The water from rainfall makes the regoliath heavier, when it it heavier it travels downslope faster. It also acts as lubricant to make the movement easier and speeds up mass movement.
Name the 2 types of mass movement and an example
- Slow mass movement (soil creep)
- fast mass movement ( mudflow)
Describe a soil creep
A soil creep is the movement of soil down a slope under the influence of gravity. The tress begin to grow at an angle with the base of the tree down slope, the soil also moves downslope, steps called teracettes form, fences bend, poles tilt downwards, walls crack.
Describe a mudflow (long)
A mudflow is when soil and regoliath become saturated with water after heavy periods of rainfall and moves downslope like a river of mud. It is one of the fastest types of mass movement with speeds over 100 kmp. It can also occur after a volcano, in snowy regions the snow and ice melt rapidly and then the meltwater mixes with the ash from the ash from the aftermath of the volcanic eruption, the soil and rock then create a lahar, it is very dangerous. Ex: Nevado del kuiz in Columbia.
Give 3 ways that people control mass movement.
- people plant vegetation on slopes to stabilise them.
- steps can be built in a mountainside to trap the moving material
- restricted overgrazing keeps the vegetation cover and stops soil creep.
