2.8 - Mass Movement

Question 1

What dip do bedding planes need to be for mass movement?

Answer 1

Seaward

Question 2

In rotational slumping, how does top-loading occur?

Answer 2

Cracks develop in dry weather
Rain runs through cracks and into sand underneath
Rain saturates layers on top

Question 3

What happens after top-loading in rotational slumping?

Answer 3

Rain moves along bedding plane creating internal pressure due to high pore-water pressure
Undercutting of cliff occurs
Rotation

Question 4

What type of slopes does rockfall occur on?

When does rockfall occur?

Answer 4

Steep slopes

When a wave-cut notch forms and part of the cliff isn’t supported anymore

Question 5

What are talus scree slopes?

Answer 5

Mounds of material with large boulders at the core and smaller material on top
Erosional processes erode the scree until it gets smaller

Question 6

Define rotational slumping

Answer 6

Sections of cliff remaining intact as they move down a curved slip plane, leaving behind a rotational scar above in the cliff face

Question 7

What is a flow?

Answer 7

When unconsolidated material move down a cliff face

Needs lots of water and a high clay content

Question 8

Rotational slumping needs what dip

Answer 8

Seaward (no sediment in front)