Mass Wasting

Question 1

what is mass wasting

Answer 1

It is the downward movement of weathered material due to force of gravity

Question 2

What effect does water have on mass wasting

Answer 2

Small amounts of water restrict the soil as it creates cohesion.
Large amounts of water lubricate the soil and assist with movement. Heavy rain also adds volume and weight which makes it more prone to down wasting

Question 3

Give 4 factors that influence the degree and speed of mass wasting movemet

Answer 3

1. Gradient - Rapid movement is more likely on steep slopes (40° incline to the vertical)
2. Rock structure - Inclined strata with more- & less resistant rock are more prone to mass wasting. The soil on impermeable rock(material can’t pass through it easily) can become saturated and move downhill. Water in cracks can increase the chance of the material breaking and fall
3. Vegetation - soil with less vegetation is prone to movement as there aren’t many roots binding the soil. When rain falls, there is less interception from plants therefore runoff will occur.
4. People - 1. Deforestation… decrease in vegetation leads to mass movement.
5. Urbanisation can lead to people building buildings and houses on hillslopes, making the slope more unstable
6. Farming…Overgrazing on slopes decreases vegetation and incorrect contour ploughing results in mass movements.

Question 4

Name the types of mass movements

Answer 4

Soil creep, Solifluction, Earthflow, mudflow, rockfall, slumps, landslides.

Question 5

Which types of mass movements are fast and briefly explain each

Answer 5

1. Rockfalls - occur on steep slopes when rock pieces break from parent rock due to weathering and fall
2. Landslide/Slump - Large mass of land breaks loose and slides down. Occurs in fault zone when the land has bak tilt and slumps or along a bedding plane. earthquakes trigger these
3. Mudflow - Occur when a stream of mud, flows down a steep slope on channels. Wet conditions are needed for mudflow

Question 6

Name and briefly explain the slow mass movements

Answer 6

1. Soil creep - Occurs when soil expands in warm temperatures or when heavy rainfall (adds volume and weight) expands the soil. The soil contracts when it’s dry or cooling. The soil expands perpendicularly and will contact in a new place.
2. Soilfluction - occurs when topsoil
   is saturated and slides of frozen soil underneath.
3. Earthflow - Occur when clay area is saturated with water and move down gentle slopes

Question 7

How do mass movements impact people and the environment?

Answer 7

1. People - Death and injury
   - Damage to property, & agricultural land and
   - Loss of homes
   - Damage to infrastructure and transport
   routes
2. Environment - Destroy vegetation and forests
   - Change the nature of the slope
   - Remove the topsoil
   - Damage ecosystems and natural
   habitats

Question 8

Give some strategies to minimise the effects of mass movements.

Answer 8

1. Research the slope angle, geology, etc. before constructing on the slope.
2. Vegetation on a slope should be maintained when building
3. Wire mesh pr concrete can be put on the sides of mountains where cuttings were made. And stakes can be put in to make the slope more stable.
4. Drainage measure can be taken on slopes
5. Rules and regulations must exist/ applied when constructing on a mass movement prone slope
   5 Catch fence can be put on mountains prone to rockfalls.