Mass Movement 🎀 Flashcards
What is mass movement?
The movement of loose material, downhill on the earth’s surface due to gravity
What is regolith?
Loose material, such as soil gravel or rock that lies on the surface.
What is the gradient?
The angle of a slope
When is mass movement caused?
When something natural or man-made triggers it.
Name 6 causes of mass movement:
- Deforestation
- Heavy snow
- Heavy rain
- Earthquakes
- Building roads
- Overgrazing
What is overgrazing?
The repeated cultivation of land
What are the four things that affect mass movement?
- Gradient
- Vegetation
- Human activities
- Water content
Why does vegetation affect mass movement?
Vegetation significantly reduces the likelihood of mass movement by anchoring soil particles with its root systems, effectively holding the soil in place and preventing landslides, especially on slopes, by absorbing excess water and stabilizing the ground structure
What are human activities?
Risks such as undercutting, overgrazing, mining, deforestation,nand skiiing.
How is mass movement affected by water content?
Heavy rainfall makes regolith heavier and able to slide more easily, increasing the risk of mass movement.
What is an example of slow mass movement?
Soil creep
What is soil creep?
When solid moves very slowly, down slopes, only by about 1cm a year. It takes years to notice.
What are signs of solid creep?
Soil build up behind walls, tree trunks, poles, and fences bending in the same direction, accumulated soil in small ridges called terracettes.
What is an example of fast mass movement?
Bog bursts
What are bog bursts?
After heavy rain, when peat bog becomes full of water, the extra weight causes the bog to burst and slide downhill, often for many kilometres.
Where are big bursts common in Ireland?
On the wet, blanket bog covered hills of west Ireland.
Name a bog burst in Ireland.
The Drumkeeran in Co.Leitrim.
Are landslides a fast or slow movement?
They’re fast.
Why do landslides happen?
When huge amounts of regolith slide downhill, destroying everything in their path. This is because the slope became unstable.
Are mudflows fast or slow?
Fast
What is the slowest form of Mass Movement?
Soil creep
What is the fastest form of mass movement?
Mudflows
Describe mudflows
Mudflows are thick rivers of mud and rock that sweep downhill, burying everything in their way. When they move they’re thick like concrete, but when mudflows stop they become solid.
Why do mudflows happen?
When large amounts of water from rain, or melted ice, falls on the ground, and it doesn’t have time to be absorbed. The water, and everything else, then flows downhill.
