Ch.9 Mass Movement Flashcards
(19 cards)
Mass movement
the movement of loose material on the earth’s surface due to gravity
Regolith
loose material, formed by weathering and erosion, made up of soil, gravel and rocks
Gradient
The angle of a slope
Lahars
form when volcanic eruptions which melt snow on volcanic cones, causing huge amounts of water to flow downhill suddenly
Name 4 types of mass movement
- Soil creep
- bog bursts
- mudflows
- landslides
soil creep
It occurs as soil moves very slowly down gentle slopes, only noticed by its effects on the surface
bog bursts
when a peat bog becomes completely full of water after heavy rain and causes it to burst and slide downhill
mudflows
Thick rivers of mud and rock that sweep downhill, burying everything in their path, after heavy rain
landslides
When huge amounts of regolith slide downhill at a great speed, destroying everything in their path
Soil creep features
- gentle
- dry
- slow
Bog bursts features
- Gentle to steep
- wet
- fast
Mudflows features
- Gentle to steep
- Wet
- Very rapid
Landslides features
- Steep
- Dry
- Rapid
Name 3 effects of mass movement
- death or injury
- polluted water
- migration
What factors influence mass movement
- gradient/slope
- vegetation
- water content
- Human activities
Gradient/slope
Steep slopes have more mass movement
Vegetation
Plant roots hold soil together preventing mass movement
Human activities
Increase risk of mass movement (undercutting slopes)
Water content
Heavy rainfall makes regolith heavier and able to slide more easily
